Flow control device

Abstract

To provide a flow control device capable of suppressing the peel-off itself of a flow and reducing the effects of a vortex (an eddy degree) occurring on the rear side.SOLUTION: A flow control device 20 includes a plate-like member 21 attached to a mounted body 1 for suppressing the peel-off of the flow of fluid from a mounted body surface 12 of the mounted body 1 and weakening the eddy degree to form an inward flow path Ra between the mounted body surface 12 and itself. At the downstream side end of the plate-like member 21, an irregular part is formed having crest parts 22 and trough parts 23. The flow of the fluid from the upstream is separated into inward flow paths Ra, Rb and outward flow paths Sa, Sb by the plate-like member 21 so that the eddy degree on the downstream of the plate-like member 21 is weakened by the irregular part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a flow control device that suppresses separation of a fluid flow from a surface of an object and reduces vorticity. [Background technology]

[0002] In land transport vehicles such as automobiles (passenger cars, trucks, buses, etc.) and trains, corners or edges with small R are inevitably formed on the body surface due to restrictions on internal space. In particular, at rear corners or edges with small R, the fluid flow separates from the vehicle body surface, and a strong vorticity area occurs behind the area, which leads to increased air resistance, worsening fuel efficiency (electricity efficiency), increased greenhouse gas emissions, worsening driving stability, and worsening ride comfort. In addition, the vorticity flows out rearward while fluctuating with time, which can also cause aerodynamic noise. Furthermore, in the natural environment in which land transport vehicles are actually operated, the strength and direction of the relative wind are not constant from time to time, and relative wind may flow into the vehicle from the side. When such a crosswind is received, separation of the fluid flow also occurs in the side part, leading to increased air resistance, increased lateral force, worsening fuel efficiency (electricity efficiency), increased greenhouse gas emissions, and worsening driving stability. For example, the rear spoiler of a vehicle disclosed in Patent Document 1 has a rear edge on which a plurality of protrusions protruding rearward are provided, separated from one another by recesses provided at predetermined intervals in the vehicle width direction. The upper surfaces of the protrusions extend on the same plane as the rear end side of the upper surface of the rear spoiler as part of the upper surface of the rear spoiler, and the radius of curvature of a first edge forming the front end of the recesses on the upper surface of the rear spoiler, on a cross section parallel to a plane perpendicular to the vehicle width direction, is made larger than the radius of curvature of a second edge forming the rear end of the upper surface of the protrusions, on the cross section. According to Patent Document 1, the air flowing onto the rear spoiler is divided into a first airflow that passes over the first edge connected to the recess, and a second airflow that passes over the protrusion and then over the second edge. The first airflow and the second airflow form a vertical vortex behind the vehicle because they have different outflow angles. The vertical vortex draws in part of the high-speed airflow at the upper part downward, suppressing the strength of the horizontal vortex that occurs behind the vehicle. As a result, the pressure below the rear spoiler at the rear of the vehicle increases, reducing air resistance. Patent Documents 2 and 3 disclose impellers in which serrations that generate longitudinal vortices are provided at the leading and trailing ends of the blades, causing an imbalance between the longitudinal vortices and making the longitudinal vortices finer, thereby making it possible to sufficiently reduce the correlation area of ​​the pressure fluctuations of the airflow that separates from the blade surface, thereby achieving a sufficient noise reduction effect. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-81487 A [Patent Document 2] JP 2013-249762 A [Patent Document 3] JP 2017-110555 A Summary of the Invention [Problem to be solved by the invention]

[0004] As disclosed in Patent Documents 1 to 3, the conventional techniques are primarily aimed at reducing vortices (vorticity) generated by flow separation.

[0005] An object of the present invention is to provide a flow control device that can suppress flow separation itself and reduce the effect of vortices (vorticity) generated behind it. [Means for solving the problem]

[0006] The flow control device 20 of the present invention described in claim 1 is attached to an object to be attached 1, suppresses separation of a fluid flow from an object to be attached 1 surface 12 of the object to be attached 1, and weakens vorticity, and has a plate-like member 21 that forms inner flow paths Ra, Rb between the object to be attached 1 surface 12, and a bumpy portion having peaks 22 and valleys 23 is formed at the downstream end of the plate-like member 21, and the plate-like member 21 separates the fluid flow from upstream into the inner flow paths Ra, Rb and outer flow paths Sa, Sb, and the bumpy portion weakens the vorticity downstream of the plate-like member 21. The present invention according to a second aspect is characterized in that in the flow control device 20 according to the first aspect, the inner flow paths Ra, Rb have an upstream flow path cross-sectional area greater than or equal to the downstream flow path cross-sectional area. The present invention according to a third aspect is characterized in that, in the flow control device 20 according to the first aspect, the fluid Fin in the inner flow passages Ra, Rb has a higher flow velocity than the fluid Fout in the outer flow passages Sa, Sb. The present invention described in claim 4 is characterized in that, in the flow control device 20 described in claim 1, the thicknesses of the peak portions 22 and the valley portions 23 are gradually reduced toward the downstream end, and the peak portions are curved from the valley portions toward the inward flow path toward the downstream end. The present invention described in claim 5 is characterized in that, in the flow control device 20 described in claim 1, the substrate surface 12 has adjacent first substrate surface 12a and second substrate surface 12b, and when a first normal A of the first substrate surface 12a and a second normal B of the second substrate surface 12b are different, the plate-shaped member 21 includes a first plate-shaped member 21a that forms a first inner flow path Ra between the first substrate surface 12a and the second substrate surface 12b, and a second plate-shaped member 21b that forms a second inner flow path Rb between the second substrate surface 12b, and an end of the first plate-shaped member 21a and an end of the second plate-shaped member 21b are connected. The present invention according to a sixth aspect is characterized in that in the flow control device 20 according to any one of the first to fifth aspects, the object to be attached 1 is a vehicle. Effect of the Invention

[0007] According to the present invention, the inner flow path suppresses the separation of the fluid flow from the surface of the object to which the device is attached, and the uneven portion reduces the vortex generated downstream of the plate-like member due to the speed difference between the fluid flow in the inner flow path and the fluid flow in the outer flow path, thereby weakening the vorticity, thereby reducing the air resistance and aerodynamic noise on the object to which the device is attached, and improving the fuel efficiency, driving stability, and ride comfort of the land transport equipment to which the device is attached. Furthermore, the device weakens the vorticity behind the land transport equipment to which the device is attached, preventing the stirring up of dust, exhaust gas, etc., and suppressing dirt on the vehicle body, etc. [Brief description of the drawings]

[0008] [Figure 1] A photograph showing an object to which a flow control device according to an embodiment of the present invention is to be attached. [Diagram 2] FIG. 1 shows the flow control device attached to the license plate mounting portion. [Diagram 3] FIG. 2 shows the flow control device. [Figure 4] FIG. 2 shows a second plate-shaped member [Diagram 5] FIG. 1 shows a flow of fluid through a plate-like member. [Figure 6] CFD analysis showing isosurfaces of turbulent energy [Figure 7] CFD analysis diagram showing cross-sectional vorticity distribution [Figure 8] Graph showing the effect of reducing air resistance [Figure 9] FIG. 1 is a diagram showing the mounting position of a flow control device according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A flow control device according to a first embodiment of the present invention has a plate-like member that forms an inner flow path between itself and the surface of an object to be attached, and a concave-convex portion having peaks and valleys is formed at the downstream end of the plate-like member, the plate-like member separates the flow of fluid from upstream into an inner flow path and an outer flow path, and the concave-convex portion weakens the vorticity downstream of the plate-like member. According to this embodiment, the inner flow path suppresses separation of the fluid flow from the surface of the object to be attached, and the concave-convex portion reduces vortices generated downstream of the plate-like member due to the speed difference between the flow of fluid in the inner flow path and the flow of fluid in the outer flow path, thereby weakening the vorticity, thereby reducing air resistance and aerodynamic noise on the object to be attached.

[0010] In the second embodiment of the present invention, in the flow control device according to the first embodiment, the inner flow passage has an upstream flow passage cross-sectional area equal to or larger than the downstream flow passage cross-sectional area, so that a sufficient amount of fluid can be made to flow in the inner flow passage.

[0011] A third embodiment of the present invention is a flow control device according to the first embodiment, in which the fluid in the inner flow path flows faster than the fluid in the outer flow path. According to this embodiment, the pressure in the inner flow path can be made lower than that in the outer flow path, and the flow of the fluid in the outer flow path can be entrained in the flow of the fluid in the inner flow path.

[0012] In the fourth embodiment of the present invention, in the flow control device according to the first embodiment, the thickness of the peaks and valleys is gradually reduced toward the downstream end, and the peaks are curved from the valleys toward the inner flow path toward the downstream end. According to this embodiment, the generation and growth of vorticity generated at the downstream end can be suppressed.

[0013] A fifth embodiment of the present invention is a flow control device according to the first embodiment, in which the surface of the substrate includes a first substrate surface and a second substrate surface adjacent to each other, and when the first normal to the first substrate surface and the second normal to the second substrate surface are different, the plate-like members include a first plate-like member forming a first inner flow path between the first substrate surface and the second substrate surface, and a second plate-like member forming a second inner flow path between the second substrate surface and the first substrate surface, and an end of the first plate-like member and an end of the second plate-like member are connected to each other. According to this embodiment, the generation and growth of vorticity occurring between the first substrate surface and the second substrate surface can be suppressed.

[0014] The sixth embodiment of the present invention is a flow control device according to any one of the first to fifth embodiments, in which the object to be attached is a vehicle. According to this embodiment, it is possible to reduce air resistance and aerodynamic noise, as well as improve fuel efficiency, driving stability, and ride comfort. Furthermore, it is also effective in preventing dust, exhaust gas, and the like from being stirred up, and in preventing dirt on the vehicle body, etc. EXAMPLES

[0015] A flow control device according to one embodiment of the present invention will now be described. FIG. 1 is a photograph showing an object to which a flow control device in one embodiment of the present invention is attached, where FIG. 1(a) is a photograph taken from the rear of the object, and FIG. 1(b) is an enlarged photograph of the main part of FIG. 1(a). The object 1 shown in FIG. 1 is a solar car, and the flow control device 20 is attached to the number plate mounting portion 10 of the solar car. The license plate mounting section 10 is composed of a license plate mounting surface 11 and a mounting surface 12 of an object extending in the direction in which the solar car travels. In this embodiment, the surface 12 of the object to be attached is composed of a pair of first surfaces 12a forming side surfaces and a second surface 12b forming a bottom surface. The first surface 12a and the second surface 12b of the object to be attached are adjacent to each other. The flow control device 20 is attached to the substrate 1 and suppresses separation of the fluid flow from the substrate surface 12 of the substrate 1 and reduces vorticity.

[0016] Figure 2 shows the flow control device attached to the license plate mounting section, where Figure 2(a) is a perspective view from the rear of the body to which it is attached, Figure 2(b) is a top view of the part shown in Figure 2(a), Figure 2(c) is a side view of the part shown in Figure 2(a), and Figure 2(d) is a photograph taken from below and in front of the part shown in Figure 2(a). As shown in FIG. 2, the plate-like member 21 constituting the flow control device 20 has a first plate-like member 21a that forms a first inner flow path Ra between itself and the first substrate surface 12a, and a second plate-like member 21b that forms a second inner flow path Rb between itself and the second substrate surface 12b. The end of the first plate-shaped member 21a and the end of the second plate-shaped member 21b are connected. Therefore, it is possible to suppress the generation and growth of vorticity at the corner portion between the first and second object surfaces 12a and 12b. It is preferable that the connection portion between the first and second plate-shaped members 21a and 21b is a connection portion to the license plate mounting portion 10 of the plate-shaped member 21. As shown in FIG. 2(b), a first normal A to the first object surface 12a is different from a second normal B to the second object surface 12b forming the bottom surface.

[0017] Fig. 3 shows the flow control device, Fig. 3(a) is a perspective view from above the front, Fig. 3(b) is a perspective view from below the front, Fig. 4 shows the second plate-like member, Fig. 4(a) is a top view of the second plate-like member, Fig. 4(b) is an XX end view of Fig. 4(a), and Fig. 4(c) is a YY end view of Fig. 4(a). Note that Fig. 4 shows the second plate-like member 21b, but the following explanation is similar to that of the first plate-like member 21a, so it will be explained as the plate-like member 21. The flow control device 20 has a plate-like member 21 having a downstream end formed with an uneven portion having peaks 22 and valleys 23 . As shown in FIG. 4, the ridges 22 of the plate-like member 21 have curved surfaces formed on their outer surfaces to guide the fluid Fout flowing through the outer flow paths Sa, Sb toward the fluid Fin flowing through the inner flow paths Ra, Rb. Further, in the valley portion 23 of the plate-like member 21, a curved surface is formed on the inner surface of the valley portion 23 for guiding the fluid Fin flowing through the inner flow passages Ra, Rb in the direction of the fluid Fout flowing through the outer flow passages Sa, Sb. The thickness of the peaks 22 and the valleys 23 is gradually reduced toward the downstream end. By gradually reducing the thickness of the peaks 22 and the valleys 23 toward the downstream end in this manner, the generation and growth of vorticity occurring at the downstream end can be suppressed. In this embodiment, the peaks 22 and the valleys 23 are arranged with a regularity, but it is not necessary that the peaks 22 and the valleys 23 of the same shape are arranged with a regularity. The peaks 22 may each have a different size or end face shape, and the valleys 23 may also each have a different size or end face shape.

[0018] FIG. 5 is a diagram showing the flow of a fluid through a plate-like member, where FIG. 5(a) is an enlarged view of a main part of FIG. 2(b), and FIG. 5(b) is an enlarged view of a main part of FIG. 2(c). As shown in FIG. 5(a), the first plate-shaped member 21a separates the fluid from upstream into a fluid Fin flowing through the first inner flow passage Ra and a fluid Fout flowing through the outer flow passage Sb. The first inner flow passage Ra suppresses separation of the fluid flow from the first object surface 12a of the object 1. As shown in FIG. 5(b), the second plate-shaped member 21b separates the fluid from the upstream into a fluid Fin flowing through the second inner flow passage Rb and a fluid Fout flowing through the outer flow passage Sa. The second inner flow passage Rb suppresses separation of the fluid flow from the second object surface 12b of the object 1. In this way, the plate-like member 21 separates the fluid flow from upstream into inner flow paths Ra, Rb and outer flow paths Sa, Sb, and the inner flow paths Ra, Rb can suppress separation of the fluid flow from the surface 12 of the object to be attached 1.

[0019] Furthermore, the uneven portion having peaks 22 and valleys 23 shown in FIG. 4 can reduce vortices that are generated downstream of the first plate-shaped member 21a and the second plate-shaped member 21b due to the speed difference between the flow of the fluid Fin in the inner flow paths Ra, Rb and the flow of the fluid Fout in the outer flow paths Sa, Sb, thereby weakening the vorticity. Therefore, by attaching the flow control device 20 to the attachment object 1, the air resistance and aerodynamic noise at the attachment object 1 can be reduced.

[0020] In addition, as shown in this embodiment, by using a vehicle as the mounting body 1, it is possible to improve fuel efficiency, driving stability, and ride comfort. Here, the vehicle refers to automobiles such as passenger cars, trucks, buses, and motorcycles, and also includes vehicles guided by rails, rails, or cables.

[0021] In addition, by making the upstream flow passage cross-sectional area of ​​the inner flow passages Ra, Rb equal to or larger than the downstream flow passage cross-sectional area, a sufficient amount of fluid can flow in the inner flow passages Ra, Rb. In addition, it is preferable that the fluid in the inner flow passages Ra, Rb has a higher flow rate than the fluid in the outer flow passages Sa, Sb. By making the flow rate of the fluid in the inner flow passages Ra, Rb faster than that of the fluid in the outer flow passages Sa, Sb, the pressure in the inner flow passages Ra, Rb can be made lower than that of the outer flow passages Sa, Sb, and the flow of the fluid Fout in the outer flow passages Sa, Sb can be entrained in the flow of the fluid Fin in the inner flow passages Ra, Rb.

[0022] FIG. 6 is a CFD analysis diagram showing isosurfaces of turbulent energy, where FIG. 6(a) shows the case when no flow control device is installed, FIG. 6(b) shows the case when a flow control device that does not have an uneven portion formed on the downstream end of the plate-like member is installed, and FIG. 6(c) shows the case when the flow control device according to this embodiment is installed. As shown in Fig. 6(a), when the flow control device 20 is not installed, the flow separates from the surface 12 of the object to be mounted at the license plate mounting portion 10, and vortices are generated at the isosurface of the turbulent energy. Therefore, as the air resistance increases, the fuel efficiency (electricity efficiency) worsens. As shown in FIG. 6(b), when a flow control device 20 in which no unevenness is formed on the downstream end of the plate-like member 21 is attached, it is found that separation can be suppressed. Furthermore, as shown in FIG. 6(c), when the flow control device 20 of this embodiment, in which an uneven portion is formed on the downstream end of the plate-like member 21, is attached, the vortex (vorticity) behind the license plate mounting portion 10 is further weakened compared to FIG. 6(b), and the effect of the flow control device 20 of this embodiment can be confirmed.

[0023] FIG. 7 is a CFD analysis diagram showing the cross-sectional vorticity distribution, where FIG. 7(a) shows the case when no flow control device is installed, FIG. 7(b) shows the case when a flow control device that does not have an uneven portion formed on the downstream end of the plate-like member is installed, and FIG. 7(c) shows the case when the flow control device according to this embodiment is installed. Compared with Figure 7(a), it can be seen that separation is suppressed when a flow control device 20 that does not have an uneven portion formed on the downstream end of the plate-like member 21 is attached, as shown in Figure 7(b). Furthermore, as shown in Figure 7(c), when the flow control device 20 of this embodiment, in which an uneven portion is formed on the downstream end of the plate-like member 21, is attached, the vortex (vorticity) behind the license plate mounting portion 10 is further weakened compared to Figure 7(b), and the effect of the flow control device 20 of this embodiment can be confirmed.

[0024] FIG. 8 is a graph showing the air resistance reduction effect. FIG. 8 shows the air resistance reduction rate when a flow control device 20 that does not have an uneven portion formed on the downstream end of the plate-like member 21 is installed, and when a flow control device 20 according to this embodiment is installed, with the case where the flow control device 20 is not installed as a reference. When a flow control device 20 that does not have an uneven portion formed on the downstream end of the plate-like member 21 is installed, a reduction effect of approximately 1.8% is achieved, and when the flow control device 20 of this embodiment is installed, a reduction effect of approximately 4.5% is confirmed as a result of the shear layer being suppressed.

[0025] FIG. 9 is a diagram showing the mounting position of the flow control device according to this embodiment. In FIG. 9, the object 1 is a land transport vehicle. The object 1 has a loading platform 1a and a cabin 1b. The flow control device 20 can be attached to both side regions a at the rear end of the loading platform 1a, the upper end region b at the rear end of the loading platform 1a, and the lower end region c at the rear end of the loading platform 1a, and can be further effective by being attached to both side regions d on the upper surface of the loading platform 1a or both side regions e on the lower surface of the loading platform 1a. In addition, the flow control device 20 can be attached to the rear end side regions f of the cabin 1b and the rear end upper end region g of the cabin 1b, and can be more effective by being attached to the upper surface side regions h of the cabin 1b and the front end side regions i of the cabin 1b. In this way, when the object to be attached 1 is a land transportation equipment, a plate-like member 21 having a curved shape is installed at a corner or an end with a small radius on the body surface which becomes the surface 12 of the object to be attached, with a gap between the plate-like member 21 and the surface 12 of the object to be attached, and further, by cutting off the rear end of the plate-like member 21 in a wavy shape, peeling can be suppressed and the shear layer and vorticity formed behind the plate-like member 21 can be reduced, thereby reducing the air resistance of the land transportation equipment, improving fuel efficiency (electricity efficiency), reducing greenhouse gas emissions, and further improving fuel efficiency (actual fuel efficiency) under actual driving conditions (under actual wind conditions) of the land transportation equipment and reducing greenhouse gas emissions. That is, in the present invention, the plate-like member 21 having a curved shape is installed in a manner that leaves a gap at the corners or the end with a small radius on the body surface of the land transport equipment, thereby suppressing the separation of the flow at the corners or the end with a small radius, and further, by cutting off the rear end of the plate-like member 21 in a wavy shape, the direction of the axis of the vortex (vorticity) generated at the rear end of the plate-like member is changed to a vertical vortex, which promotes turbulent mixing and reduces the shear layer and vorticity generated behind the plate-like member. Furthermore, it is possible to suppress aerodynamic noise generated by unsteady changes in vorticity. Furthermore, when the land transport equipment is subjected to a crosswind, separation of the flow also occurs at the side part, which leads to an increase in air resistance, an increase in lateral force, a deterioration in fuel efficiency (electricity efficiency), an increase in greenhouse gas emissions, a deterioration in driving stability, and a deterioration in ride comfort. Therefore, by providing the plate-like member 21 of the present invention at the side part, it is possible to improve the aerodynamic characteristics under crosswind inflow conditions and improve actual fuel efficiency.

[0026] In this way, the present invention is a technology that can greatly contribute to reducing air resistance, improving fuel efficiency (electricity cost), and reducing greenhouse gas emissions for land transport equipment such as automobiles (passenger cars, trucks, buses, etc.) and trains, as well as improving fuel efficiency (actual fuel efficiency) under actual driving conditions (under actual wind conditions) and reducing greenhouse gas emissions for land transport equipment, and can greatly contribute to the development of land transport equipment, which requires rapid response toward achieving carbon neutrality. Furthermore, it can simultaneously reduce aerodynamic noise. [Industrial Applicability]

[0027] According to the present invention, it is possible to reduce air resistance and aerodynamic noise on an object to which the device is attached. [Explanation of symbols]

[0028] 1 Attached object 1a Cargo platform 1b Cabin 10 Number plate attachment part 11 Number plate mounting surface 12 Surface of the object to be attached 12a First attached object surface 12b Second attached object surface 20 Flow Control Device 21 Plate-shaped member 21a First plate-shaped member 21b Second plate-shaped member 22 Yamabe 23 Valley a) Posterior both sides b Upper rear end area c Posterior lower end area d. Upper side both sides e. Both sides of the lower surface f. Posterior both sides g Upper rear end area h Upper side both sides i. Front end both sides A First normal B 2nd normal Fin fluid Fout fluid Ra Inner flow passage (first inner flow passage) Rb Inner flow passage (second inner flow passage) Sa, Sb outer flow path

Claims

1. A flow control device that is attached to an object to be attached and that suppresses separation of a fluid flow from a surface of the object to be attached and reduces vorticity, a plate-like member that forms an inner flow path between the plate-like member and the surface of the object to be attached; A projection and recess having peaks and valleys is formed on the downstream end of the plate-like member, The plate-like member separates the flow of the fluid from the upstream into the inner flow passage and the outer flow passage, The uneven portion weakens the vorticity downstream of the plate-like member. A flow control device comprising:

2. The inner flow passage has an upstream flow passage cross-sectional area equal to or larger than a downstream flow passage cross-sectional area.

2. The flow control device of claim 1.

3. The fluid in the inner flow passage flows faster than the fluid in the outer flow passage.

2. The flow control device of claim 1.

4. 2. The flow control device according to claim 1, wherein the peaks and valleys are gradually thinner toward the downstream end and curved toward the inner flow passage toward the downstream end.

5. the substrate surface comprises a first substrate surface and a second substrate surface adjacent to each other; When a first normal to the surface of the first object to be attached and a second normal to the surface of the second object to be attached are different, As the plate-like member, a first plate-like member that forms a first inner flow passage between itself and a surface of the first object to be attached; a second plate-like member that forms a second inner flow passage between itself and a surface of the second object; having An end of the first plate-like member and an end of the second plate-like member are connected to each other.

2. The flow control device of claim 1.

6. The object to be mounted is a vehicle. A flow control device according to any one of claims 1 to 5.

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