Moving body

Abstract

To provide a moving body capable of improving aerodynamic drag-reduction effect in the moving body including the aerodynamic drag-reduction structure having a concave and convex structure.SOLUTION: A moving body is provided, the moving body 50 having an aerodynamic drag-reduction structure 1 on its surface, in which the aerodynamic drag-reduction structure 1 has a first region having a concave and convex structure and a second region adjacent to the first region, the first region and the second region extend in a band shape in a traveling direction of the moving body, a structure 20 is disposed on at least one of an upper surface or a side surface of the moving body 50, the aerodynamic drag-reduction structure 1 is disposed on the structure 20, and in the aerodynamic drag-reduction structure 1 disposed on the structure 20, height of a convex portion of the concave and convex structure of the first region and width of the first region and width of the second region in a direction intersecting the traveling direction of the moving body 50 are set based on boundary layer thickness at a position of the aerodynamic drag-reduction structure 1.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a moving body having a gas resistance reduction structure that reduces gas resistance. [Background technology]

[0002] In recent years, research into fluid resistance reduction technology has been actively conducted in order to achieve energy savings and reduced carbon dioxide emissions in the fields of moving objects that move through fluids and fluid transport, etc. Specifically, in the field of moving objects such as automobiles, railway vehicles, and aircraft, research into fluid resistance reduction technology has been actively conducted in order to achieve improved fuel efficiency and reduced carbon dioxide emissions.

[0003] Conventionally, known techniques for reducing fluid resistance include providing irregularities on the surface of an object (see, for example, Patent Documents 1 to 3). For example, riblets are known as a method for reducing frictional resistance, and dimples are known as a method for reducing pressure resistance. Patent Document 4 also discloses a technical concept of arranging rough and smooth surfaces to generate longitudinal vortices at the boundary between the rough and smooth surfaces, thereby suppressing flow separation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2010 / 29844 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-88880 [Patent Document 3] Japanese Patent Application Laid-Open No. 2001-50215 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-57390 [Patent Document 5] International Publication No. 2022 / 260181 Summary of the Invention [Problem to be solved by the invention]

[0005] The inventors of the present disclosure have devised a moving body equipped with an air resistance reduction structure having a concave-convex structure, which utilizes a technology for suppressing flow separation by generating vortices at the boundary between a rough surface and a smooth surface, as described in Patent Document 5. However, for practical use, further improvement in the air resistance reduction effect is desired.

[0006] The present disclosure has been made in consideration of the above-described situation, and aims to provide a moving body that is equipped with a gas resistance reduction structure having a concave-convex structure and that is capable of improving the gas resistance reduction effect. [Means for solving the problem]

[0007] One embodiment of the present disclosure provides a moving body having a gas drag reduction structure on its surface, wherein the gas drag reduction structure has a first region having a concave-convex structure and a second region adjacent to the first region, the first region and the second region extending in a band shape in the direction of travel of the moving body, a structure is disposed on at least one of the top surface or side surface of the moving body, the gas drag reduction structure is disposed on the structure, and in the gas drag reduction structure disposed on the structure, the height of the convex portions of the concave-convex structure of the first region, and the width of the first region and the width of the second region in a direction intersecting the direction of travel of the moving body are set based on the boundary layer thickness at the position of the gas drag reduction structure. [Effects of the Invention]

[0008] The present disclosure provides an advantage that it is possible to improve the gas resistance reduction effect in a moving body that is provided with an gas resistance reduction structure having a concave-convex structure. [Brief explanation of the drawings]

[0009] [Figure 1] 1A and 1B are schematic plan and cross-sectional views illustrating a gas drag reduction structure according to the present disclosure. [Figure 2] 1 is a schematic perspective view illustrating a gas drag reduction structure according to the present disclosure. FIG. [Figure 3] 3A to 3C are schematic diagrams illustrating gas flows in a gas drag reduction structure according to the present disclosure. [Figure 4] 1A to 1C are a schematic perspective view, a side view, and a top view illustrating a moving body according to the present disclosure. [Figure 5] 3A to 3C are schematic diagrams illustrating gas flows in a gas resistance reduction structure. [Figure 6] 1 is a schematic side view illustrating a moving body according to the present disclosure. [Figure 7] 1 is a schematic side view illustrating a moving body according to the present disclosure. [Figure 8] 1 is a schematic cross-sectional view illustrating a gas drag reduction structure according to the present disclosure. [Figure 9] 1 is a schematic perspective view illustrating a gas drag reduction structure according to the present disclosure. FIG. [Figure 10] 1A and 1B are schematic plan and cross-sectional views illustrating a gas drag reduction structure according to the present disclosure. [Figure 11] 1A and 1B are schematic plan and cross-sectional views illustrating a gas drag reduction structure according to the present disclosure. [Figure 12] 1 is a schematic plan view illustrating a gas drag reduction structure according to the present disclosure. [Figure 13] 3 is a schematic cross-sectional view illustrating an example of the concave-convex structure of a first region of the gas drag reduction structure according to the present disclosure. FIG. [Figure 14] 3 is a schematic cross-sectional view illustrating an example of a convex portion in the concave-convex structure of a first region of the gas drag reduction structure according to the present disclosure. FIG. [Figure 15] 1 is a schematic plan view illustrating a gas drag reduction structure according to the present disclosure. [Figure 16] 1 is a schematic cross-sectional view illustrating an example of a concave-convex resin film having a gas resistance reducing structure according to the present disclosure. [Figure 17] 1 is a schematic cross-sectional view illustrating an example of a concave-convex resin film having a gas resistance reducing structure according to the present disclosure. [Figure 18] 1 is a schematic side view illustrating a structure and a gas drag reduction structure according to the present disclosure. FIG. [Figure 19]1A to 1C are schematic top, side and rear views showing a truck-shaped model. [Figure 20] 1A and 1B are schematic top and side views showing a model of a truck shape. DETAILED DESCRIPTION OF THE INVENTION

[0010] Embodiments of the present disclosure will be described below with reference to the drawings and the like. However, the present disclosure can be implemented in many different forms and should not be construed as being limited to the description of the embodiments exemplified below. Furthermore, to clarify the explanation, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual form, but these are merely examples and do not limit the interpretation of the present disclosure. Furthermore, in this specification and each drawing, elements similar to those described above with reference to the previous drawings may be designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0011] In this specification, when describing an aspect in which another component is disposed on a certain component, the term "above" or "below" includes, unless otherwise specified, both a case in which another component is disposed directly above or below a certain component so as to be in contact with the component, and a case in which another component is disposed above or below a certain component with another component interposed therebetween. Also, in this specification, when describing an aspect in which another component is disposed on the surface of a certain component, the term "on the surface" includes, unless otherwise specified, both a case in which another component is disposed directly above or below a certain component so as to be in contact with the component, and a case in which another component is disposed above or below a certain component with another component interposed therebetween.

[0012] The mobile body in this disclosure will be described in detail below.

[0013] The moving body in the present disclosure is a moving body having a gas resistance reduction structure on its surface, the gas resistance reduction structure having a first region having a concave-convex structure and a second region adjacent to the first region, the first region and the second region extending in a band shape in the direction of travel of the moving body, a structure being arranged on at least one of the top surface or side surface of the moving body, the gas resistance reduction structure being arranged on the structure, and in the gas resistance reduction structure arranged on the structure, the height of the convex portions of the concave-convex structure of the first region, and the width of the first region and the width of the second region in a direction intersecting the direction of travel of the moving body are set based on the boundary layer thickness at the position of the gas resistance reduction structure.

[0014] The present disclosure utilizes a technology that generates vortices at the boundary between a rough surface and a smooth surface to suppress flow separation. When gas flows along a rough surface and a smooth surface, the frictional resistance of the rough surface is greater than the frictional resistance of the smooth surface. Therefore, the gas flow velocity is faster on the smooth surface and slower on the rough surface, resulting in a difference in gas flow velocity between the smooth surface and the rough surface. As a result, vortices are generated at the boundary between the rough surface and the smooth surface. In the present disclosure, the first region has an uneven structure and is a region where the frictional resistance of the gas is high. On the other hand, the second region is a region where the frictional resistance of the gas is low. Therefore, when gas flows along the surface of the gas drag reduction structure, vortices are generated at the boundary between the first region and the second region.

[0015] As described above, the second region is a region in which the frictional resistance of the gas is smaller than that of the first region. The second region does not have a concave-convex structure and has a flat surface. Alternatively, the second region may have a concave-convex structure, in which case the height of the convex portions in the second region is smaller than the height of the convex portions in the first region.

[0016] 1(a) to 1(c) and 2 are schematic plan views, cross-sectional views, and perspective views showing an example of a gas drag reduction structure according to the present disclosure. FIG. 1(b) is a cross-sectional view taken along line AA in FIG. 1(a), FIG. 1(c) is a cross-sectional view taken along line BB in FIG. 1(a), and FIG. 2 is a perspective view of FIG. 1(a). As shown in FIGS. 1(a) to 1(c) and 2, in the gas drag reduction structure 1, a first region 2 having an uneven structure 10 including a plurality of protrusions 11 and recesses 12 and a second region 3 adjacent to the first region 2 extend in a strip-like shape in the traveling direction D1 of the moving object. In the example shown in FIGS. 1(a) to 1(c) and 2, the first regions 2 and the second regions 3 are alternately arranged in a direction D2 intersecting the traveling direction D1 of the moving object.

[0017] 3(a) and 3(b) are schematic diagrams illustrating the flow of gas in the gas resistance reduction structure of the present disclosure, and Fig. 3(b) is a cross-sectional view taken along line AA in Fig. 3(a). As shown in Fig. 3(a), when gas F flows along the surface of the gas resistance reduction structure 1, the flow direction d of the gas F between the first region 2 and the second region 3 is F A vortex V is generated near the boundary parallel to the first region. The generation of the vortex V can suppress the flow of gas F from separating from the surface of the gas drag reduction structure 1. When an object is placed in a gas flow, drag forces acting on the object include, for example, frictional resistance and pressure resistance. Frictional resistance is generated by friction between the gas and the surface. Pressure resistance is generated by the pressure difference between the front and rear. In other words, pressure resistance is generated by flow separation. In the gas drag reduction structure of the present disclosure, attention is focused on reducing pressure resistance, among other gas resistances. In the gas drag reduction structure of the present disclosure, flow separation can be suppressed by generating a vortex near the boundary between the first region and the second region, and gas resistance, particularly pressure resistance, can be reduced.

[0018] The inventors of the present disclosure have conducted extensive research into the gas resistance reduction effect of a moving body having a gas resistance reduction structure on its surface, and have found that arranging a gas resistance reduction structure at the front of the moving body relative to the moving direction of the moving body improves the gas resistance reduction effect. This is for the following reasons. First, the gas resistance reduction structure suppresses flow separation at the front of the moving body, thereby suppressing a decrease in gas flow velocity from the front to the rear of the moving body. As a result, more gas flows rearward of the moving body, increasing back pressure. This reduces the pressure difference between the front and rear of the moving body, lowering pressure resistance. Therefore, the gas resistance reduction effect is improved.

[0019] In moving bodies such as automobiles, railway vehicles, and aircraft, structures such as exterior parts are sometimes arranged on the outside of the moving body. As a result of further investigation, the inventors of the present disclosure found that flow separation may occur at the structure, that a gas resistance reduction effect can be obtained by arranging a gas resistance reduction structure on the structure, and that if the structure is an aerodynamic part, the gas resistance reduction effect can be enhanced by arranging a gas resistance reduction structure on the structure.

[0020] In a flow around an object, a very thin layer on the object's surface is strongly affected by viscosity. This layer that is strongly affected by viscosity is called a boundary layer. The inventors of the present disclosure conducted further studies to improve the gas drag reduction effect, focusing on the boundary layer thickness. The boundary layer thickness increases as the distance from the tip of the object increases. The inventors of the present disclosure then discovered that the gas drag reduction effect can be improved by designing the height of the convex portions of the concave-convex structure of the first region, the width of the first region, and the width of the second region of a gas drag reduction structure disposed on a structure based on the boundary layer thickness at the position of the gas drag reduction structure. The present disclosure is based on such findings.

[0021] 4(a) to 4(c) are schematic perspective views, side views, and top views showing an example of a mobile body according to the present disclosure, in which the mobile body is a bus. As shown in FIGS. 4(a) to 4(c), the mobile body, bus 50, is provided with an air conditioning unit 52 and a rear spoiler 53 on top of a vehicle body 51. The air conditioning unit 52 and rear spoiler 53 are structure 20 disposed on the upper surface of the bus 50 (mobile body). Gas drag reduction structures 1a and 1b are disposed in front of the air conditioning unit 52 (structure 20) and on the upper surface of the rear spoiler 53 (structure 20).

[0022] As described above, the boundary layer thickness increases with increasing distance from the tip of an object. In the gas drag reduction structure 1a disposed in the air conditioning unit 52 (structure 20), the height H1 of the convex portions 11 of the concave-convex structure 10 in the first region 2, and the width W1 of the first region 2 and the width W2 of the second region 3 in the direction D2 intersecting the traveling direction D1 of the bus 50 (mobile body) are set based on the boundary layer thickness at the position of the gas drag reduction structure 1a. In addition, in the gas drag reduction structure 1b disposed in the rear spoiler 53 (structure 20), the height H1 of the convex portions 11 of the concave-convex structure 10 in the first region 2, and the width W1 of the first region 2 and the width W2 of the second region 3 in the direction D2 intersecting the traveling direction D1 of the bus 50 (mobile body) are set based on the boundary layer thickness at the position of the gas drag reduction structure 1b.

[0023] 4(a) to 4(c), in addition to the air conditioning unit 52 (structure 20) and the rear spoiler 53 (structure 20), gas drag reduction structures 1c are also arranged at corners that form the boundaries between the front and side of the bus 50 (mobile body) and at corners that form the boundaries between the back and side of the bus 50 (mobile body). Specifically, the gas drag reduction structures 1c are arranged on the front and rear sides of the bus 50.

[0024] In the present disclosure, by disposing a gas drag reduction structure on a structure, flow separation at the structure can be suppressed. Therefore, a decrease in gas flow velocity from the structure to the rear of the moving body is suppressed. As a result, more gas flows into the rear of the moving body, increasing back pressure and reducing pressure drag.

[0025] Furthermore, in the present disclosure, in a gas drag reduction structure disposed in a structure, the height of the convex portions of the concave-convex structure in the first region is set based on the boundary layer thickness at the position of the gas drag reduction structure, thereby making it easier for vortices to be generated near the boundary between the first region and the second region. This further suppresses flow separation in the structure, thereby reducing pressure resistance. Furthermore, it is possible to suppress an increase in frictional resistance due to the concave-convex structure in the first region. That is, it is possible to reduce pressure resistance while suppressing an increase in frictional resistance due to the concave-convex structure in the first region. In other words, the benefit of reducing pressure resistance can be greater than the increase in frictional resistance due to the concave-convex structure in the first region.

[0026] 5(a) to 5(c) are schematic diagrams illustrating the relationship between the widths of the first and second regions in a direction intersecting the direction of travel of the moving body and vortices generated near the boundary between the first and second regions in a gas drag reduction structure. In FIGS. 5(a) to 5(c), δ represents the boundary layer thickness. For example, as shown in FIG. 5(a), when the width W1 of the first region 2 and the width W2 of the second region 3 in the direction intersecting the direction of travel of the moving body are large, a large vortex V is generated near the boundary between the first and second regions 2 and 3, but the vortex V does not easily reach the center of the first region 2 and the center of the second region 3. Furthermore, as shown in FIG. 5(c), when the width W1 of the first region 2 and the width W2 of the second region 3 in the direction intersecting the direction of travel of the moving body are small, the vortex V generated near the boundary between the first and second regions 2 and 3 is small, and the vortex V does not easily reach the outer edge of the boundary layer. In these cases, flow separation can be suppressed, but the effect is small.

[0027] In contrast, in a gas drag reduction structure placed on a structure, the width W1 of the first region 2 and the width W2 of the second region 3 in a direction intersecting the direction of travel of the moving body are set based on the boundary layer thickness at the position of the gas drag reduction structure, so that, as shown in Figure 5(b), for example, a large vortex V is generated near the boundary between the first region 2 and the second region 3, and the vortex V can be generated throughout the entire boundary layer.

[0028] Therefore, in the present disclosure, a gas resistance reduction structure is arranged on a structure, and in the gas resistance reduction structure arranged on the structure, the height of the convex portions of the uneven structure in the first region, and the width of the first region and the width of the second region in a direction intersecting the direction of travel of the moving body are set based on the boundary layer thickness at the position of the gas resistance reduction structure, thereby improving the gas resistance reduction effect.

[0029] FIG. 6(a) is a schematic side view showing an example of a mobile body according to the present disclosure, where the mobile body is a truck. In FIG. 6(a), the mobile body, truck 60, includes a cabin 61, a bed 62, and a roof spoiler 63. The roof spoiler 63 is a structure 20 disposed on the upper surface of the truck 60 (mobile body). A gas drag reduction structure 1a is disposed on the upper surface of the roof spoiler 63 (structure 20). In the gas drag reduction structure 1a disposed on the roof spoiler 63 (structure 20), the height H1 of the convex portion 11 of the concave-convex structure 10 in the first region 2, and the width W1 of the first region 2 and the width W2 of the second region 3 in a direction D2 intersecting the traveling direction D1 of the truck 60 (mobile body) are set based on the boundary layer thickness at the position of the gas drag reduction structure 1a. 6(a), in addition to the roof spoiler 63 (structure 20), gas resistance reduction structures 1c are also arranged at corners that are boundaries between the rear and side of a truck 60 (mobile body). Specifically, gas resistance reduction structures 1c are arranged on the rear side of a cabin 61 and the rear side of a loading platform 62.

[0030] FIG. 6(b) is a schematic side view showing an example of a mobile body according to the present disclosure, where the mobile body is a truck. In FIG. 6(b), the mobile body, truck 60, includes a cabin 61 and a bed 62, with an air deflector 64 on top of the cabin 61. The bed 62 and air deflector 64 form a structure 20 disposed on the upper surface of the truck 60 (mobile body). A gas drag reduction structure 1a is disposed in the front of the bed 62 (structure 20). In the gas drag reduction structure 1a disposed on the bed 62 (structure 20), the height H1 of the convex portions 11 of the concave-convex structure 10 in the first region 2, and the width W1 of the first region 2 and the width W2 of the second region 3 in a direction D2 intersecting the traveling direction D1 of the truck 60 (mobile body) are set based on the boundary layer thickness at the position of the gas drag reduction structure 1a. 6(b), the gas resistance reduction structure 1c is arranged not only on the loading platform 62 (structure 20) but also on the corners that form the boundaries between the rear and side surfaces of the truck 60 (mobile body). Specifically, the gas resistance reduction structure 1c is arranged on the rear side of the loading platform 62.

[0031] FIG. 6(c) is a schematic side view showing an example of a mobile body according to the present disclosure, where the mobile body is a truck. In FIG. 6(c), the mobile body, truck 60, includes a cabin 61 and a loading platform 62, and an air deflector 64 is provided above the cabin 61. The air deflector 64 is a structure 20 disposed on the upper surface of the truck 60 (mobile body). A gas drag reduction structure 1a is disposed in front of the air deflector 64 (structure 20). In the gas drag reduction structure 1a disposed on the air deflector 64 (structure 20), the height H1 of the convex portions 11 of the concave-convex structure 10 in the first region 2, and the width W1 of the first region 2 and the width W2 of the second region 3 in a direction D2 intersecting the traveling direction D1 of the truck 60 (mobile body) are set based on the boundary layer thickness at the position of the gas drag reduction structure 1a. 6(c), in addition to the air deflector 64 (structure 20), the gas resistance reduction structure 1c is also arranged at the corners that form the boundaries between the rear and side surfaces of the truck 60 (mobile body). Specifically, the gas resistance reduction structure 1c is arranged on the rear side of the loading platform 62.

[0032] FIG. 7(a) is a schematic side view showing an example of a moving body according to the present disclosure, where the moving body is a passenger car. In FIG. 7(a), a passenger car 70, which is the moving body, is provided with a roof spoiler 72 on top of a vehicle body 71. The roof spoiler 72 is a structure 20 disposed on the upper surface of the passenger car 70 (moving body). A gas drag reduction structure 1a is disposed on the upper surface of the roof spoiler 72 (structure 20). In the gas drag reduction structure 1a disposed on the roof spoiler 72 (structure 20), the height H1 of the convex portion 11 of the concave-convex structure 10 in the first region 2, and the width W1 of the first region 2 and the width W2 of the second region 3 in a direction D2 intersecting the traveling direction D1 of the truck 60 (moving body) are set based on the boundary layer thickness at the position of the gas drag reduction structure 1a. 7(a), in addition to the roof spoiler 72 (structure 20), the gas drag reduction structure 1c is also arranged at the corners that are the boundaries between the rear and side of a passenger car 70 (mobile body). Specifically, the gas drag reduction structure 1c is arranged on the rear side of the vehicle body 71.

[0033] FIG. 7(b) is a schematic side view showing an example of a moving body according to the present disclosure, where the moving body is a passenger car. In FIG. 7(b), the moving body, a passenger car 70, is provided with a rear spoiler 73 at the rear of a vehicle body 71. The rear spoiler 73 is a structure 20 disposed on the upper surface of the passenger car 70 (moving body). An air resistance reduction structure 1a is disposed on the upper surface of the rear spoiler 73 (structure 20). In the air resistance reduction structure 1a disposed on the rear spoiler 73 (structure 20), the height H1 of the convex portions 11 of the concave-convex structure 10 in the first region 2, and the width W1 of the first region 2 and the width W2 of the second region 3 in a direction D2 intersecting the traveling direction D1 of the truck 60 (moving body) are set based on the boundary layer thickness at the position of the air resistance reduction structure 1a. 7(b), in addition to the rear spoiler 73 (structure 20), the gas resistance reduction structure 1c is also arranged at the corners that form the boundaries between the rear and side of the passenger car 70 (mobile body). Specifically, the gas resistance reduction structure 1c is arranged on the rear side of the vehicle body 71.

[0034] In the examples shown in FIGS. 6(a) to 6(c) and FIGS. 7(a) to 7(b), the gas resistance reduction effect can be improved, similar to the example shown in FIG.

[0035] The mobile body in this disclosure will be described in detail below.

[0036] 1. Gas Drag Reduction Structure The gas drag reduction structure according to the present disclosure has a first region having a concave-convex structure and a second region adjacent to the first region, and the first region and the second region extend in a band shape in the traveling direction of the moving body.

[0037] (1) First area In the present disclosure, the first region has a concave-convex structure.

[0038] (a) Height of the convex part In the present disclosure, in a gas drag reduction structure disposed in a structure, the height of the convex portions of the concave-convex structure is set based on the boundary layer thickness at the position of the gas drag reduction structure.

[0039] Specifically, in a gas drag reduction structure disposed in a structure, the height of the convex portions of the concave-convex structure is preferably 0.01% or more and 50% or less, more preferably 0.1% or more and 30% or less, and even more preferably 0.5% or more and 15% or less, when the boundary layer thickness at the position of the gas drag reduction structure is taken as 100%.

[0040] In a gas drag reduction structure disposed on a structure, the boundary layer thickness at the position of the gas drag reduction structure is determined appropriately according to the height of the structure.

[0041] When the height of the structure is equal to or less than the boundary layer thickness δ0 at the position of the structure, the boundary layer thickness δ1 at the position of the gas drag reduction structure is calculated by the following formula (1). δ1=0.37(U0x1 / v) -1 / 5 x1(1) In the above formula (1), v represents the dynamic viscosity coefficient of the gas, U0 represents the flow velocity of the gas, and x1 represents the distance from the reference point at the tip of the moving body to the tip of the gas drag reduction structure.

[0042] On the other hand, when the height of the structure is greater than the boundary layer thickness δ0 at the position of the structure, the boundary layer thickness δ2 at the position of the gas drag reduction structure is calculated by the following formula (2). δ2=0.37(U0x2 / v) -1 / 5 x2(2) In the above formula (2), v represents the dynamic viscosity coefficient of the gas, U0 represents the flow velocity of the gas, and x2 represents the distance from the reference point at the tip of the structure to the tip of the gas drag reduction structure.

[0043] The "height of a structure" refers to the amount by which the structure protrudes. Specifically, when a structure is placed on the top surface of a mobile body, the "height of a structure" refers to the amount by which the structure protrudes vertically. Furthermore, when a structure is placed on the side of a mobile body, the "height of a structure" refers to the amount by which the structure protrudes horizontally. More specifically, when a structure is placed on the top surface of a mobile body, the "height of a structure" refers to the maximum vertical height of the structure from a horizontal plane including the foremost part of the contact point between the structure and the mobile body, based on the direction of travel of the mobile body. Furthermore, when a structure is placed on the side of a mobile body, the "height of a structure" refers to the maximum horizontal width of the structure from a vertical plane including the foremost part of the contact point between the structure and the mobile body, based on the direction of travel of the mobile body. Typically, structures are attached to the mobile body, so the boundary between the structure and the mobile body is clear. If the boundary between the structure and the main body of the moving object is unclear, the part where the shape begins to change is taken as the boundary between the structure and the main body of the moving object.

[0044] However, if a part of the mobile body or another structure is adjacent to the front of the structure, the maximum vertical height or maximum horizontal width of the structure may not necessarily be the protrusion amount of the structure. In such cases, the protrusion amount of the structure from the part adjacent to the front of the structure is considered to be the "height of the structure."

[0045] In the bus 50 (mobile body) shown in Figures 4(a) to 4(c), the air conditioning unit 52 (structure 20) and rear spoiler 53 (structure 20) are disposed on the upper surface of the bus 50 (mobile body). The height of the air conditioning unit 52 (height H11 of the structure 20) is the amount of protrusion of the air conditioning unit 52 (structure 20) in the vertical direction, that is, the maximum height of the air conditioning unit 52 (structure 20) in the vertical direction from a horizontal plane including the forefront portion (reference point E1 at the tip of the air conditioning unit 52 (structure 20) in Figure 4(b)) of the portion where the air conditioning unit 52 (structure 20) and the vehicle body 51 (mobile body main body) meet. In addition, the height of the rear spoiler 53 (height H12 of the structure 20) is the amount of protrusion of the rear spoiler 53 (structure 20) in the vertical direction, that is, the maximum height of the rear spoiler 53 (structure 20) in the vertical direction from a horizontal plane including the foremost part of the contact point between the rear spoiler 53 (structure 20) and the vehicle body 51 (main body of the moving body) (in Figure 4(b), this is the reference point E2 at the tip of the rear spoiler 53 (structure 20)).

[0046] In the truck 60 (mobile body) shown in Figure 6(a), a roof spoiler 63 (structure 20) is disposed on the upper surface of the truck 60 (mobile body). The height of the roof spoiler 63 is the amount of protrusion of the roof spoiler 63 (structure 20) in the vertical direction, that is, the maximum height of the roof spoiler 63 (structure 20) in the vertical direction from a horizontal plane including the foremost part (reference point E1 at the tip of the roof spoiler 63 (structure 20) in Figure 6(a)) of the part where the roof spoiler 63 (structure 20) and the cabin 61 (mobile body main body) meet, and is 0.

[0047] In the truck 60 (mobile body) shown in FIG. 6(b), a loading platform 62 (structure 20) is disposed on the upper surface of the truck 60 (mobile body). The height of the loading platform 62 (height H11 of the structure 20) is the amount of protrusion of the loading platform 62 (structure 20) in the vertical direction. In this case, a cabin 61 (part of the main body of the mobile body) and an air deflector 64 (another structure) are adjacent to the front of the loading platform 62 (structure 20). Therefore, the height of the loading platform 62 (height H11 of the structure 20) is the height at which the loading platform 62 (structure 20) protrudes from the part of the loading platform 62 (structure 20) adjacent to the front (the air deflector 64 in FIG. 6(b)).

[0048] In the truck 60 (mobile body) shown in Figure 6(c), the air deflector 64 (structure 20) is disposed on the upper surface of the truck 60 (mobile body). The height of the air deflector 64 (height H11 of the structure 20) is the amount of protrusion of the air deflector 64 (structure 20) in the vertical direction, that is, the maximum height of the air deflector 64 (structure 20) in the vertical direction from a horizontal plane including the foremost part (reference point E1 at the tip of the air deflector 64 (structure 20) in Figure 6(c)) of the part where the air deflector 64 (structure 20) and the cabin 61 (mobile body main body) come into contact.

[0049] In a passenger car 70 (mobile body) shown in Figure 7(a), a roof spoiler 72 (structure 20) is disposed on the upper surface of the passenger car 70 (mobile body). The height of the roof spoiler 72 (structure 20) is the amount of protrusion of the roof spoiler 72 (structure 20) in the vertical direction, that is, the maximum height of the roof spoiler 72 (structure 20) in the vertical direction from a horizontal plane including the forefront portion (reference point E1 at the tip of the roof spoiler 72 (structure 20) in Figure 7(a)) of the portion where the roof spoiler 72 (structure 20) and the vehicle body 71 (mobile body main body) meet, and is 0.

[0050] In a passenger car 70 (mobile body) shown in Figure 7(b), a rear spoiler 73 (structure 20) is disposed on the upper surface of the passenger car 70 (mobile body). The height of the rear spoiler 73 (structure 20) is the amount of protrusion of the rear spoiler 73 (structure 20) in the vertical direction, that is, the maximum height of the rear spoiler 73 (structure 20) in the vertical direction from a horizontal plane including the foremost part (reference point E1 at the tip of the rear spoiler 73 (structure 20) in Figure 7(b)) of the part where the rear spoiler 73 (structure 20) and the vehicle body 71 (mobile body main body) come into contact, and is 0.

[0051] The boundary layer thickness δ0 at the position of the structure is calculated by the following equation (3). δ0=0.37(U0x0 / v) -1 / 5 x0(3) In the above formula (3), v represents the dynamic viscosity coefficient of the gas, U0 represents the flow velocity of the gas, and x0 represents the distance from the reference point at the tip of the moving body to the reference point at the tip of the structure.

[0052] When the gas is air, in the above formulas (1) to (3), the dynamic viscosity coefficient v of air at 20°C is 1.512 × 10 -5 m 2 / s.

[0053] In the above formulas (1) to (3), the gas flow velocity U0 differs depending on the moving body. If there is a legal speed limit (legal maximum speed), the gas flow velocity is determined based on the legal speed. If there is no legal speed limit, the gas flow velocity is determined based on the maximum speed during normal movement.

[0054] When the moving body is a car, the gas flow velocity is determined based on the legal speed (maximum legal speed). The legal speed on ordinary roads is 60 km / h, and on expressways it is 100 km / h. Therefore, the gas flow velocity is set to 100 km / h. For automobiles such as large freight vehicles, the legal speed on expressways is 80 km / h, but when the moving body is a car, the gas flow velocity is set to 100 km / h.

[0055] When the moving object is a railway vehicle, the gas flow velocity is determined based on the maximum speed during normal operation. For railway vehicles, the maximum speed during normal operation is called the maximum operating speed or maximum line speed (maximum route speed). Maximum operating speed and maximum line speed vary depending on the vehicle and route. For the Shinkansen, the maximum operating speed is approximately 250 km / h to 320 km / h, so the gas flow velocity is set to 320 km / h. For linear motor cars, the maximum operating speed is planned to be 500 km / h, so the gas flow velocity is set to 500 km / h. For trains and locomotives other than the Shinkansen, the maximum operating speed is approximately 70 km / h to 110 km / h, so the gas flow velocity is set to 110 km / h.

[0056] When the moving object is an aircraft, the gas flow velocity is determined based on the maximum speed during normal flight. The economical and efficient speed at which an aircraft can travel as long a distance or for as long a time as possible with as little fuel consumption as possible is called the cruising speed. The cruising speed of a passenger plane is approximately 670 km / h to 900 km / h, so when the moving object is a passenger plane, the gas flow velocity is set to 900 km / h. The cruising speed of a helicopter is approximately 140 km / h to 240 km / h, so when the moving object is a helicopter, the gas flow velocity is set to 240 km / h. The cruising speed of air mobility is approximately 100 km / h to 160 km / h, so when the moving object is air mobility, the gas flow velocity is set to 160 km / h.

[0057] If the moving body is a ship, the gas flow velocity is determined based on the maximum speed during normal navigation. The cruising speed of a ship is approximately 30km / h to 45km / h, depending on the type of ship, so if the moving body is a ship, the gas flow velocity is set at 45km / h.

[0058] In the above equation (3), the distance x0 from the reference point at the tip of the moving body to the reference point at the tip of the structure refers to the distance along the surface of the moving body from the reference point at the tip of the moving body to the reference point at the tip of the structure in the direction of travel of the moving body.

[0059] The "reference point of the tip of the moving body" is the foremost part of the moving body that is located foremost relative to the moving direction of the moving body. If the foremost part of the moving body is a surface, the reference point is the center of that surface. If the moving body has multiple foremost parts, the foremost part that is located closest to the gas drag reduction structure is used as the reference point.

[0060] In this specification, the "mobile body" in the "reference point of the tip of the mobile body" refers to the main body of the mobile body. The "main body of the mobile body" refers to the parts that make up the outer shape of the mobile body, and includes the body and exterior parts of the mobile body. However, in this case, the protrusions of the following parts will not be taken into consideration: wipers, mirrors such as side mirrors and under-mirrors, and propeller blades.

[0061] Furthermore, the protrusion of the above-listed parts is not taken into consideration when calculating "the distance x0 from the reference point at the tip of the moving body to the reference point at the tip of the structure." Similarly, the protrusion of the above-listed parts is not taken into consideration when calculating "the distance x1 from the reference point at the tip of the moving body to the tip of the gas drag reduction structure." Similarly, the protrusion of the above-listed parts is not taken into consideration when calculating "the distance x2 from the reference point at the tip of the structure to the tip of the gas drag reduction structure."

[0062] The "reference point of the tip of the structure" is the foremost part of the structure that is located foremost relative to the direction of travel of the mobile body. If the foremost part of the structure is a surface, the reference point is the center of that surface. If the structure has multiple foremost parts, the foremost part of the multiple foremost parts that is located closest to the gas drag reduction structure is the reference point. If the structure is attached to the mobile body, the boundary between the structure and other parts is clear, and therefore the foremost part of the structure is also clear. On the other hand, if the structure is integrated with other parts and the boundary between the structure and other parts is unclear, the reference point of the tip of the structure is the part of the structure that is located foremost relative to the direction of travel of the mobile body and where the shape begins to change.

[0063] In FIG. 4(b), for the air conditioning device 52 (structure 20), the distance x0 is the distance x along the surface of the bus 50 (mobile body) from the reference point E0 at the tip of the bus 50 (mobile body) to the reference point E1 at the tip of the air conditioning device 52 (structure 20) in the traveling direction D1 of the bus 50 (mobile body). 0a Furthermore, for the rear spoiler 53 (structure 20), the distance x0 is the distance x along the surface of the bus 50 (mobile body) from the reference point E0 at the tip of the bus 50 (mobile body) to the reference point E2 at the tip of the rear spoiler 53 (structure 20) in the traveling direction D1 of the bus 50 (mobile body). 0b It is shown as follows.

[0064] In FIG. 6(a), for the roof spoiler 63 (structure 20), the distance x0 is the distance x along the surface of the truck 60 (moving body) from the reference point E0 at the tip of the truck 60 (moving body) to the reference point E1 at the tip of the roof spoiler 63 (structure 20) in the traveling direction D1 of the truck 60 (moving body). 0a In FIG. 6(b), for the loading platform 62 (structure 20), the distance x0 is the distance x along the surface of the truck 60 (mobile body) from the reference point E0 at the tip of the truck 60 (mobile body) to the reference point E1 at the tip of the loading platform 62 (structure 20) in the traveling direction D1 of the truck 60 (mobile body). 0a In FIG. 6(c), for the air deflector 64 (structure 20), the distance x0 is the distance x along the surface of the truck 60 (moving body) from the reference point E0 at the tip of the truck 60 (moving body) to the reference point E1 at the tip of the air deflector 64 (structure 20) in the traveling direction D1 of the truck 60 (moving body). 0a It is shown as follows.

[0065] In FIG. 7(a), for the roof spoiler 72 (structure 20), the distance x0 is the distance x along the surface of the passenger car 70 (mobile body) from the reference point E0 at the tip of the passenger car 70 (mobile body) to the reference point E1 at the tip of the roof spoiler 72 (structure 20) in the traveling direction D1 of the passenger car 70 (mobile body). 0aIn Fig. 7(b), for the rear spoiler 73 (structure 20), the distance x0 is the distance x along the surface of the passenger car 70 (mobile body) from the reference point E0 at the tip of the passenger car 70 (mobile body) to the reference point E1 at the tip of the rear spoiler 73 (structure 20) in the traveling direction D1 of the passenger car 70 (mobile body). 0a It is shown as follows.

[0066] In the above formula (1), the distance x1 from the reference point at the tip of the moving body to the tip of the gas resistance reduction structure refers to the distance along the surface of the moving body from the reference point at the tip of the moving body to the tip of the gas resistance reduction structure in the direction of travel of the moving body.

[0067] The "reference point of the tip of the moving body" is as described above. The "tip of the gas resistance reduction structure" is the part of the gas resistance reduction structure disposed on the structure that is located foremost relative to the traveling direction of the moving body.

[0068] 4(b), for the rear spoiler 53 (structure 20), the above formula (1) is applied when the height H12 of the rear spoiler 53 (structure 20) is equal to or less than the boundary layer thickness δ0 at the position of the rear spoiler 53 (structure 20). In this case, for the gas drag reduction structure 1b arranged on the rear spoiler 53 (structure 20), the above distance x1 is calculated as the distance x along the surface of the bus 50 (mobile body) from the reference point E0 of the tip of the bus 50 (mobile body) to the tip E12 of the gas drag reduction structure 1b arranged on the rear spoiler 53 (structure 20) in the traveling direction D1 of the bus 50 (mobile body). 1b It is shown as follows.

[0069] In FIG. 6(a), for the roof spoiler 63 (structure 20), the height of the roof spoiler 63 (structure 20) is 0, and the above formula (1) is applied. In this case, in the gas drag reduction structure 1a arranged on the roof spoiler 63 (structure 20), the distance x1 is the distance x along the surface of the truck 60 (mobile body) from the reference point E0 of the tip of the truck 60 (mobile body) to the tip E11 of the gas drag reduction structure 1a arranged on the roof spoiler 63 (structure 20) in the traveling direction D1 of the truck 60 (mobile body). 1a It is shown as follows.

[0070] 6(b), for the loading platform 62 (structure 20), the above formula (1) is applied when the height H11 of the loading platform 62 (structure 20) is equal to or less than the boundary layer thickness δ0 at the position of the loading platform 62 (structure 20). In this case, for the gas drag reduction structure 1a arranged on the loading platform 62 (structure 20), the above distance x1 is calculated as the distance x along the surface of the truck 60 (mobile body) from the reference point E0 of the tip of the truck 60 (mobile body) to the tip E11 of the gas drag reduction structure 1a arranged on the loading platform 62 (structure 20) in the traveling direction D1 of the truck 60 (mobile body). 1a It is shown as follows.

[0071] In FIG. 7(a), for the roof spoiler 72 (structure 20), the height of the roof spoiler 72 (structure 20) is 0, and the above formula (1) is applied. In this case, in the gas drag reduction structure 1a arranged on the roof spoiler 72 (structure 20), the distance x1 is the distance x along the surface of the passenger car 70 (mobile body) from the reference point E0 at the tip of the passenger car 70 (mobile body) to the tip E11 of the gas drag reduction structure 1a arranged on the roof spoiler 72 (structure 20) in the traveling direction D1 of the passenger car 70 (mobile body). 1aIn FIG. 7(b), for the rear spoiler 73 (structure 20), the height of the rear spoiler 73 (structure 20) is 0, and the above formula (1) is applied. In this case, for the gas drag reduction structure 1a arranged on the rear spoiler 73 (structure 20), the distance x1 is the distance x along the surface of the passenger car 70 (mobile body) from the reference point E0 at the tip of the passenger car 70 (mobile body) to the tip E11 of the gas drag reduction structure 1a arranged on the rear spoiler 73 (structure 20) in the traveling direction D1 of the passenger car 70 (mobile body). 1a It is shown as follows.

[0072] In the above formula (2), the distance x2 from the reference point at the tip of the structure to the tip of the gas drag reduction structure refers to the distance along the surface of the structure from the reference point at the tip of the structure to the tip of the gas drag reduction structure in the direction of travel of the moving body.

[0073] The "reference point of the tip of the structure" is as described above. Also, the "tip of the gas drag reduction structure" is as described above.

[0074] 4(b), for the air conditioner 52 (structure 20), if the height H11 of the air conditioner 52 (structure 20) is greater than the boundary layer thickness δ0 at the position of the air conditioner 52 (structure 20), the above formula (2) is applied. In this case, in the gas drag reduction structure 1a arranged in the air conditioner 52 (structure 20), the above distance x2 is calculated as the distance x along the surface of the rear spoiler 53 (structure 20) from the reference point E1 at the tip of the air conditioner 52 (structure 20) to the tip E11 of the gas drag reduction structure 1a arranged in the rear spoiler 53 (structure 20) in the traveling direction D1 of the bus 50 (mobile body). 2a It is shown as follows.

[0075] 6(c), for the air deflector 64 (structure 20), when the height H11 of the air deflector 64 (structure 20) is greater than the boundary layer thickness δ0 at the position of the air deflector 64 (structure 20), the above formula (2) is applied. In this case, in the gas drag reduction structure 1a arranged on the air deflector 64 (structure 20), the above distance x2 is the distance x along the surface of the air deflector 64 (structure 20) from the reference point E1 at the tip of the air deflector 64 (structure 20) to the tip E11 of the gas drag reduction structure 1a arranged on the air deflector 64 (structure 20) in the traveling direction D1 of the truck 60 (mobile body). 2a It is shown as follows.

[0076] The "direction of travel of a moving body" refers to the direction in which gas moves along the surface of the moving body as the moving body moves. For example, if the moving body is an automobile or a railroad vehicle, the moving body can move forward, backward, turn right, turn left, etc., and in this case, the direction of travel of the moving body refers to the direction in which the moving body moves forward. Also, for example, if the moving body is an aircraft, the direction of travel of the moving body refers to the direction in which the moving body moves during flight.

[0077] As described above, in a gas drag reduction structure disposed in a structure, the height of the convex portions of the concave-convex structure may be set based on the boundary layer thickness at the position of the gas drag reduction structure. Specifically, the height of the convex portions is preferably 1 μm or more, more preferably 15 μm or more, even more preferably 20 μm or more, and particularly preferably 50 μm or more. Meanwhile, the height of the convex portions is preferably 200 mm or less, more preferably 150 mm or less, even more preferably 130 mm or less, and particularly preferably 100 mm or less. That is, the height of the convex portions is preferably 1 μm or more and 200 mm or less, more preferably 15 μm or more and 150 mm or less, even more preferably 20 μm or more and 130 mm or less, particularly preferably 20 μm or more and 100 mm or less, and most preferably 50 μm or more and 100 mm or less. As described above, by appropriately adjusting the height of the convex portions within the above range, vortices can be more easily generated near the boundary between the first region and the second region. Furthermore, by having the height of the convex portion within the above range, the benefit of reduced pressure resistance can be made greater than the increase in frictional resistance due to the first region.

[0078] The height H1 of the convex portion 11 refers to the height from the bottom of the recess 12 in the concave-convex structure 10 in the first region 2 to the top of the convex portion 11, as shown in FIG. 1(c), for example. Specifically, as will be described later, when a convex portion in the first region protrudes relative to the surface of the second region, the height of the convex portion refers to the height from the bottom of the recess located between two adjacent convex portions to the top of the convex portion. Furthermore, as will be described later, when a recess in the first region is recessed relative to the surface of the second region, the height of the convex portion refers to the height from the bottom of the recess to the top of the convex portion located between two adjacent recesses.

[0079] Furthermore, when a gas resistance reduction structure is disposed at at least one selected from the group consisting of a corner at the boundary between the front and side surfaces of a moving body, a corner at the boundary between the front and top surfaces of a moving body, a corner at the boundary between the back surface and side surfaces of a moving body, and a corner at the boundary between the back surface and top surfaces of a moving body, other than a structure, it is preferable that the height of the convex portions of the concavo-convex structure in the gas resistance reduction structure disposed at the corner is set based on the boundary layer thickness at the position of the gas resistance reduction structure, which can improve the gas resistance reduction effect in the same way as a gas resistance reduction structure disposed in a structure.

[0080] Specifically, in the gas drag reduction structure arranged at the corner, the height of the convex portion of the concave-convex structure is preferably 0.01% or more and 50% or less, more preferably 0.1% or more and 30% or less, and even more preferably 0.5% or more and 15% or less, when the boundary layer thickness at the position of the gas drag reduction structure is taken as 100%.

[0081] In the gas drag reduction structure disposed at the corner, the boundary layer thickness δ3 at the position of the gas drag reduction structure is calculated by the following formula (4). δ3=0.37(U0x3 / v) -1 / 5 x3(4) In the above formula (4), v represents the dynamic viscosity coefficient of the gas, U0 represents the flow velocity of the gas, and x3 represents the distance from the reference point at the tip of the moving body to the tip of the gas drag reduction structure.

[0082] The dynamic viscosity coefficient v of the gas and the flow velocity U0 of the gas are as described above.

[0083] In the above equation (4), the distance x3 from the reference point at the tip of the moving body to the tip of the gas resistance reduction structure refers to the distance along the surface of the moving body from the reference point at the tip of the moving body to the tip of the gas resistance reduction structure in the direction of travel of the moving body.

[0084] The "reference point of the tip of the moving body" is as described above. The "tip of the gas resistance reduction structure" is the part of the gas resistance reduction structure arranged at the corner that is located foremost relative to the traveling direction of the moving body.

[0085] In FIG. 4(c), in the gas drag reduction structure 1c arranged at the corner which is the boundary between the front and side of the bus 50 (mobile body), the distance x3 is the distance x along the surface of the bus 50 (mobile body) from the reference point E0 of the tip of the bus 50 (mobile body) to the tip E13 of the gas drag reduction structure 1c arranged at the corner in the traveling direction D1 of the bus 50 (mobile body). 3a In the gas drag reduction structure 1c arranged at the corner, which is the boundary between the rear and side of the bus 50 (mobile body), the distance x3 is the distance x along the surface of the bus 50 (mobile body) from the reference point E0 at the tip of the bus 50 (mobile body) to the tip E14 of the gas drag reduction structure 1c arranged at the corner, in the traveling direction D1 of the bus 50 (mobile body). 3b It is shown as follows.

[0086] More specifically, in the gas drag reduction structure disposed at the corner, the height of the convex portions of the concave-convex structure is preferably 1 μm to 200 mm, more preferably 15 μm to 200 mm, even more preferably 20 μm to 150 mm, particularly preferably 20 μm to 100 mm, and most preferably 50 μm to 100 mm. As described above, by appropriately adjusting the height of the convex portions within the above range, vortices can be easily generated near the boundary between the first and second regions. Furthermore, by having the height of the convex portions within the above range, the benefit of pressure drag reduction can be increased compared to the increase in frictional resistance due to the first region.

[0087] (b) Width of the first region In the present disclosure, in a gas resistance reduction structure disposed on a structure, the width of the first region in a direction intersecting the direction of travel of the moving body is set based on the boundary layer thickness at the position of the structure.

[0088] Specifically, in a gas resistance reduction structure disposed in a structure, the width of the first region in a direction intersecting the direction of travel of the moving body is preferably 0.5 to 3 times the boundary layer thickness at the position of the gas resistance reduction structure, and more preferably 1 to 2 times the boundary layer thickness.

[0089] In the gas drag reduction structure disposed in the structure, the boundary layer thickness at the position of the gas drag reduction structure is as described above.

[0090] More specifically, in a gas drag reduction structure disposed in a structure, the width of the first region in a direction intersecting the traveling direction of the moving body is preferably 0.2 mm or more, more preferably 1 mm or more. Meanwhile, the width of the first region in a direction intersecting the traveling direction of the moving body is preferably 700 mm or less, more preferably 100 mm or less. That is, the width of the first region in a direction intersecting the traveling direction of the moving body is preferably 0.2 mm or more and 700 mm or less, more preferably 1 mm or more and 100 mm or less. When the width of the first region in a direction intersecting the traveling direction of the moving body is within the above range, a large vortex V is generated near the boundary between the first region 2 and the second region 3, as shown in FIG. 5(b), for example, and the vortex V can be generated throughout the entire boundary layer.

[0091] In the gas drag reduction structure disposed on the structure, the width of the first region in a direction intersecting the traveling direction of the moving body may be set based on the boundary layer thickness at the position of the structure, and may be the same as or different from the width of the second region in a direction intersecting the traveling direction of the moving body, which will be described later. It is particularly preferable that the width of the first region in a direction intersecting the traveling direction of the moving body and the width of the second region in a direction intersecting the traveling direction of the moving body are the same. In this case, vortices can be generated more efficiently near the boundary between the first region and the second region.

[0092] The width W1 of the first region 2 in the direction D2 intersecting the traveling direction of the moving body refers to the distance from one end to the other end of the first region 2 in the direction D2 intersecting the traveling direction of the moving body, as shown in Figures 1(a) and 1(b), for example. Furthermore, if the surface of the gas drag reduction structure 1 is flat, as shown in Figure 1(b), for example, the width of the first region in the direction intersecting the traveling direction of the moving body refers to the width W1 of the first region 2 on the flat surface in the direction D2 intersecting the traveling direction of the moving body. Furthermore, if the surface of the gas drag reduction structure 1 is curved, as shown in Figure 8(b), for example, the width of the first region in the direction intersecting the traveling direction of the moving body refers to the width W1 of the first region 2 on the curved surface in the direction D2 intersecting the traveling direction of the moving body.

[0093] Furthermore, when a gas resistance reduction structure is disposed at at least one selected from the group consisting of a corner at the boundary between the front and side surfaces of a moving body, a corner at the boundary between the front and top surfaces of a moving body, a corner at the boundary between the back and side surfaces of a moving body, and a corner at the boundary between the back and top surfaces of a moving body, other than a structure, it is preferable that the width of the first region in the direction intersecting the traveling direction of the moving body in the gas resistance reduction structure disposed at the corner is set based on the boundary layer thickness at the position of the gas resistance reduction structure. As with gas resistance reduction structures disposed in structures, the gas resistance reduction effect can be improved.

[0094] Specifically, in the gas resistance reduction structure arranged at the corner, the width of the first region in a direction intersecting the direction of travel of the moving body is preferably 0.5 to 3 times the boundary layer thickness at the position of the gas resistance reduction structure, and more preferably 1 to 2 times the boundary layer thickness at the position of the gas resistance reduction structure.

[0095] In the gas drag reduction structure disposed at the corner, the boundary layer thickness at the position of the gas drag reduction structure is as described above.

[0096] More specifically, in the gas drag reduction structure disposed at the corner, the width of the first region in the direction intersecting the traveling direction of the moving body is preferably 0.2 mm to 700 mm, more preferably 1 mm to 100 mm. When the width of the first region in the direction intersecting the traveling direction of the moving body is within the above range, a large vortex V is generated near the boundary between the first region 2 and the second region 3, as shown in Fig. 5(b), for example, and the vortex V can be generated throughout the entire boundary layer.

[0097] (c) Length of the first region In the gas drag reduction structure of the present disclosure, it is preferable that the length L1 of the first region 2 in the traveling direction D1 of the moving body is equal to or greater than a predetermined value, thereby enabling the vortex V to be efficiently generated near the boundary between the first region 2 and the second region 3.

[0098] The length of the first region in the traveling direction of the moving body is 30 mm or more, preferably 50 mm or more. If the length of the first region in the traveling direction of the moving body is too short, vortices may not be easily generated near the boundary between the first region and the second region, and the effect of suppressing flow separation may be reduced. Furthermore, by having the length of the first region in the traveling direction of the moving body within the above range, vortices can be efficiently generated near the boundary between the first region and the second region. On the other hand, the length of the first region in the traveling direction of the moving body is not particularly limited, but is preferably 1000 mm or less, and more preferably 200 mm or less. If the length of the first region in the traveling direction of the moving body is too long, even if pressure resistance can be reduced, frictional resistance may increase, and the effect of reducing gas resistance may be reduced. Furthermore, manufacturing costs may increase. Specifically, the length of the first region in the traveling direction of the moving body is preferably 30 mm or more and 1000 mm or less, more preferably 50 mm or more and 1000 mm or less, and even more preferably 50 mm or more and 200 mm or less.

[0099] The length L1 of the first region 2 in the traveling direction D1 of the moving body refers to the distance from one end of the first region 2 to the other end of the first region 2 in the traveling direction D1 of the moving body, as shown in FIG. 1(a), for example. Specifically, as will be described later, if a convex portion in the first region protrudes from the surface of the second region, the length of the first region in the traveling direction of the moving body refers to the distance from the end of the convex portion located at one end of the first region to the end of the convex portion located at the other end of the first region in the traveling direction of the moving body. On the other hand, as will be described later, if a concave portion in the first region is recessed from the surface of the second region, the length of the first region in the traveling direction of the moving body refers to the distance from the end of the concave portion located at one end of the first region to the end of the concave portion located at the other end of the first region in the traveling direction of the moving body. Furthermore, if the surface of the gas drag reduction structure 1 is flat, as shown in FIG. 1(c), for example, the length of the first region in the traveling direction of the moving body refers to the length L1 of the first region 2 on the plane in the traveling direction D1 of the moving body, as shown in FIG. 1(a), for example. Furthermore, for example, as shown in Figure 8(a), when the surface of the gas drag reduction structure 1 is curved, the length of the first region in the traveling direction of the moving body refers to the length L1 of the first region 2 on the curved surface in the traveling direction D1 of the moving body.

[0100] (d) Convex and concave portions In addition, in the first region, the convex portions may protrude relative to the surface of the second region, and the concave portions may be recessed relative to the surface of the second region. Figures 2 and 10(b) show examples in which the convex portions 11 in the first region 2 protrude relative to the surface of the second region 3, while Figures 9 and 11(b) show examples in which the concave portions 12 in the first region 2 are recessed relative to the surface of the second region 3.

[0101] In particular, it is preferable that the convex portion protrude from the surface of the second region, which makes it easier to generate vortices near the boundary between the first region and the second region.

[0102] When the convex portions protrude from the surface of the second region, the bottoms of the concave portions 5 are usually located on the same plane as the surface of the second region 3, as shown in Fig. 2 for example. When the concave portions are recessed from the surface of the second region, the tops of the convex portions 11 are usually located on the same plane as the surface of the second region 3, as shown in Fig. 9 for example.

[0103] The first region has a concave-convex structure including convex portions and concave portions, and it is sufficient that the convex portions and concave portions are uniformly distributed in the first region.

[0104] The pattern shape of the convex portions and concave portions in plan view may be, for example, a regular pattern or a random pattern. In the case of a regular pattern, examples include a line pattern, a dot pattern, a lattice pattern, and the like.

[0105] Examples of the line pattern include straight lines and wavy line patterns such as sine waves and triangular waves. Of these, the line pattern is preferably a straight line pattern.

[0106] In the dot pattern, the dots may be arranged in a parallel arrangement or a staggered arrangement, for example.

[0107] Examples of the lattice pattern include a square lattice pattern, a rectangular lattice pattern, a triangular lattice pattern, a hexagonal lattice pattern, a rhombic lattice pattern, and a parallelogram lattice pattern.

[0108] FIG. 2 shows an example in which the pattern shape of the convex portions 11 in a plan view is linear. FIG. 10 shows an example in which the pattern shape of the concave portions 12 in a plan view is linear. FIGS. 10(a) to 10(c) show examples in which the pattern shape of the convex portions 11 in a plan view is a dotted pattern in a staggered arrangement. FIGS. 10(b) and 10(c) are cross-sectional views taken along line AA in FIG. 10(a). FIGS. 11(a) to 11(b) show examples in which the pattern shape of the concave portions 12 in a plan view is a dotted pattern in a staggered arrangement. FIG. 11(b) is a cross-sectional view taken along line AA in FIG. 11(a). FIG. 12 shows an example in which the pattern shape of the convex portions 11 in a plan view is a lattice pattern, a rectangular lattice pattern.

[0109] When the pattern shape of the convex portions and recessed portions in a plan view is linear, the longitudinal direction of the linear pattern of the convex portions and recessed portions preferably intersects with the traveling direction of the moving body, and more preferably is substantially perpendicular to the traveling direction of the moving body, i.e., is substantially parallel to the direction intersecting with the traveling direction of the moving body. Specifically, when the pattern shape of the convex portions and recessed portions is linear, the longitudinal direction of the linear pattern of the convex portions and recessed portions preferably intersects with the traveling direction of the moving body, and is preferably substantially perpendicular to the traveling direction of the moving body, i.e., is substantially parallel to the direction intersecting with the traveling direction of the moving body, as shown in FIG. 3 for example. That is, the first region preferably has convex portions and recessed portions that extend linearly along the direction intersecting with the traveling direction of the moving body. As will be described later, in the moving body, the gas resistance reducing structure is, for example, as shown in FIG. 3(a), parallel to the traveling direction D1 of the moving body, i.e., the flow direction d of the gas F. F It is preferable that the boundary between the first region 2 and the second region 3 is arranged so as to be approximately parallel to the moving body. Therefore, when the longitudinal direction of the linear pattern of the protrusions and recesses intersects with the moving body's direction of travel, the longitudinal direction of the linear pattern of the protrusions and recesses can be made to intersect with the gas flow direction. In such a case, vortices can be more easily generated near the boundary between the first region and the second region. Furthermore, when the longitudinal direction of the linear pattern of the protrusions and recesses is approximately perpendicular to the moving body's direction of travel, the longitudinal direction of the linear pattern of the protrusions and recesses can be made to be approximately perpendicular to the gas flow direction. In such a case, vortices can be even more easily generated near the boundary between the first region and the second region.

[0110] Furthermore, when the longitudinal direction of the linear pattern of the convex portions and concave portions intersects with the traveling direction of the moving body, the angle formed by the longitudinal direction of the linear pattern and the traveling direction of the moving body is preferably, for example, 45° to 135°. Similarly, when the longitudinal direction of the linear pattern of the convex portions and concave portions intersects with the traveling direction of the moving body, the angle formed by the longitudinal direction of the linear pattern and the traveling direction of the moving body is preferably, for example, 45° to 135°.

[0111] "The longitudinal direction of the linear pattern of convex portions and concave portions being substantially perpendicular to the traveling direction of the moving body" means that the angle between the longitudinal direction of the linear pattern and the traveling direction of the moving body is 85° or more and 95° or less. Similarly, "The longitudinal direction of the linear pattern of convex portions and concave portions being substantially perpendicular to the traveling direction of the moving body" means that the angle between the longitudinal direction of the linear pattern and the traveling direction of the moving body is 85° or more and 95° or less.

[0112] The longitudinal direction of a line pattern refers to the direction in which the linear pattern extends in the case of a straight line pattern, and refers to the direction in which the wavy line pattern extends in the case of a wavy line pattern, for example.

[0113] Therefore, the angle between the longitudinal direction of the line-shaped pattern and the traveling direction of the moving body is, for example, preferably 45° to 135°, more preferably 80° to 100°, and even more preferably 85° to 95°. Furthermore, when the line shape is linear, the angle between the longitudinal direction of the linear pattern and the traveling direction of the moving body is, for example, preferably 45° to 135°, more preferably 80° to 100°, and even more preferably 85° to 95°.

[0114] When the pattern shape of the convex portions and concave portions in a planar view is linear, the width of the linear convex portions is preferably, for example, 1 to 2 times the height of the convex portions. Specifically, when the pattern shape of the convex portions is linear, the width of the linear convex portions is preferably 1 to 2 times the height of the convex portions. If the width of the linear convex portions is too small, it may be difficult to form the first region. Furthermore, if the width of the linear convex portions is too large, it may be difficult to sufficiently generate vortices near the boundary between the first region and the second region.

[0115] The width of the linear convex portion is, for example, width W3 of the convex portion 11 as shown in FIGS. 13(a) to 13(i), and refers to the largest width of the convex portion 11.

[0116] Furthermore, when the pattern shape of the convex portions in plan view is linear, the width of the linear recesses is, for example, preferably 1 time or more, and more preferably 4 times or more, the height of the convex portions. On the other hand, the width of the linear recesses is, for example, preferably 12 times or less, and more preferably 10 times or less, the height of the convex portions. On the other hand, the width of the linear recesses is, for example, preferably 1 time or more and 12 times or less, and more preferably 4 times or more and 10 times or less, the height of the convex portions. Specifically, when the pattern shape of the convex portions in plan view is linear, the width of the linear recesses is, for example, preferably 1 time or more and more preferably 4 times or more, the height of the convex portions. On the other hand, the width of the linear recesses is, for example, preferably 12 times or less, and more preferably 10 times or less, the height of the convex portions. On the other hand, the width of the linear recesses is, for example, preferably 12 times or less, and more preferably 10 times or less, the height of the convex portions. On the other hand, the width of the linear recesses is, for example, preferably 1 time or more and 12 times or less, and more preferably 4 times or more and ... If the width of the linear depressions is too small, the density of the protrusions will be high, which may make it difficult to generate sufficient vortices near the boundary between the first and second regions. If the width of the linear depressions is too large, the density of the protrusions will be low, which may make it difficult to generate sufficient vortices near the boundary between the first and second regions. If the width of the linear depressions is between 4 and 10 times the height of the protrusions, vortices can be generated near the boundary between the first and second regions, effectively suppressing flow separation.

[0117] The width of the linear recess is, for example, width W4 of recess 12 as shown in Figures 13(a) to 13(i), and refers to the smallest width of recess 12. For example, in Figure 13(d) and Figures 13(g) to 13(i), the width of recess 12 is zero.

[0118] Furthermore, when the pattern shape of the convex portions and concave portions in plan view is linear, the pitch of the linear convex portions is, for example, preferably at least twice the height of the convex portions, and more preferably at least five times. On the other hand, the pitch of the linear convex portions is, for example, preferably at most 14 times the height of the convex portions, and more preferably at most 12 times. Also, the pitch of the linear convex portions is, for example, preferably at least 2 times but not more than 14 times the height of the convex portions, and more preferably at least 5 times but not more than 12 times. Specifically, when the pattern shape of the convex portions in plan view is linear, the pitch of the linear convex portions is, for example, preferably at least 2 times but not more than 5 times the height of the convex portions. On the other hand, the pitch of the linear convex portions is, for example, preferably at most 14 times but not more than 12 times the height of the convex portions, and more preferably at least 5 times but not more than 12 times. Also, the pitch of the linear convex portions is, for example, preferably at least 2 times but not more than 14 times the height of the convex portions, and more preferably at least 5 times but not more than 12 times. If the pitch of the linear protrusions is too small, the density of the protrusions will be high, which may make it difficult to generate a sufficient vortex near the boundary between the first and second regions, whereas if the pitch of the linear protrusions is too large, the density of the protrusions will be low, which may make it difficult to generate a sufficient vortex near the boundary between the first and second regions.

[0119] The pitch of the linear convex portions is, for example, the pitch P1 of the convex portions 11 as shown in FIGS. 13(a) to 13(i), and refers to the distance between adjacent convex portions 11.

[0120] Furthermore, when the pattern shape of the convex portions in a planar view is dot-shaped, the size of the dot-shaped convex portions in a planar view is preferably, for example, one to two times the height of the convex portions. If the size of the dot-shaped convex portions is too small, it may be difficult to form the first region. If the size of the dot-shaped convex portions is too large, it may be difficult to sufficiently generate vortices near the boundary between the first region and the second region.

[0121] Furthermore, when the pattern shape of the recesses in a planar view is dot-shaped, the size of the dot-shaped recesses in a planar view is, for example, preferably at least 1 time, more preferably at least 4 times, the height of the protrusions. On the other hand, the size of the dot-shaped recesses in a planar view is, for example, preferably at most 12 times, more preferably at most 10 times the height of the protrusions. Furthermore, the size of the dot-shaped recesses in a planar view is, for example, preferably at least 1 time and at most 12 times, more preferably at most 4 times and at most 10 times the height of the protrusions. If the size of the dot-shaped recesses is too small, the density of the protrusions will be high, which may make it difficult to generate sufficient vortices near the boundary between the first and second regions. If the size of the dot-shaped recesses is too large, the density of the protrusions will be low, which may make it difficult to generate sufficient vortices near the boundary between the first and second regions. If the size of the dot-shaped recesses is at least 4 times and at most 10 times the height of the protrusions, vortices will be generated near the boundary between the first and second regions, which may effectively suppress flow separation.

[0122] The size of the dot-shaped convex portions in a plan view refers to, for example, the diameter when the convex portions are circular in plan view, the major axis when the convex portions are elliptical in plan view, and the length of the diagonal when the convex portions are rectangular in plan view. Similarly, the size of the dot-shaped concave portions in a plan view refers to, for example, the diameter when the concave portions are circular in plan view, the major axis when the concave portions are elliptical in plan view, and the length of the diagonal when the concave portions are rectangular in plan view.

[0123] Furthermore, when the pattern shape of the convex portions or concave portions in a planar view is dot-shaped, the pitch of the dot-shaped convex portions or concave portions is, for example, preferably at least twice the height of the convex portions, and more preferably at least five times. On the other hand, the pitch of the dot-shaped convex portions or concave portions is, for example, preferably at most 14 times the height of the convex portions, and more preferably at most 12 times. Furthermore, the pitch of the dot-shaped convex portions or concave portions is, for example, preferably at least 2 times but not more than 14 times the height of the convex portions, and more preferably at least 5 times but not more than 12 times. If the pitch of the dot-shaped convex portions or concave portions is too small, the density of the convex portions will be high, which may make it difficult to sufficiently generate vortices near the boundary between the first and second regions. If the pitch of the dot-shaped convex portions or concave portions is too large, the density of the convex portions will be low, which may make it difficult to sufficiently generate vortices near the boundary between the first and second regions.

[0124] The pitch of the dot-shaped convex portions refers to the distance between adjacent convex portions, and the pitch of the dot-shaped concave portions refers to the distance between adjacent concave portions.

[0125] Furthermore, when the planar pattern of the convex portions is a grid, the width of the grid-shaped convex portions is preferably, for example, one to two times the height of the convex portions. If the width of the grid-shaped convex portions is too small, it may be difficult to form the first region. If the width of the grid-shaped convex portions is too large, it may be difficult to sufficiently generate vortices near the boundary between the first region and the second region.

[0126] Furthermore, when the pattern shape of the convex portions in a planar view is a grid, the spacing between the grid-shaped convex portions is, for example, preferably at least 1 time, and more preferably at least 4 times, the height of the convex portions. On the other hand, the spacing between the grid-shaped convex portions is, for example, preferably at most 12 times, and more preferably at most 10 times, the height of the convex portions. Furthermore, the spacing between the grid-shaped convex portions is, for example, preferably at least 1 time and at most 12 times, and more preferably at least 4 times and at most 10 times, the height of the convex portions. If the spacing between the grid-shaped convex portions is too small, the density of the convex portions will be high, which may make it difficult to generate sufficient vortices near the boundary between the first and second regions. If the spacing between the grid-shaped convex portions is too large, the density of the convex portions will be low, which may make it difficult to generate sufficient vortices near the boundary between the first and second regions. Furthermore, if the spacing between the grid-shaped convex portions is at least 4 times and at most 10 times the height of the convex portions, vortices will be generated near the boundary between the first and second regions, and flow separation can be effectively suppressed.

[0127] Furthermore, when the pattern shape of the recesses in a planar view is a grid, the width of the grid-shaped recesses is, for example, preferably at least 1 time, and more preferably at least 4 times, the height of the protrusions. On the other hand, the width of the grid-shaped recesses is, for example, preferably at most 12 times, and more preferably at most 10 times the height of the protrusions. Furthermore, the width of the grid-shaped recesses is, for example, preferably at least 1 time and at most 12 times, and more preferably at most 4 times and at most 10 times the height of the protrusions. If the width of the grid-shaped recesses is too small, the density of the protrusions will be high, which may make it difficult to generate sufficient vortices near the boundary between the first and second regions. If the width of the grid-shaped recesses is too large, the density of the protrusions will be low, which may make it difficult to generate sufficient vortices near the boundary between the first and second regions. Furthermore, if the width of the grid-shaped recesses is at least 4 times and at most 10 times the height of the protrusions, vortices will be generated near the boundary between the first and second regions, which may effectively suppress flow separation.

[0128] Furthermore, when the planar pattern of the convex portions or concave portions is a lattice pattern, the pitch of the lattice-shaped convex portions or concave portions is, for example, preferably at least twice the height of the convex portions, and more preferably at least five times. On the other hand, the pitch of the lattice-shaped convex portions or concave portions is, for example, preferably at most 14 times the height of the convex portions, and more preferably at most 12 times. Furthermore, the pitch of the lattice-shaped convex portions or concave portions is, for example, preferably at least 2 times but not more than 14 times the height of the convex portions, and more preferably at least 5 times but not more than 12 times. If the pitch of the lattice-shaped convex portions or concave portions is too small, the density of the convex portions will be high, which may make it difficult to generate sufficient vortices near the boundary between the first and second regions. If the pitch of the lattice-shaped convex portions or concave portions is too large, the density of the convex portions will be low, which may make it difficult to generate sufficient vortices near the boundary between the first and second regions.

[0129] The dimensions of the first region, the convex portion, and the concave portion are measured by a laser displacement sensor.

[0130] Furthermore, the cross-sectional shapes of the convex portions and concave portions are not particularly limited, and examples thereof include rectangular, trapezoidal, triangular, semicircular, and semi-elliptical shapes. Fig. 13(a) shows an example in which the cross-sectional shapes of the convex portions 11 and concave portions 12 are rectangular. Fig. 13(b) shows an example in which the cross-sectional shapes of the convex portions 11 and concave portions 12 are trapezoidal. Figs. 13(c) to 13(e) show an example in which the cross-sectional shape of the convex portions 11 is triangular. Fig. 13(f) shows an example in which the cross-sectional shape of the convex portions 11 is semi-elliptical. Figs. 13(g) to 13(h) show an example in which the cross-sectional shape of the concave portions 12 is triangular. Fig. 13(i) shows an example in which the cross-sectional shape of the concave portions 12 is semicircular.

[0131] Among these, the cross-sectional shape of the convex or concave portions is preferably trapezoidal, semicircular, or semi-elliptical, as these shapes make it easy to form the first region and can increase the durability of the first region.

[0132] Furthermore, it is preferable that the protrusion has a rounded shape, that is, a curved surface, in the portion extending from the top to the side of the protrusion and connected to the top.

[0133] Figures 14(a) and 14(b) are schematic cross-sectional views illustrating protrusions in the gas drag reduction structure, where Figure 14(a) is a schematic cross-sectional view of the protrusions in a direction intersecting the traveling direction of the moving body, and Figure 14(b) is a schematic cross-sectional view of the protrusions in the traveling direction of the moving body.

[0134] As illustrated in FIGS. 14(a) and 14(b), the protrusions 11 have a rounded portion 11R, which is a portion extending from the top 11T to the side 11S of the protrusions 11 and is connected to the top 11T. That is, the protrusions 11 have a curved surface at the portion 11R. When the protrusions 11 have a rounded portion 11R, the abrasion resistance and wear resistance of the protrusions 11 can be improved. Furthermore, the frictional resistance at the portion 11R on the boundary side of the protrusions 11 against vortices generated at the boundary between the first and second regions can be suppressed. Therefore, it is expected that the effect of the vortex, i.e., the effect of suppressing gas from separating from the surface, will be further enhanced.

[0135] In the above-mentioned portion of the convex portion, the radius of curvature of the curved surface is, for example, preferably 10 μm or more, more preferably 20 μm or more. On the other hand, the radius of curvature of the curved surface is, for example, preferably 400 μm or less, more preferably 200 μm or less. Specifically, the radius of curvature of the curved surface is preferably 10 μm or more and 400 μm or less, more preferably 20 μm or more and 200 μm or less. If the radius of curvature of the curved surface is excessively small, it may be difficult to improve the scratch resistance and abrasion resistance of the gas drag reduction structure. Furthermore, if the radius of curvature of the curved surface is excessively large, the height of the convex portion must also be increased. If the height of the convex portion exceeds a size suitable for reducing gas drag, the gas drag reduction effect may be insufficient.

[0136] The radius of curvature of the curved surface at the above-mentioned portion of the convex portion refers to the radius of curvature of the curve at the above-mentioned portion of the convex portion in a cross section in the thickness direction of the gas drag reduction structure. For example, Fig. 14(a) is a cross section in the thickness direction of the gas drag reduction structure, which is a cross section of the convex portion in a direction intersecting the traveling direction of the moving body. Also, for example, Fig. 14(b) is a cross section in the thickness direction of the gas drag reduction structure, which is a cross section of the convex portion in the traveling direction of the moving body. In Fig. 14(a) and Fig. 14(b), the radius of curvature of the curved surface at the above-mentioned portion 11R of the convex portion 11 is the radius of curvature r1 of the curve at the above-mentioned portion 11R of the convex portion 11.

[0137] Furthermore, the first region has a plurality of convex or concave portions, which are appropriately set to satisfy the above-described dimensions of the first region, the convex portions, and the concave portions. Specifically, the number of convex or concave portions in the first region is 14 or more, or may be 83 or more, or 181 or more. On the other hand, the number of convex or concave portions may be, for example, 1500 or less, or may be 714 or less, or may be 200 or less. Specifically, the number of convex or concave portions may be 14 or more and 1500 or less, or may be 83 or more and 714 or less, or may be 181 or more and 200 or less. By keeping the number of convex or concave portions within the above range, it is possible to maximize the reduction in pressure resistance and minimize the increase in frictional resistance. This makes it possible to maximize the gas resistance reduction effect.

[0138] (e) Shape of the first region The planar shape of the first region is not particularly limited as long as it can generate a vortex near the boundary between the first region and the second region, and examples thereof include a rectangular shape and an arc shape. For example, Fig. 1 shows an example in which the planar shape of the first region 2 is rectangular, and Fig. 15 shows an example in which the planar shape of the first region 2 is rectangular and an arc shape. Among these, a rectangular shape is preferable for the planar shape of the first region.

[0139] (2)Second area In the gas drag reduction structure of the present disclosure, the second region is adjacent to the first region.

[0140] In the present disclosure, in a gas resistance reduction structure disposed on a structure, the width of the second region in a direction intersecting the traveling direction of the moving body is set based on the boundary layer thickness at the position of the structure.

[0141] Specifically, in a gas resistance reduction structure disposed in a structure, the width of the second region in a direction intersecting the direction of travel of the moving body is preferably 0.5 to 3 times the boundary layer thickness at the position of the gas resistance reduction structure, and more preferably 1 to 2 times the boundary layer thickness.

[0142] In the gas drag reduction structure disposed in the structure, the boundary layer thickness at the position of the gas drag reduction structure is as described above.

[0143] More specifically, in a gas drag reduction structure disposed on a structure, the width of the second region in a direction intersecting the traveling direction of the moving body is preferably 0.2 mm or more, more preferably 1 mm or more. On the other hand, the width of the second region in a direction intersecting the traveling direction of the moving body is preferably 700 mm or less, more preferably 100 mm or less. That is, the width of the second region in a direction intersecting the traveling direction of the moving body is preferably 0.2 mm or more and 700 mm or less, more preferably 1 mm or more and 100 mm or less. When the width of the second region in a direction intersecting the traveling direction of the moving body is within the above range, a large vortex V is generated near the boundary between second region 2 and second region 3, as shown in FIG. 5(b), for example, and the vortex V can be generated throughout the entire boundary layer.

[0144] The width W2 of the second region 3 in the direction D2 intersecting the traveling direction of the moving body refers to the distance from one end of the second region 3 to the other end of the second region 3 in the direction D2 intersecting the traveling direction of the moving body, for example, as shown in Figures 1(a) and 1(b) when the second region 3 is located between adjacent first regions 2. Furthermore, for example, as shown in Figure 1(b), if the surface of the gas drag reduction structure 1 is flat, the width of the second region in the direction intersecting the traveling direction of the moving body refers to the width W2 of the second region 3 on the flat surface in the direction D2 intersecting the traveling direction of the moving body. Furthermore, for example, as shown in Figure 8(b), if the surface of the gas drag reduction structure 1 is curved, the width of the second region in the direction intersecting the traveling direction of the moving body refers to the width W2 of the second region 3 on the curved surface in the direction D2 intersecting the traveling direction of the moving body.

[0145] Furthermore, when a gas resistance reduction structure is disposed at at least one selected from the group consisting of a corner at the boundary between the front and side surfaces of a moving body, a corner at the boundary between the front and top surfaces of a moving body, a corner at the boundary between the back and side surfaces of a moving body, and a corner at the boundary between the back and top surfaces of a moving body, other than a structure, it is preferable that the width of the second region in the direction intersecting the traveling direction of the moving body in the gas resistance reduction structure disposed at the corner is set based on the boundary layer thickness at the position of the gas resistance reduction structure. As with gas resistance reduction structures disposed in structures, the gas resistance reduction effect can be improved.

[0146] Specifically, in the gas resistance reduction structure arranged at the corner, the width of the second region in a direction intersecting the direction of travel of the moving body is preferably 0.5 to 3 times, and more preferably 1 to 2 times, the boundary layer thickness at the position of the gas resistance reduction structure.

[0147] In the gas drag reduction structure disposed at the corner, the boundary layer thickness at the position of the gas drag reduction structure is as described above.

[0148] More specifically, in the gas drag reduction structure disposed at the corner, the width of the second region in the direction intersecting the traveling direction of the moving body is preferably 0.2 mm to 700 mm, more preferably 1 mm to 100 mm. When the width of the second region in the direction intersecting the traveling direction of the moving body is within the above range, a large vortex V is generated near the boundary between second region 2 and second region 3, as shown in Fig. 5(b), for example, and the vortex V can be generated throughout the entire boundary layer.

[0149] (3) Area 1 and Area 2 The gas drag reduction structure according to the present disclosure has a first region and a second region adjacent to the first region, and the first region and the second region extend in a band shape in the traveling direction of the moving body.

[0150] In the present disclosure, since vortices are generated near the boundary between the first region and the second region, it is sufficient to arrange at least one first region and at least one second region. In particular, it is preferable that the first region and the second region are arranged alternately in a direction intersecting the traveling direction of the moving body.

[0151] When the first and second regions are alternately arranged in a direction intersecting the traveling direction of the mobile body, for example, the first and second regions may be alternately arranged parallel to the traveling direction of the mobile body, or alternately arranged non-parallel to the traveling direction of the mobile body. For example, FIG. 1(a) shows an example in which the first regions 2 and the second regions 3 are alternately arranged parallel to the traveling direction D2 intersecting the traveling direction of the mobile body, and FIG. 15 shows an example in which the first regions 2 and the second regions 3 are alternately arranged non-parallel to the traveling direction D2 intersecting the traveling direction of the mobile body. For example, when the gas drag reduction structure is applied to a three-dimensional curved surface of a mobile body, the first and second regions may be alternately arranged non-parallel to the traveling direction of the mobile body. In particular, it is preferable that the first and second regions be alternately arranged parallel to the traveling direction of the mobile body.

[0152] (4) The direction of travel of the moving object and the direction intersecting the direction of travel of the moving object The direction intersecting the traveling direction of the moving body may be any direction as long as it intersects with the traveling direction of the moving body, but it is preferable that it be perpendicular to the traveling direction of the moving body. The angle between the traveling direction of the moving body and the direction intersecting with the traveling direction of the moving body is, for example, preferably 85° to 95°, and more preferably 90°.

[0153] The gas resistance reduction structure is preferably arranged so that the angle formed by the boundary line between the first region and the second region and the traveling direction of the moving body is, for example, not less than −15° and not more than 15°.

[0154] In particular, it is more preferable that the gas drag reduction structure be arranged so that the boundary between the first region 2 and the second region 3 is approximately parallel to the traveling direction D1 of the moving body, as shown in Figure 1(a), for example. This makes it easier to generate vortices near the boundary between the first region and the second region, and suppresses flow separation.

[0155] The boundary between the first and second regions being approximately parallel to the traveling direction of the moving body means that the angle between the boundary between the first and second regions and the traveling direction of the moving body is between -5° and 5°.

[0156] Therefore, it is preferable that the gas resistance reduction structure is arranged so that the angle between the boundary line between the first and second regions and the direction of travel of the moving body is, for example, between -15° and 15°, particularly between -10° and 10°, and particularly between -5° and 5°.

[0157] (5) Configuration of the gas drag reduction structure In the present disclosure, the gas drag reduction structure may be configured as a separate body from the moving body, or may be configured as an integral part of the moving body.

[0158] Below, the case where the gas resistance reduction structure is separate from the moving body and the case where the gas resistance reduction structure is integrated with the moving body will be described separately.

[0159] (a) When the gas drag reduction structure is separate from the moving body When the gas resistance reduction structure is configured as a separate body from the moving body, for example, a member having the gas resistance reduction structure on its surface can be used and disposed on the surface of the moving body.

[0160] Examples of members having a gas resistance reducing structure on their surface include resin members having a gas resistance reducing structure on their surface, metal members having a gas resistance reducing structure on their surface, and ceramic members having a gas resistance reducing structure on their surface.

[0161] As will be described later, when the resin member is a resin film and when the metal member is a metal sheet, these members are usually attached to the surface of the moving body. In this case, the moving body becomes a moving body to which the gas resistance reduction structure is attached.

[0162] Furthermore, as will be described later, when the resin member is a resin molded product, when the metal member is a metal part, and when the ceramic member is a ceramic molded product, these members are usually attached to the surface of the moving body or mechanically joined by caulking, screws, etc. In this case, the moving body becomes a moving body equipped with a gas drag reduction structure.

[0163] (i) Resin materials Examples of resin members having a gas resistance reducing structure on their surface include resin films having a gas resistance reducing structure on their surface, and resin molded articles having a gas resistance reducing structure on their surface.

[0164] (i-1) Resin film The resin film has a gas resistance reducing structure on the surface.

[0165] (i-1-1) Textured resin film The resin film may have at least a concave-convex resin film having a gas resistance reducing structure on the surface thereof.

[0166] The uneven resin film may have at least a resin substrate. The uneven resin film may have a gas resistance-reducing structure on its surface. For example, in an uneven resin film 31, the uneven structure of the first region 2 may be integral with the resin substrate 32 as shown in FIGS. 16(a) and 16(b). Alternatively, the uneven structure of the first region 2 may be formed separately from the resin substrate 32 as shown in FIGS. 16(c) to 16(f). When the uneven structure of the first region is formed separately from the resin substrate, the bottoms of the recesses 12 of the uneven structure of the first region 2 and the second region 3 may be on the surface of the resin substrate 32 as shown in FIGS. 16(c) and 16(d). Alternatively, a resin layer 33 may be disposed on one surface of the resin substrate 32, and the resin layer 33 may have the first region 2 and the second region 3 as shown in FIGS. 16(e) to 16(f).

[0167] The first region may be transparent or opaque.

[0168] The material for the concave-convex structure of the first region can be a resin. When the concave-convex structure of the first region is integrally formed with the resin substrate, the material for the concave-convex structure of the first region is the same as the material for the resin substrate described below. When the concave-convex structure of the first region is formed separately from the resin substrate, examples of the material for the concave-convex structure of the first region include a cured product of an ionizing radiation-curable resin composition such as an ultraviolet-curable resin composition or an electron beam-curable resin composition, or a curable resin composition such as a thermosetting resin composition, and a thermoplastic resin.

[0169] Furthermore, the concave-convex structure of the first region may contain additives such as ultraviolet absorbers, antioxidants, plasticizers, stabilizers, lubricants, fillers, colorants, processing aids, antistatic agents, and flame retardants, as needed. When the concave-convex structure of the first region contains an ultraviolet absorber, weather resistance can be improved.

[0170] The method for forming the uneven structure of the first region may be, for example, a method for forming an uneven structure on a resin substrate, or a method for forming an uneven shape on one surface of a resin substrate.

[0171] Examples of methods for forming a relief structure on a resin substrate include a method in which a curable resin composition is applied to a resin substrate in a predetermined pattern and then cured; a photopolymer method (2P method) in which an ultraviolet-curable resin composition is applied to a resin substrate, a mold is pressed against the coating, ultraviolet light is irradiated to cure the ultraviolet-curable resin composition, and then the resin is peeled off from the mold; a lithography method in which an ionizing radiation-curable resin composition is applied to a resin substrate, and the resin substrate is irradiated with ionizing radiation such as ultraviolet light or an electron beam in a pattern and developed; and a method in which a resin layer is formed on a resin substrate and the surface of the resin layer is embossed. Alternatively, a resin layer with an embossed surface may be separately prepared and then laminated on the resin substrate.

[0172] In the case of a method in which a curable resin composition is applied to a resin substrate in a predetermined pattern and then cured, the method for applying the curable resin composition is not particularly limited as long as it can be applied in a desired pattern, and examples thereof include an inkjet method, a screen printing method, etc. In addition, in the case of the 2P method or the lithography method, the method for applying the curable resin composition is not particularly limited as long as it can be applied uniformly, and any known application method can be used.

[0173] In the case of the embossing method, the material of the resin layer is not particularly limited as long as it is embossable, and a thermoplastic resin can be used. In this case, the thickness of the resin layer is not particularly limited as long as it is greater than the height of the convex portions of the concave-convex structure of the first region, and is approximately 30 μm to 300 μm.

[0174] Examples of methods for forming an uneven shape on one surface of a resin substrate include embossing such as single-side embossing or double-side embossing, and laser processing.

[0175] When the resin substrate is integrally formed with the concave-convex structure of the first region, the material of the resin substrate can be, for example, a thermoplastic resin, and can be appropriately selected from general-purpose plastics and engineering plastics. Among them, vinyl chloride resin is preferred from the viewpoints of weather resistance and abrasion resistance.

[0176] Furthermore, the resin substrate may contain additives such as plasticizers, stabilizers, lubricants, fillers, colorants, processing aids, UV absorbers, antioxidants, antistatic agents, and flame retardants, as needed. When the resin substrate is integrally formed with the uneven structure of the first region and contains an UV absorber, weather resistance can be improved.

[0177] The resin substrate may be transparent or opaque.

[0178] The thickness of the resin substrate is not particularly limited, but is about 80 μm or more and 350 μm or less.

[0179] (i-1-2) Other configurations of resin film The resin film may further have other components in addition to the uneven resin film.

[0180] (Adhesive layer) 17(a), the resin film 30 may have an adhesive layer 34 on the surface of the first region 2 of the uneven resin film 31 opposite to the uneven structure. The adhesive layer is a layer for attaching the resin film to the surface of a moving object. By having the adhesive layer on the resin film, the resin film can be easily attached to the surface of a moving object.

[0181] The adhesive used in the adhesive layer is appropriately selected depending on the use of the resin film, and examples thereof include acrylic adhesives, urethane adhesives, silicone adhesives, rubber adhesives, and vinyl ether adhesives.

[0182] The adhesive layer may or may not have removability, but is preferably removably. When the adhesive layer has removability, the resin film can be reattached to the surface of the movable body, and when the resin film is reattached or removed, the resin film can be peeled from the movable body without leaving any adhesive residue.

[0183] The term "removable" refers to the property that after a resin film is attached to the surface of a mobile object, it can be easily removed without destroying the mobile object and without leaving any adhesive on the surface of the mobile object.

[0184] The adhesive layer may also contain a colorant. By containing a colorant in the adhesive layer, it is possible to impart shielding properties. For example, when a design is applied to the surface of a mobile object, if the adhesive layer contains a colorant and the resin film further has a printed layer as described below, the design can be hidden and a new design can be applied by attaching the resin film to the surface of the mobile object.

[0185] The thickness of the adhesive layer is not particularly limited and is appropriately selected depending on the application, etc. For example, when the resin film is used as a wrapping film or marking film for a moving body such as an automobile, a train, or an airplane, the thickness of the adhesive layer is about 5 μm or more and 50 μm or less. If the thickness of the adhesive layer is too thin, there is a possibility that the adhesion to the moving body will be insufficient.

[0186] Examples of methods for forming the adhesive layer include a method of applying an adhesive composition and a method of laminating an adhesive film.

[0187] (Printing layer) The resin film may have a printed layer on the surface opposite to the first region of the uneven resin film. By having a printed layer on the resin film, it is possible to impart design properties.

[0188] The print layer can display information such as letters, numbers, symbols, pictures, patterns, and marks.

[0189] The printing layer may be formed, for example, by printing directly on the resin substrate of the uneven resin film, or by printing on a support layer 35, as shown in FIG. 17(b), to form a printing layer 36. The printing layer may be arranged in a pattern on the resin substrate or support layer, or may be arranged over the entire surface of the resin substrate or support layer. The printing method is not particularly limited.

[0190] The support layer is not particularly limited as long as it can be printed, and for example, a resin substrate can be used.

[0191] The support layer may also contain a colorant. By including a colorant in the support layer, it is possible to impart shielding properties. For example, when a design is applied to the surface of a mobile object, if the resin film has a printed layer and the support layer contains a colorant, the design can be hidden and a new design can be applied by attaching a resin film to the surface of the mobile object.

[0192] The thickness of the support layer is not particularly limited and may be appropriately selected depending on the application.

[0193] Furthermore, when forming a printed layer by printing on a support layer, for example, as shown in Figure 17(b), a printed sheet having a support layer 35 and a printed layer 36 arranged on one side of the support layer 63 may be separately prepared, and this printed sheet may be attached to the uneven resin film 31 via a second adhesive layer 37, or the printed layer, resin substrate, and resin layer may be formed in that order on the support layer.

[0194] (protective layer) The resin film may have a protective layer on the surface of the first region of the uneven resin film facing the uneven structure, which can protect the first region and improve abrasion resistance.

[0195] When a protective layer is disposed on the surface of the first region of the uneven resin film facing the uneven structure, it is preferable that the dimensions of the unevenness on the surface of the resin film facing the protective layer satisfy the dimensions of the uneven structure of the first region described above.

[0196] The protective layer may be made of, for example, a resin, of which electron beam curable resin and fluororesin are preferred from the viewpoints of weather resistance and abrasion resistance.

[0197] Furthermore, the protective layer may contain additives such as ultraviolet absorbers, antioxidants, plasticizers, stabilizers, lubricants, fillers, colorants, processing aids, antistatic agents, and flame retardants, as required. When the protective layer contains an ultraviolet absorber, weather resistance can be improved.

[0198] The thickness of the protective layer is preferably, for example, 0.01 μm or more and 10 μm or less.

[0199] (i-1-3) Resin film placement method As a method for disposing a resin film on the surface of a moving body, for example, a method of adhering it using a pressure sensitive adhesive or adhesive agent can be mentioned.

[0200] (i-2) Resin molded products The resin molded article has a gas resistance reducing structure on the surface.

[0201] The material for the resin molded product may be a thermoplastic resin, which may be appropriately selected from general-purpose plastics and engineering plastics, among which acrylic resins and polycarbonates are preferred from the viewpoints of weather resistance and abrasion resistance.

[0202] The method for producing a resin molded article is not particularly limited as long as it is a method that can produce a resin molded article having a gas drag reducing structure on the surface, and examples thereof include injection molding and extrusion molding.

[0203] Methods for placing a resin molded product on the surface of a moving body include, for example, adhesion using a pressure sensitive adhesive or adhesive, caulking, screw fastening, and the like.

[0204] (ii) Metallic components Examples of metal members having a gas resistance reducing structure on their surface include metal sheets having a gas resistance reducing structure on their surface, and metal parts having a gas resistance reducing structure on their surface.

[0205] (ii-1) Metal sheet The metal sheet may have at least a metal layer having a gas drag reduction structure on its surface.

[0206] The material for the metal layer is not particularly limited as long as it is a material that can produce a metal layer having a gas drag reduction structure on its surface, and examples include aluminum, aluminum alloys, titanium, titanium alloys, copper, iron, and stainless steel.

[0207] Examples of methods for forming the first region on the surface of the metal layer include press processing (embossing), rolling, end mill processing, laser processing, and lithography.

[0208] The thickness of the metal layer is not particularly limited and may be appropriately selected depending on the intended use.

[0209] (ii-1-2) Other configurations of metal sheets The metal sheet may further include other components in addition to the metal layer.

[0210] (Adhesive layer) The metal sheet may have an adhesive layer on the surface of the metal layer opposite to the first region. The adhesive layer is a layer for attaching the metal sheet to the surface of a moving body. By having the adhesive layer on the metal sheet, the metal sheet can be easily attached to the surface of a moving body.

[0211] The adhesive layer is the same as the adhesive layer used in the resin film.

[0212] (ii-1-3) Metal sheet placement method As a method for placing a metal sheet on the surface of a moving body, for example, a method of adhering it using a pressure sensitive adhesive or adhesive can be mentioned.

[0213] (ii-2) Metal parts The metal part has a gas drag reduction structure on the surface.

[0214] The material for the metal parts is not particularly limited as long as it is a material that can be used to obtain metal parts having a gas resistance reducing structure on the surface, and examples include aluminum, aluminum alloys, titanium, titanium alloys, copper, iron, stainless steel, etc.

[0215] Methods for forming the first region on the surface of a metal part include, for example, press processing (embossing), end mill processing, laser processing, and modeling using a metal 3D printer.

[0216] Methods for placing metal parts on the surface of a moving body include, for example, welding, bonding using a pressure sensitive adhesive or adhesive, crimping, screw fastening, and the like.

[0217] (iii) Ceramic components Examples of ceramic members having a gas resistance reducing structure on the surface include ceramic molded articles having a gas resistance reducing structure on the surface.

[0218] As the material for the ceramic molded product, for example, fine ceramics can be used.

[0219] The method for producing a ceramic molded article is not particularly limited as long as it is a method capable of producing a ceramic molded article having a gas drag reducing structure on the surface thereof, and examples thereof include injection molding and extrusion molding.

[0220] Methods for placing the ceramic molded product on the surface of the moving body include, for example, adhesion using a pressure sensitive adhesive or adhesive, caulking, screw fastening, and the like.

[0221] (b) When the gas drag reduction structure is integrated with the moving body When the gas resistance reduction structure is configured as an integral part of a moving body, the gas resistance reduction structure is formed directly on the surface of the moving body. When the gas resistance reduction structure is formed directly on the surface of a moving body, for example, the gas resistance reduction structure can be formed directly on the surface of a vehicle body or part of an automobile, railway vehicle, or the like, or the body or part of an aircraft.

[0222] The material that constitutes the gas drag reduction structure is appropriately selected depending on the vehicle body or its parts, or the aircraft or its parts, on which the gas drag reduction structure is formed, and examples thereof include metallic materials such as metals and alloys, resin materials such as resins and fiber-reinforced resins, and ceramic materials such as glass and fine ceramics.

[0223] The method for forming the gas drag reduction structure directly on the surface of the moving body is appropriately selected depending on the material and the like.

[0224] For example, in the case of metal materials, examples of methods include end mill processing, laser processing, and shaping using a metal 3D printer. In addition, in the case of metal materials, first, the above-mentioned uneven resin film is used as an original plate, and a water-soluble resin composition is applied to the surface of the uneven structure side of the uneven resin film (original plate), dried and solidified, and then peeled off from the uneven resin film (original plate) to prepare a stamper made of the water-soluble resin film. Next, a surface coating agent is applied to the surface of the moving body, and the water-soluble resin film (stamper) is pressed against the coating film. The surface coating agent is cured, and then the water-soluble resin film (stamper) is dissolved and removed with water. In this method, for example, a common paint used for painting automobiles, railway vehicles, aircraft, etc. can be used as the surface coating agent. In addition, in the case of metal materials, a method can also be used in which an ultraviolet-curable paint is applied to the surface of the moving body, a stamper is pressed against the coating film, ultraviolet light is irradiated to cure the ultraviolet-curable paint, and the stamper is then peeled off to form an uneven shape. In this method, any stamper that transmits ultraviolet light can be used, for example, a resin stamper.

[0225] For example, in the case of a resin material, examples of the method include embossing such as single-sided embossing or double-sided embossing, laser processing, etc. For example, in the case of a ceramic material, examples of the method include laser processing, etc.

[0226] (6) Location of the gas drag reduction structure In the present disclosure, the gas drag reduction structure is disposed on a structure. The gas drag reduction structure is disposed in a portion of the structure where flow separation is likely to occur, i.e., a portion that is hit by the gas flow as the moving body travels. Specifically, the gas drag reduction structure is disposed in the front portion of the structure with respect to the traveling direction of the moving body. It is sufficient that the gas drag reduction structure is disposed in at least a portion of the front portion of the structure.

[0227] To reduce gas resistance, the corners of a moving body, which are the boundaries between the front and top surfaces of the moving body, the corners of the boundaries between the front and side surfaces of the moving body, and the corners of the boundaries between the front and bottom surfaces of the moving body, are often rounded. Similarly, to reduce gas resistance, the corners of a structure, which are the boundaries between the front and top surfaces of the structure, the corners of the boundaries between the front and side surfaces of the structure, and the corners of the boundaries between the front and bottom surfaces of the structure, are often rounded. In this case, as shown in FIGS. 18(a) to 18(c), for example, a structure 20 has, from the top surface of the structure 20 toward the front, a flat portion 22 and a curved portion 23 located in front of and connected to the flat portion 22. Similarly, the structure has, from the side surfaces of the structure toward the front, a flat portion and a curved portion located in front of and connected to the flat portion.

[0228] When the gas drag reduction structure is disposed at the front of the structure with respect to the traveling direction of the moving object, the gas drag reduction structure 1 may be disposed across the flat portion 22 and the curved portion 23 of the structure 20, as exemplified in Figure 18(a), or the gas drag reduction structure 1 may be disposed only on the flat portion 22 of the structure 20, as exemplified in Figure 18(b), or the gas drag reduction structure 1 may be disposed only on the curved portion 23 of the structure 20, as exemplified in Figure 18(c). Furthermore, when the corner that is the boundary between the front surface and the top surface of the structure 20 is an acute angle, the gas drag reduction structure 1 is disposed only on the flat portion 22 of the structure 20, as exemplified in Figure 18(d).

[0229] Furthermore, flow separation is more likely to occur near the point where the radius of curvature changes at the front of the structure. Therefore, among the above, as exemplified in Figures 18(a) and 18(c), the gas drag reduction structure 1 is preferably disposed at least at the curved portion 23 of the structure 20 at the front of the structure 20. In other words, the gas drag reduction structure is preferably disposed so as to straddle the point where the radius of curvature changes at the front of the structure. By disposing the gas drag reduction structure in this manner, flow separation can be effectively suppressed.

[0230] In addition to the structure, the gas resistance reduction structure is preferably disposed at at least one selected from the group consisting of a corner at the boundary between the front and side surfaces of the moving body, a corner at the boundary between the front and top surfaces of the moving body, a corner at the boundary between the back and side surfaces of the moving body, and a corner at the boundary between the back and top surfaces of the moving body. Flow separation is likely to occur at these corners. Therefore, by disposing the gas resistance reduction structure at these corners, the gas resistance reduction effect can be enhanced.

[0231] The gas drag reduction structure is disposed in a portion of the corner where flow separation is likely to occur. When a structure is disposed in a corner that is the boundary between the back surface and side surface of the moving body, the gas drag reduction structure is disposed in the corner, at least on the side surface of the moving body. Furthermore, when a structure is disposed in a corner that is the boundary between the back surface and top surface of the moving body, the gas drag reduction structure is disposed in the corner, at least on the top surface of the moving body. It is sufficient that the gas drag reduction structure is disposed in at least a portion of the corner.

[0232] The corners may be sharp or rounded. In particular, it is preferable that the corners are rounded. This is because when the corners are rounded, the gas resistance reducing effect of the gas resistance reducing structure is enhanced.

[0233] In the bus 50 (mobile body) shown in Figures 4(a) to 4(c), gas drag reduction structures 1c are arranged at corners that form the boundaries between the front and side of the bus 50 (mobile body) and at corners that form the boundaries between the back and side of the bus 50 (mobile body), i.e., on the front and rear sides of the bus 50. In the truck 60 (mobile body) shown in Figure 6(a), gas drag reduction structures 1c are arranged at corners that form the boundaries between the front and side of the truck 60 (mobile body) and at corners that form the boundaries between the back and side of the truck 60 (mobile body), i.e., on the front side of the cabin 61, the rear side of the cabin 61, and the rear side of the cargo bed 62. In the truck 60 (mobile body) shown in Figure 6(b), gas resistance reduction structures 1c are arranged at corners that form the boundaries between the front and side of the truck 60 (mobile body) and at corners that form the boundaries between the back and side of the truck 60 (mobile body), i.e., on the front side of the cabin 61 and the rear side of the loading platform 62. In the truck 60 (mobile body) shown in Figure 6(c), gas resistance reduction structures 1c are arranged at corners that form the boundaries between the front and side of the truck 60 (mobile body) and at corners that form the boundaries between the back and side of the truck 60 (mobile body), i.e., on the front side of the cabin 61 and the rear side of the loading platform 62. In the passenger car 70 (mobile body) shown in Figures 7(a) and 7(b), gas resistance reduction structures 1c are arranged at the corners that form the boundary between the front and side of the passenger car 70 (mobile body) and at the corners that form the boundary between the back and side of the passenger car 70 (mobile body), i.e., on the front and rear sides of the vehicle body 71.

[0234] 2.Structures The structure in the present disclosure is disposed on at least one of the top surface or side surface of the moving body. The structure may be disposed only on the top surface of the moving body, only on the side surface of the moving body, or on both the top surface and the side surface of the moving body.

[0235] The structures vary depending on the mobile body. When the mobile body is an automobile or a railroad vehicle, tall structures are rarely placed on the sides of the mobile body in order to avoid contact between the mobile bodies or between the mobile body and people or objects, and structures are often placed on the top surface of the mobile body. In the case of a bus, examples of the structures include aerodynamic parts, air conditioning units, and steps. In the case of a truck, examples of the structures include aerodynamic parts such as air deflectors and luggage beds. In the case of a passenger car, examples of the structures include aerodynamic parts, antennas such as dolphin antennas (shark antennas), roof boxes, warning lights, company name signs, and steps. In the case of a train or a Shinkansen, examples of the structures include aerodynamic parts such as pantograph covers and pantograph soundproofing panels, and air conditioning units.

[0236] Among these, the structure is preferably an aerodynamic part. By arranging an air resistance reduction structure on the aerodynamic part, the effect of reducing air resistance can be enhanced. In the case of an automobile, the aerodynamic part is preferably an aerodynamic part that is arranged behind the front of the automobile, and more preferably an aerodynamic part that is arranged at the rear of the automobile. Specifically, examples of aerodynamic parts include a roof spoiler, a rear spoiler, a side spoiler, a rear wing, and a vortex generator.

[0237] 3. Mobile The mobile body in the present disclosure is a mobile body that has a driver's seat and a windshield in front of the driver's seat. Examples of mobile bodies include automobiles such as passenger cars, trucks, and buses; railway vehicles such as trains, bullet trains, and locomotives; aircraft such as passenger planes, helicopters, and air mobility; and ships. Air mobility is what is known as a flying car. The mobile body is preferably a non-streamlined body, specifically a bluff body. This is because, in a bluff body, pressure resistance contributes significantly to gas resistance, and the effects of the present disclosure are particularly pronounced. Preferred examples of mobile bodies that are bluff bodies include trucks, buses, and the like.

[0238] 4. Other points In the present disclosure, gas resistance can be reduced. The gas is not particularly limited. The density of the gas is, for example, 0.08 kg / m 3 More than 10kg / m 3 The following is preferable: Among these, the gas is preferably air.

[0239] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any embodiment that has substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibits similar effects is included within the technical scope of the present disclosure. [Example]

[0240] [Reference example 1] A printing stock (3M's "IJ180 mC-114") with a vinyl chloride resin film was used. A laminate film (Avery Dennison's "DOL1460Z") was also used, which consisted of a vinyl chloride resin film, an adhesive layer, and a release paper, in that order. After peeling the release paper from the laminate film, the laminate film was laminated onto the printing stock. Next, a UV-curable ink (Dainichiseika Chemicals' "Seikabeam HT509") was ejected and cured onto the vinyl chloride resin film of the laminate film using a UV inkjet device, forming a first region with multiple linear convex and concave portions. The first region was formed so that the first and second regions were alternately arranged in a striped pattern, as shown in Figure 1(a). This resulted in the production of a film-like gas drag reduction structure. The size of the film-like gas drag reduction structure was A4 size (210 mm × 297 mm). The width of the first region was 7 mm, the width of the second region was 7 mm, the length of the first region was 210 mm, the height of the convex portions of the first region was 0.02 mm to 2 mm, the width of the convex portions of the first region was 0.02 mm to 2 mm, and the width of the concave portions of the first region was 0.14 mm to 1.4 mm.

[0241] A truck-shaped model was used, measuring 1250 mm in length, 260 mm in width, and 387 mm in height, as shown in Figures 19(a) to 19(c). Figure 19(a) is a top view of the model, Figure 19(b) is a side view of the model, and Figure 19(c) is a rear view of the model. This truck-shaped model is a simple model that is 1 / 10 the size of a 10-ton truck. A film-like gas drag reduction structure was attached to the upper front part of the truck-shaped model. A wind tunnel experiment was conducted under the following conditions, and the air drag coefficient (Cd value) was measured.

[0242] <Wind tunnel test conditions> Outlet dimensions: Rectangular, 1.0m wide and 0.7m high Measurement section length: 1.45m ·Wind speed: 25m / s - Size of film-type gas drag reduction structure: 210mm x 297mm Placement: Front upper part of truck-shaped model · Attachment method: As shown in Figure 20(b), an A4 size film-like gas drag reduction structure 1 was attached to the truck-shaped model, with the front R start point as the tip and facing rearward.

[0243] The Cd value was calculated using the following formula. Cd=D / (ρU 2 S×1 / 2) (In the above formula, D: drag (N), ρ: density (kg / m 3 ), U: Representative speed (m / s), S: Representative area (m 2 ) In this experiment, the drag force D was measured using a load cell with a wire attached to a truck-shaped model. The density ρ was 1.124 kg / m 3 , the representative speed U is the same as the wind speed, and the representative area S is 0.101m 2 It was decided.

[0244] In addition, Comparative Example 1 was a case where no film-like gas resistance reducing structure was attached.

[0245] [Table 1]

[0246] As shown in FIG. 20(b), in a truck-shaped model, the distance along the surface of the truck-shaped model from the reference point E0 at the tip of the truck-shaped model to the tip of the gas drag reduction structure 1 is 120 mm. In this case, when the wind speed is 25 m / s (90 km / h), the boundary layer thickness δ at the position of the tip of the gas drag reduction structure 1 is 3.9 mm. As shown in Table 1, when the wind speed is 25 m / s (90 km / h), when the height of the convex portions of the concave-convex structure in the first region is 2 mm, the Cd value is higher than when a film-like gas drag reduction structure is not attached to the model. This suggests that it is desirable to set the height of the convex portions of the concave-convex structure in the first region based on the boundary layer thickness at the position of the gas drag reduction structure.

[0247] [Reference example 2] A design was printed on a printing stock (MPI1105) manufactured by Avery Dennison, and a laminate film (DOL1460) manufactured by Avery Dennison was laminated on top of it. Specifically, first, a printing stock ("MPI1105" manufactured by Avery Dennison) having a vinyl chloride resin film, an adhesive layer, and a release paper in this order was used, and a design was printed on the vinyl chloride resin film of the printing stock to form a printed layer. Next, a laminate film ("DOL1460" manufactured by Avery Dennison) having a vinyl chloride resin film, an adhesive layer, and a release paper in this order was used, and after peeling the release paper from the laminate film, the laminate film was laminated on the printed layer.

[0248] Next, a UV-curable ink (Seikabeam HT509, manufactured by Dainichiseika Chemicals Co., Ltd.) was ejected and cured using a UV inkjet device onto the laminate film, i.e., onto the vinyl chloride resin film of the laminate film, to form a first region having multiple linear convex and concave portions. The first region was formed so that the first and second regions were alternately arranged in a striped pattern, as shown in Figure 1(a). This resulted in the production of a film-like gas drag reduction structure. The size of the film-like gas drag reduction structure was A4 size (210 mm x 297 mm). Details of the gas drag reduction structure are shown in Table 2.

[0249] [Rating 2] A truck-shaped model was used as in Evaluation 1 above. A film-like gas drag reduction structure was attached to the front sides and front upper part of the truck-shaped model. A wind tunnel experiment was conducted under the following conditions to measure the air resistance coefficient (Cd value). The Cd value was determined in the same way as in Evaluation 1 above.

[0250] <Wind tunnel test conditions> Outlet dimensions: Rectangular, 1.0m wide and 0.7m high Measurement section length: 1.45m ·Wind speed: 25m / s - Size of film-type gas drag reduction structure: 210mm x 297mm Placement: Front side and front top of truck model · Attachment method: As shown in Figures 20(a) and 20(b), a film-like gas drag reduction structure was attached to the truck-shaped model, starting from the front R start point and pointing rearward.

[0251] In addition, Comparative Example 2 was a case where no wrapping film was attached.

[0252] [Table 2]

[0253] As shown in FIG. 20(b), on the top surface of the truck-shaped model, the distance along the surface of the truck-shaped model from the reference point E0 at the tip of the truck-shaped model to the tip of the gas drag reduction structure 1 is 120 mm. In this case, when the wind speed is 25 m / s (90 km / h), the boundary layer thickness δ at the position of the tip of the gas drag reduction structure 1 is 3.9 mm. Also, as shown in FIG. 20(a), on the side surface of the truck-shaped model, the distance along the surface of the truck-shaped model from the reference point E0 at the tip of the truck-shaped model to the tip of the gas drag reduction structure 1 is 105 mm. In this case, when the wind speed is 25 m / s (90 km / h), the boundary layer thickness δ at the position of the tip of the gas drag reduction structure 1 is 3.5 mm. As shown in Table 2, at a wind speed of 25 m / s (90 km / h), when the width of the first region and the width of the second region in the direction intersecting the direction of travel of the moving object were 100 mm, the Cd value was as high as when no film-like gas drag reduction structure was attached to the model. This suggests that it is desirable to set the width of the first region and the width of the second region in the direction intersecting the direction of travel of the moving object based on the boundary layer thickness at the position of the gas drag reduction structure.

[0254] The present disclosure provides the following inventions. [1] A moving body having a gas drag reduction structure on its surface, the gas drag reduction structure has a first region having an uneven structure and a second region adjacent to the first region, the first region and the second region extending in a band shape in the traveling direction of the moving body, a structure is disposed on at least one of an upper surface and a side surface of the moving body; the gas drag reduction structure is disposed on the structure, A moving body, wherein in the gas resistance reduction structure disposed on the structure, the height of the convex portions of the concave-convex structure in the first region, and the width of the first region and the width of the second region in a direction intersecting the direction of travel of the moving body are set based on the boundary layer thickness at the position of the gas resistance reduction structure. [2] The moving body according to [1], wherein in the gas resistance reduction structure, the first regions and the second regions are alternately arranged in a direction intersecting the traveling direction of the moving body. [3] A moving body as described in [1] or [2], wherein in the gas drag reduction structure disposed on the structure, the height of the convex portions of the uneven structure in the first region is 0.01% to 50% of the boundary layer thickness at the position of the gas drag reduction structure, and the width of the first region and the width of the second region in a direction intersecting the direction of travel of the moving body are 0.5 to 3 times the boundary layer thickness at the position of the gas drag reduction structure. [4] A moving body described in any one of [1] to [3], wherein the gas drag reduction structure is disposed in at least one selected from the group consisting of a corner at the boundary between the front and side surfaces of the moving body, a corner at the boundary between the front and top surfaces of the moving body, a corner at the boundary between the back surface and side surfaces of the moving body, and a corner at the boundary between the back surface and top surfaces of the moving body. [Explanation of symbols]

[0255] 1. Gas drag reduction structure 2 … 1st area 3 … Second area 10 … uneven structure 11... Convex part 12 ... recess 20 … structure 50... Bus (mobile) 60... Truck (mobile) 70... Passenger car (mobile) D1: Direction of travel of the moving object D2: Direction that intersects with the direction of travel of the moving object

Claims

1. A moving body having a gas drag reduction structure on a surface thereof, the gas drag reduction structure has a first region having a concave-convex structure and a second region adjacent to the first region, the first region and the second region extending in a band shape in a traveling direction of the moving body, a structure is disposed on at least one of an upper surface or a side surface of the moving body; the gas drag reduction structure is disposed on the structure, a gas resistance reduction structure disposed on the structure, wherein the height of the convex portions of the uneven structure in the first region, and the width of the first region and the width of the second region in a direction intersecting the direction of travel of the moving body are set based on the boundary layer thickness at the position of the gas resistance reduction structure.

2. The moving body according to claim 1 , wherein in the gas resistance reduction structure, the first regions and the second regions are alternately arranged in a direction intersecting a traveling direction of the moving body.

3. 2. The moving body according to claim 1, wherein in the gas drag reduction structure disposed on the structure, the height of the convex portions of the uneven structure in the first region is 0.01% to 50% of the boundary layer thickness at the position of the gas drag reduction structure, and the width of the first region and the width of the second region in a direction intersecting the direction of travel of the moving body are 0.5 to 3 times the boundary layer thickness at the position of the gas drag reduction structure.

4. 3. The moving body according to claim 1, wherein the gas drag reduction structure is disposed in at least one selected from the group consisting of a corner that is a boundary between a front surface and a side surface of the moving body, a corner that is a boundary between the front surface and a top surface of the moving body, a corner that is a boundary between a back surface and a side surface of the moving body, and a corner that is a boundary between the back surface and a top surface of the moving body.

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