Contra-rotating type full-revolving propeller twisted pod supporting column and design method thereof

Abstract

The invention relates to a twisted pod supporting column of a contra-rotating full-revolving propeller and a design method thereof, and provides a twisted pod supporting column structure and a design method aiming at the design defects of a supporting column body in an existing contra-rotating full-revolving propeller. According to the structure, the supporting column body is divided into the first pre-rotation section and the second pre-rotation section which are both in a distortion design, the distortion angle of the first pre-rotation section is unchanged or monotonically decreased, the distortion angle of the second pre-rotation section is monotonically decreased, and the maximum distortion angles do not exceed 5 degrees and 3 degrees respectively. In the aspect of the design method, main design parameters and rotation angle distribution are determined, a profile sketch is drawn, a multi-section curved surface model is established and stitched to form a solid model, and design is completed through numerical evaluation and parameter adjustment. By means of the design, the supporting column body generates the circumferential flowing speed opposite to the rotating direction of the rear propeller so as to improve the rear propeller efficiency, reduce the supporting column shape resistance and improve the overall hydrodynamic efficiency of the propeller unit.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of propeller, in particular to a twisted pod strut of contra-rotating full-revolving propeller and a design method thereof. BACKGROUND

[0002] Full-revolving propeller is a kind of propelling system which can provide vector propulsion in horizontal plane, and it realizes vector propulsion in any direction in horizontal plane by rotating the whole propelling unit around the vertical rotation axis.

[0003] The installation position of full-revolving propeller is no longer limited by shafting as traditional propeller, and it is usually installed below the stern of the ship, so the inflow condition is more uniform than traditional propeller, which can improve the performance of cavitation, vibration and noise of propeller to some extent. At the same time, it can rotate 360 degrees to realize vector propulsion in horizontal plane, and it is widely used in ships with high requirements for maneuvering, such as ocean engineering ships. Full-revolving propeller includes casing and strut, transmission device, shafting and propeller, among which transmission device and shafting are the main force transmission components, and propeller and casing and strut directly interact with water, which are the key components of water power.

[0004] The strut body is the connecting component of propeller and ship body, and its size is usually large due to the limitation of structural strength and internal components. The strut section is usually axisymmetric elliptical or symmetric airfoil section with lower resistance, and the water dynamic interaction between strut and propeller is not considered. The rotational directions of front and rear propellers of contra-rotating full-revolving propeller are opposite, and the circumferential velocity component in the wake field of front propeller increases the attack angle of rear propeller, which is beneficial to improve the water dynamic efficiency of rear propeller. Since contra-rotating transmission device is arranged in the casing, the axial distance between front and rear propellers is usually far, which weakens the pre-whirling effect of front propeller on rear propeller; at the same time, since rear propeller works in the flow field through the strut, the pre-whirling effect of front propeller on the flow field of rear propeller is further weakened, and the existing symmetric form of strut body does not have beneficial effect on the water dynamic efficiency of full-revolving propeller unit.

[0005] Therefore, we propose a twisted pod strut of contra-rotating full-revolving propeller and a design method thereof. SUMMARY

[0006] Therefore, it is necessary to provide a twisted pod strut of contra-rotating full-revolving propeller and a design method thereof in view of the technical problem that the existing symmetric form of strut body in contra-rotating full-revolving propeller does not consider the water dynamic interaction with propeller, which leads to limited improvement of water dynamic efficiency of propeller unit, so that the twisted pod strut of contra-rotating full-revolving propeller can effectively improve the water dynamic efficiency of rear propeller, reduce the shape resistance of strut, and further improve the overall water dynamic efficiency of contra-rotating full-revolving propeller unit.

[0007] The first aspect of the present application provides a twisted nacelle strut for a contra-rotating Z-propeller, which is used to connect a ship body and a propeller, and comprises a strut body connected to the ship body and extending outwardly, a tip connected to the ship body, and a root at an end away from the ship body, a contra-rotating propeller connected to the root of the strut body, and coaxial front and rear propellers arranged on the contra-rotating propeller. The rear propeller disc surface is divided into a first pre-whirl section and a second pre-whirl section by an axial projection line of the rear propeller disc surface on the strut body. The first pre-whirl section and the second pre-whirl section are twisted in the same direction, and the twist direction of the pre-whirl section viewed from the tip to the root is the same as the rotation direction of the rear propeller viewed from the rear propeller to the front propeller. This design makes the strut body generate a circumferential flow velocity opposite to the rotation direction of the rear propeller of the contra-rotating Z-propeller, so as to improve the hydrodynamic efficiency of the rear propeller, and reduce the form drag of the near-tip region of the strut body, thereby improving the hydrodynamic efficiency of the contra-rotating Z-propeller unit.

[0008] In other embodiments, the cross-sectional shape of the strut body is asymmetric, the first pre-whirl section is a section from the root of the strut body to the dividing line, and the second pre-whirl section is a section from the dividing line to the tip of the strut body. The design of the asymmetric cross-section helps to better adapt to the flow field, optimize the hydrodynamic performance, and further improve the efficiency of the propeller unit.

[0009] In other embodiments, the twist angle of each part in the first pre-whirl section is constant or monotonically decreases from the root of the strut body to the dividing line, and the twist angle in the second pre-whirl section monotonically decreases from the dividing line to the tip. The larger twist angle of the first pre-whirl section increases the inflow attack angle of the rear propeller, which is beneficial to improving the hydrodynamic efficiency of the rear propeller. The smaller twist angle of the second pre-whirl section makes the nose-tail line of the strut body cross-sectional profile approach the flow field in front of it, thereby reducing the form drag of the strut body.

[0010] In other embodiments, the maximum twist angle in the first pre-whirl section is not more than 5°, and the maximum twist angle in the second pre-whirl section is not more than 3°. Such angle limitation can not only ensure the effective pre-whirl effect, but also avoid the adverse effects caused by too large angle, and ensure that the strut body has good pre-whirl and drag reduction performance.

[0011] In other embodiments, the contra-rotating propeller comprises a casing connected to the strut body, and coaxial front and rear propellers arranged on both sides of the casing, and the diameter of the rear propeller is smaller than that of the front propeller. This design helps to optimize the overall performance of the propeller, makes the cooperation of the front and rear propellers more reasonable, and improves the propelling efficiency.

[0012] The second aspect of the present application provides a method for designing a twisted nacelle strut of a contra-rotating ZP propeller, comprising the following steps: Step 1. determining the main design parameters of the strut body and the rotation angle distribution, wherein the rotation angle distribution comprises the twist angle variation law of the first pre-whirl section and the second pre-whirl section; Step 2. drawing the profile sketch of each vertical position on the sketch plane according to the main design parameters and the rotation angle distribution; Step 3. establishing a multi-section curved surface model and stitching to form a solid model; Step 4. merging the model with other components of the propeller to form a hydrodynamic calculation model; Step 5. evaluating the hydrodynamic performance by numerical method; Step 6. adjusting the rotation angle parameters until the design indicators are met. Through systematic steps, the method can accurately design a twisted nacelle strut that meets the requirements of hydrodynamic performance, providing an effective means for the optimization design of contra-rotating ZP propeller.

[0013] In other embodiments, the main design parameters include the height, profile length, maximum width and profile distribution form of the strut body. The determination of these parameters provides a basic framework for the design of the strut body, ensuring that the strut body has appropriate size and shape to meet the requirements of structural strength and hydrodynamic performance.

[0014] In other embodiments, the rotation angle distribution parameters include the rotation angle α1 of the root of the strut body on the corresponding horizontal plane, the rotation angle α0 of the demarcation line part of the strut body on the corresponding horizontal plane, and the rotation angle α2 of the tip of the strut body on the corresponding horizontal plane, and satisfy: α1≥α0≥α2, and α1≤5°, α2≥0°. Such parameter restrictions ensure that the rotation angle is monotonically non-increasing in the first pre-whirl section and monotonically decreasing in the second pre-whirl section, so that the strut body has good pre-whirl and drag reduction performance.

[0015] In other embodiments, the numerical evaluation includes the calculation of the thrust, torque and strut resistance of the propeller; and the adjustment of the rotation angle parameters includes modifying at least one of α1, α0 or α2. Through the calculation and adjustment of these key parameters, the design of the strut body can be accurately optimized, and the hydrodynamic performance of the propeller can be improved.

[0016] In other embodiments, the shape of the intermediate profile is controlled by a guide line when establishing the solid model. The use of guide lines can more accurately control the shape of the strut body, ensuring that it meets the design requirements and improving the accuracy and reliability of the model. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a front view of the present application.

[0018] Figure 2 is a right view of Figure 1 .

[0019] Figure 3A height ratio versus profile rotation angle distribution curve of a strut body in an embodiment of the present application.

[0020] Figure 4 A height ratio versus profile rotation angle distribution curve of a strut body in another embodiment of the present application.

[0021] Figure 5 A flowchart of a design method of a twisted pod strut of a full-rotation propeller in an example of the application.

[0022] Figure 6 A model diagram of a strut body in the related art.

[0023] Figure 7 A model diagram of a strut body in the present application.

[0024] Figure 8 A Figure 6 and Figure 7 A rear propeller hydrodynamic efficiency curve corresponding to the strut body model in

[0025] Figure 9 A Figure 6 and Figure 7 A shell and strut drag coefficient diagram corresponding to the strut body model in

[0026] Figure 10 A Figure 6 and Figure 7 A contra-rotating propeller unit hydrodynamic efficiency diagram corresponding to the strut body model in

[0027] Wherein: 100, strut body; 200, contra-rotating propeller;

[0028] 201, shell; 202, front propeller; 203, rear propeller;

[0029] A0, demarcation line; A1, root; A2, tip; S1, first pre-rotation section; S2, second pre-rotation section.

[0030] O, rear propeller disc surface outer edge axial projection line. DETAILED DESCRIPTION

[0031] The specific embodiments of the present application will be described below with reference to the accompanying drawings.

[0032] Example One

[0033] The application discloses a twisted pod strut for contra-rotating full-revolving propeller, and the strut for the contra-rotating full-revolving propeller designed by the design method of the application is provided with a first pre-whirl section S1 in the rear paddle disc surface projection area, so that the strut body 100 generates a circumferential flow velocity opposite to the rotating direction of the rear paddle 203 of the contra-rotating full-revolving propeller, thereby improving the hydrodynamic efficiency of the rear paddle 203. By introducing the first pre-whirl section S1 in the rear paddle disc surface projection area of the strut body 100, the fluid can generate a pre-whirl velocity opposite to the rotating direction of the rear paddle 203 when passing through the strut body 100, thereby improving the inflow condition of the rear paddle 203 and improving the thrust and efficiency of the rear paddle 203. This is of great significance to the overall performance improvement of the ship propulsion system, especially in occasions requiring high-efficiency propulsion.

[0034] The strut body 100 of the contra-rotating full-revolving propeller is provided with a second pre-whirl section S2 outside the rear paddle disc surface projection area, so as to reduce the form drag of the near tip portion A2 area of the strut body 100, thereby improving the hydrodynamic efficiency of the contra-rotating full-revolving propeller unit. The design of the second pre-whirl section S2 further optimizes the overall hydrodynamic performance of the propeller by reducing the form drag of the near tip portion A2 area of the strut body 100. The reduction of the form drag means that the propeller needs to overcome less resistance during operation, thereby reducing energy loss and improving propulsion efficiency. This has a positive effect on improving the speed and fuel economy of the ship.

[0035] The strut body 100 of the contra-rotating full-revolving propeller of the application is of a three-dimensional twisted shape, which can improve the form drag of the strut body 100 on the basis of improving the hydrodynamic efficiency of the rear paddle 203, thereby improving the hydrodynamic efficiency of the contra-rotating full-revolving propeller unit. The design of the three-dimensional twisted shape comprehensively considers the requirements of fluid dynamics and structural strength, so that the strut body 100 can maintain good hydrodynamic performance in each pre-whirl section. This design not only improves the efficiency of the rear paddle 203, but also optimizes the shape of the strut body 100, reduces the resistance, and thereby improves the performance of the entire propeller unit.

[0036] Specifically, as shown in Figure 1 and Figure 2 The strut body 100 of the twisted pod strut for the contra-rotating full-revolving propeller in the embodiment is used for connecting the contra-rotating propeller 200, and comprises the strut body 100, the strut body 100 is connected to the ship body and extends outward, the strut body 100 is provided with the tip portion A2 connected to the ship body and the root portion A1 away from the ship body, and the contra-rotating propeller 200 is connected to the root portion A1 of the strut body 100; so that the contra-rotating propeller 200 can be stably installed on the ship body, while ensuring the stability and reliability of the propeller during operation. The installation position and mode of the contra-rotating propeller 200 have important influence on the performance of the propeller and the sailing stability of the ship.

[0037] As Figure 1 And Figure 2 As shown in the drawings, the contra-rotating propeller 200 in this embodiment includes a casing 201 connected with the strut body 100, and a front paddle 202 and a rear paddle 203 arranged on both sides of the casing 201 and parallel to each other, wherein the diameter of the rear paddle 203 is smaller than that of the front paddle 202. The difference in the diameters of the front paddle 202 and the rear paddle 203 is designed to absorb the energy loss of the tail flow of the front paddle 202 to a greater extent.

[0038] Wherein, the axial projection line of the outer edge of the rear paddle disc surface on the strut body 100 is set as the demarcation line A0, and here it is assumed that the strut body 100 is vertically assembled on the lower end surface of the ship body in actual use, and the axial projection line of the outer edge of the rear paddle disc surface on the strut body 100 is also the position of "O" in the drawings, and the demarcation line A0 divides the strut body 100 into two regions, wherein the first pre-whirl section S1 is located in the axial projection region of the rear paddle disc surface, and the second pre-whirl section S2 is located outside the axial projection region of the rear paddle disc surface; the demarcation line A0 is set to clearly define the range of the first pre-whirl section S1 and the second pre-whirl section S2, so as to accurately control the flow characteristics of the fluid in different regions. This segmented design enables the strut body 100 to play different roles in different regions, which not only improves the efficiency of the rear paddle 203, but also reduces the form drag of the body 100. Figure 1 Figure 2 The first pre-whirl section S1 and the second pre-whirl section S2 are both twisted and have the same twist direction, and the twist direction of the pre-whirl section from the tip A2 to the root A1 is the same as the rotation direction of the rear paddle 203 from the rear paddle 203 to the front paddle 202, both of which are clockwise rotation or counterclockwise rotation. In actual use, it can generate a circumferential flow velocity opposite to the rotation direction of the rear paddle 203 to improve the efficiency of the rear paddle 203, and reduce the attack angle of the flow field to the strut body 100 to reduce the resistance. This twisted design precisely controls the flow direction of the fluid, so that the fluid can generate a pre-whirl speed opposite to the rotation direction of the rear paddle 203 when passing through the strut body 100, thereby improving the inflow conditions of the rear paddle 203. At the same time, reducing the attack angle of the flow field to the strut body 100 helps to reduce resistance and improve propulsion efficiency. This design has a wide application prospect in ship propulsion systems, especially in situations that require high efficiency propulsion.

[0039] The first pre-whirl section S1 and the second pre-whirl section S2 are both twisted and have the same twist direction, and the twist direction of the pre-whirl section from the tip A2 to the root A1 is the same as the rotation direction of the rear paddle 203 from the rear paddle 203 to the front paddle 202, both of which are clockwise rotation or counterclockwise rotation. In actual use, it can generate a circumferential flow velocity opposite to the rotation direction of the rear paddle 203 to improve the efficiency of the rear paddle 203, and reduce the attack angle of the flow field to the strut body 100 to reduce the resistance. This twisted design precisely controls the flow direction of the fluid, so that the fluid can generate a pre-whirl speed opposite to the rotation direction of the rear paddle 203 when passing through the strut body 100, thereby improving the inflow conditions of the rear paddle 203. At the same time, reducing the attack angle of the flow field to the strut body 100 helps to reduce resistance and improve propulsion efficiency. This design has a wide application prospect in ship propulsion systems, especially in situations that require high efficiency propulsion.

[0040] ​The cross-sectional shape of the strut body 100 is non-axially symmetric, the first pre-whirl section S1 is a section from the root A1 to the demarcation line A0 of the strut body 100, and the second pre-whirl section S2 is a section from the demarcation line A0 to the tip A2 of the strut body 100. The division of the first pre-whirl section S1 and the second pre-whirl section S2 enables the strut body 100 to play different roles in different regions, thereby improving the efficiency of the rear propeller 203 and reducing the shape resistance.

[0041] In this embodiment, the twist angle of each part in the first pre-whirl section S1 is constant or monotonically decreases from the root A1 to the demarcation line A0. The larger twist angle increases the attack angle of the inflow of the rear propeller 203, which is beneficial to improve the hydrodynamic efficiency of the rear propeller 203. The design of the twist angle of the first pre-whirl section S1 precisely controls the pre-whirl speed of the fluid, thereby increasing the attack angle of the inflow of the rear propeller 203, and improving the thrust and efficiency of the rear propeller 203. This design plays an important role in the ship propulsion system, especially in situations where high-efficiency propulsion is required.

[0042] In another embodiment, the twist angle in the second pre-whirl section S2 monotonically decreases from the demarcation line A0 to the tip A2. The smaller twist angle makes the nose-tail line of the strut body 100 body cross section approach the flow field in front of it, thereby reducing the shape resistance of the strut body 100 body. The design of the twist angle of the second pre-whirl section S2 further optimizes the overall hydrodynamic performance of the propeller by reducing the shape resistance of the strut body 100 in the near-tip A2 region. The reduction of the shape resistance means that the propeller needs to overcome less resistance during operation, thereby reducing energy loss and improving propulsion efficiency. This has a positive effect on improving the speed and fuel economy of the ship.

[0043] The twist angle distribution of the pre-whirl section makes the nose-tail line of the strut body 100 cross section approach the flow field direction, and the maximum value of the twist angle in the first pre-whirl section S1 is not more than 5°, and the maximum value of the twist angle in the second pre-whirl section S2 is not more than 3°. This twist angle distribution design precisely controls the flow direction of the fluid, so that the strut body 100 can maintain good hydrodynamic performance in different regions. The twist angle limitation of the first pre-whirl section S1 and the second pre-whirl section S2 ensures that the strut body 100 does not generate excessive resistance during operation, while ensuring the efficiency of the rear propeller 203. This design has a wide application prospect in the ship propulsion system.

[0044] Embodiment Two

[0045] As Figure 5As shown, the embodiment discloses a design method of a twisted pod strut of a contra-rotating full-revolving propeller. The three-dimensionally twisted contra-rotating full-revolving propeller strut body 100 designed in the embodiment helps to improve the hydrodynamic efficiency of the rear propeller 203 and reduce the form drag of the strut body 100. However, when the specific design parameters of the three-dimensionally twisted shape of the full-revolving propeller strut body 100 are different, the hydrodynamic efficiency of the rear propeller 203 and the form drag of the strut body 100 are different. Therefore, the application also provides a design method for designing the twisted pod strut body 100 of the full-revolving propeller. The specific design parameters are obtained by evaluating the hydrodynamic performance indicators of the related components of the full-revolving propeller. The design method can be realized by programming in Basic / Python and other languages. This design method can accurately control the three-dimensionally twisted shape of the strut body 100 by comprehensively considering the hydrodynamic performance indicators of each component of the propeller, thereby optimizing the overall performance of the propeller. Programming implementation makes the design process more efficient and accurate, which helps to shorten the design cycle and reduce the design cost. Please refer to Figure 5 The flowchart shows that the design method includes the following steps:

[0046] Step 1, determine the main design parameters of the strut body 100 and the distribution of the strut body 100 cross-section rotation angle. The strut body 100 cross-section rotation angle is a design parameter of the twisted pod strut body 100 of the full-revolving propeller. The three-dimensionally twisted contra-rotating full-revolving propeller strut body 100 according to the application includes: the area of the strut body 100 between the root A1 of the strut body 100 intersecting with the casing 201 to the demarcation line A0 is the first pre-rotation section S1, the rotation direction of the strut body 100 is the same as that of the rear propeller 203, the twist angle is large, and the maximum value is obtained at the root A1; the demarcation line A0 to the tip A2 of the strut body 100 is the second pre-rotation section S2, the rotation direction of the strut body 100 is the same as that of the rear propeller 203, the twist angle is small, and the minimum value is obtained at the tip A2. The determination of this design parameter can accurately control the three-dimensionally twisted shape of the strut body 100 by comprehensively considering the operating conditions and performance requirements of the propeller, thereby optimizing the overall performance of the propeller. The twist angle design of the first pre-rotation section S1 and the second pre-rotation section S2 enables the strut body 100 to play different roles in different areas, which not only improves the efficiency of the rear propeller 203, but also reduces the form drag of the strut body 100.

[0047] As mentioned above, the three-dimensional twisted shape of the strut body 100 can be defined by the distribution of the twist angle of the strut body 100 cross section along the height ratio of the strut body 100, and thus the twist angle design parameters include the twist angle of the strut body 100 cross section at different vertical positions (height ratio of the strut body 100). The twist angle of the twisted pod strut body 100 cross section is monotonically non-increasing from the root A1 to the first pre-twist section S1 of the demarcation line A0, and monotonically decreasing from the demarcation line A0 to the second pre-twist section S2 of the tip A2 of the strut body 100. This twist angle distribution design precisely controls the twist angle of the strut body 100 at different vertical positions, so that the strut body 100 can adapt to different attack angle conditions, thereby optimizing the hydrodynamic performance of the propeller. The twist angle variation law of the first pre-twist section S1 and the second pre-twist section S2 ensures that the strut body 100 can maintain good stability and reliability during operation.

[0048] Further, when the twist angle of the cross section of the contra-rotating full-rotation propeller twisted pod strut body 100 in the first pre-twist section S1 from the root A1 of the strut body 100 to the demarcation line A0 remains unchanged or linearly decreases, and the twist angle of the cross section of the twisted pod strut body 100 in the second pre-twist section S2 from the demarcation line A0 to the tip A2 of the strut body 100 linearly decreases. The twist angle design parameters include the root A1 cross section twist angle a1, the cross section twist angle a0 at the demarcation line A0 (if the first pre-twist section S1 twist angle is constant, then a0 = a1), and the tip A2 cross section twist angle a2, which can represent the twist angle distribution curve of the cross section of the contra-rotating full-rotation propeller strut body 100 along the vertical direction. The determination of this twist angle design parameter can precisely control the three-dimensional twisted shape of the strut body 100 by comprehensively considering the operating conditions and performance requirements of the propeller. The twist angle design parameters of the root A1, the demarcation line A0 and the tip A2 make the strut body 100 play different roles in different regions, which not only improves the efficiency of the rear paddle 203, but also reduces the form drag.

[0049] Please refer to Figures 3-4The rotation angle distribution curve of the shown strut body 100 along the height ratio of the strut body 100, in one embodiment, the strut body 100 cross-section rotation angle keeps constant a1 along the height ratio of the strut body 100 in the first pre-rotation section S1, linearly decreases after reaching the boundary line A0 into the second pre-rotation section S2, and linearly decreases to a2 at the tip A2 of the strut body 100; the rotation angle distribution curve of the strut body 100 in the second scheme linearly decreases in the first pre-rotation section S1 along the height ratio of the strut body 100, decreases to a0 at the boundary line A0, and then continues to decrease in the second pre-rotation section S2 until the tip A2 pre-rotation angle decreases to the minimum value a2. These two rotation angle distribution curve designs change in different ways, so that the strut body 100 can adapt to different attack angle conditions. The first scheme keeps the constant rotation angle in the first pre-rotation section S1, so that the rear paddle 203 obtains a larger attack angle increase; the second scheme linearly decreases the rotation angle in the first pre-rotation section S1, so that the strut body 100 can better adapt to the change of flow rate. Both schemes linearly decrease the rotation angle in the second pre-rotation section S2, further reducing the shape resistance.

[0050] The main design parameters of the strut body 100 include the height of the strut body 100, the cross-section length of the strut body 100, the maximum width of the cross-section, and the cross-section distribution form. The height of the strut body 100 is determined by the propeller diameter, overall arrangement requirements, etc., which is the vertical distance from the lowest point of the intersection line of the strut body 100 and the shell 201 to the tip A2 of the strut body 100. The cross-section length and maximum width of the strut body 100 are determined by structural strength and internal transmission device size, and the cross-section form is like the common NACA66mod. The determination of the main design parameters of the strut body 100 considers the operation conditions of the propeller, structural strength, and internal transmission device size, etc., to ensure that the strut body 100 can meet various performance requirements in the design process. The design of the height, cross-section length, and maximum width of the strut body 100 has an important influence on the overall performance and stability of the propeller.

[0051] Step 2, according to the main design parameters of the strut body 100 and the cross-section rotation angle distribution, establish each vertical cross-section sketch.

[0052] According to the main design parameters of the contrarotating full-rotating propeller strut body 100 and the diameter of the rear propeller 203, the vertical positions corresponding to the root A1, the tip A2 and the boundary line A0 of the strut body 100 are determined, and the sketch planes are established respectively. According to the main design parameters such as the cross-sectional length, the maximum width and the cross-sectional distribution form of the strut body 100 and the twist angle, the cross-sectional sketch of the strut body 100 is drawn on the sketch plane. The sketch drawing refers to the existing method, and the step will not be described here. This step provides a basis for the subsequent three-dimensional model establishment by establishing each vertical cross-sectional sketch. The establishment of the sketch plane and the drawing of the cross-sectional sketch need to accurately control each parameter to ensure that the three-dimensional shape of the strut body 100 meets the design requirements.

[0053] Step 3, according to the cross-sectional sketch of the strut body 100, the three-dimensional model of the strut body 100 is established. The cross sections are selected from the root A1 to the tip A2 of the strut body 100 in turn to establish a multi-section surface model, and the shape of the intermediate section can be controlled by adding guide lines. After filling the cross sections of the root A1 and the tip A2, the multi-section surface is sutured, and then the solid model of the closed surface of the strut body 100 can be formed. The solid modeling method refers to the existing method, and the step will not be described here. This step makes the design process more intuitive and accurate by establishing the three-dimensional model of the strut body 100. The establishment of the multi-section surface model and the addition of the guide line help to control the shape of the intermediate section, so as to ensure that the three-dimensional shape of the strut body 100 meets the design requirements. The establishment of the closed surface solid model provides a basis for the subsequent hydrodynamic calculation and performance evaluation.

[0054] Step 4, the three-dimensional model of the propeller model and the shell 201 model are combined to form a full-rotating propeller hydrodynamic calculation model. The three-dimensional model of the shell 201 and the three-dimensional model of the front and rear propellers are added to the three-dimensional model of the strut body 100 established in the previous step according to the relative position relationship, and the Boolean operation is completed to form an integrated three-dimensional hydrodynamic model of the contrarotating full-rotating propeller including the shell 201, the strut body 100, the front propeller 202 and the rear propeller 203. The full-rotating propeller hydrodynamic modeling refers to the existing method, and the step will not be described here. This step combines the three-dimensional models of each component to form an integrated three-dimensional hydrodynamic model of the contrarotating full-rotating propeller.

[0055] Step 5, the hydrodynamic performance of each component of the contrarotating full-rotating propeller is evaluated by using numerical method. The thrust, torque of the rear propeller 203 and the resistance of the strut body 100 are mainly evaluated, and the numerical calculation of the above three-dimensional hydrodynamic model is carried out by using the existing method, and the step will not be described here. This step evaluates the hydrodynamic performance of each component of the propeller by numerical method, which can accurately control the design parameters of the propeller to optimize the overall performance of the propeller. The evaluation of the thrust, torque of the rear propeller 203 and the resistance of the strut body 100 plays an important role in improving the efficiency and reducing the resistance of the propeller.

[0056] Step 6: Adjust the design parameters of the rotation angle of the support body 100 section until the azimuth thruster support body 100 meets the design requirements, thus obtaining the design scheme of the twisted pod support body 100. When the rotation angle design parameters include the rotation angle α1 of the root section A1 of the support body 100, the rotation angle α0 of the boundary line section A0, and the rotation angle α2 of the tip section A2 of the support body 100, the design parameters of the rotation angle of the support body 100 section can be adjusted by adjusting at least one of these three angles. This step, by adjusting the design parameters of the rotation angle of the support body 100 section, enables the thruster to meet the design requirements. Adjusting the rotation angle design parameters of the root A1, boundary line A0, and tip A2 allows the support body 100 to play different roles in different regions, improving the efficiency of the rear propeller 203 and reducing form drag.

[0057] In a simulation example, with the same cladding 201 and the same front and rear propellers, a 3D model of a full-rotation thruster matching the traditional symmetrical cross-section support body 100 is shown below. Figure 6 The image shown is a three-dimensional model of the azimuth thruster of a conventional pod support body 100 in related technologies; as shown... Figure 7 The image shows a 3D model of the azimuth thruster for the tortuous pod support body 100 designed using the above method. Under the same simulation conditions, the hydrodynamic efficiency of the rear propeller 203 of the azimuth thruster corresponding to the two support body 100 design schemes is as follows: Figure 8 As shown, at low advance coefficients, the hydrodynamic efficiency of the aft propeller 203 in the two design schemes is not significantly different. At high advance coefficients, the hydrodynamic efficiency of the twisted pod strut body 100 scheme is significantly improved compared to the symmetrical cross-section strut body 100 scheme. This indicates that at high advance coefficients, the twisted pod strut body 100 produces a more significant pre-spinning effect, improving the incoming flow field of the aft propeller 203 and thus enhancing its hydrodynamic efficiency. The drag coefficients of the azimuth thruster cladding 201 and strut body 100 corresponding to the two strut body 100 design schemes are as follows: Figure 9 As shown, within the full range of advance coefficients, the drag coefficient of the tortuous pod support body 100 design is lower than that of the symmetrical section support body 100 design. This indicates that angular rotation within a certain range can reduce the shape drag of the support body 100. The hydrodynamic efficiency of the azimuth thruster unit corresponding to the two support body 100 design schemes is as follows: Figure 10As shown, the twisted sponson strut body 100 scheme exhibits higher hydrodynamic efficiency, especially at high advance coefficients, as it not only improves the efficiency of the aft propeller 203 but also reduces the drag of the strut body 100, thus improving the overall hydrodynamic efficiency of the controllable pitch Z-propeller unit. These simulation examples verify the superiority of the twisted sponson strut body 100 in improving the efficiency of the aft propeller 203 and reducing the shape drag of the strut body 100 by comparing the hydrodynamic performance of different design schemes. The performance improvement at high advance coefficients is particularly significant, indicating that the twisted sponson strut body 100 has more outstanding advantages at high-speed navigation conditions. When sailing at high speed, the impact of fluid on the sponson strut is more intense. The traditional strut, due to its unreasonable shape design, is prone to form large vortexes and separation flows on the surface, which not only increases the shape drag and reduces the propulsion efficiency of the ship, but also adversely affects the inflow conditions of the aft propeller 203, leading to a decrease in the work capacity of the aft propeller 203.

[0058] The twisted sponson strut 100, through its unique twisted shape design, can effectively guide the fluid to flow smoothly along the surface of the strut, reducing the generation of vortexes and the occurrence of separation flows. At high advance coefficients, this advantage is more pronounced, as it enables the fluid to enter the swept area of the aft propeller 203 in a more uniform and stable state after passing through the strut, providing better inflow conditions for the aft propeller 203. The aft propeller 203 operates more efficiently in such a favorable inflow environment, capturing more fluid energy and converting it into forward propulsion of the ship, thereby significantly improving the efficiency of the aft propeller 203.

[0059] At the same time, the reduction of shape drag by the twisted sponson strut 100 plays a key role at high advance coefficients. Due to the reduction of vortexes and separation flows, the friction and pressure distribution between the fluid and the surface of the strut are more reasonable, resulting in a significant reduction in the resistance experienced by the strut. This not only helps to improve the overall propulsion efficiency of the ship and reduce energy consumption, but also reduces the vibration and noise caused by resistance, improving the sailing comfort and stealth of the ship.

[0060] In addition, from the perspective of practical application, the superior performance of the twisted sponson strut 100 provides new ideas and directions for the design and optimization of ships.

[0061] The outstanding performance of the twisted sponson strut 100 at high advance coefficients fully demonstrates its great potential and application value in improving the efficiency of ship propulsion systems, reducing energy consumption, and improving sailing performance. With continuous technological development and improvement, it is believed that the twisted sponson strut 100 will be more widely applied and promoted in the shipbuilding industry, making important contributions to the technological progress and sustainable development of the shipbuilding industry.

[0062] The above description is an explanation of the present application, not a limitation of the present application, the scope of the present application is defined by the claims, within the protection scope of the present application, any form of modification can be made.

Claims

1. A twisted nacelle strut for a contra-rotating zonal thruster, for connecting a hull to a thruster, characterized in that The strut body is connected to the hull and extends outward, and is configured with a tip connected to the hull and a root at the end away from the hull; The contra-rotating propeller is connected to the root of the strut body, and the coaxial front and rear propellers are arranged on the contra-rotating propeller; The axial projection line of the outer edge of the rear propeller disc surface on the strut body is set as a boundary line, and the boundary line divides the strut body into two regions, wherein the first pre-whirl section is located in the axial projection region of the rear propeller disc surface, and the second pre-whirl section is located outside the axial projection region of the rear propeller disc surface; The first pre-whirl section and the second pre-whirl section are both twisted in the same direction, and the twist direction of the pre-whirl section viewed from the tip to the root is the same as the rotation direction of the rear propeller viewed from the rear propeller to the front propeller.

2. A contra-rotating, full-rotation propeller twist-hub strut according to claim 1, wherein, The cross-sectional shape of the strut body is an asymmetric airfoil, the first pre-whirl section is a section of the strut body from the root to the boundary line, and the second pre-whirl section is a section of the strut body from the boundary line to the tip.

3. A contra-rotating, full-rotation propeller twist hanger strut according to claim 2, wherein, The twist angle of each part in the first pre-whirl section is constant, or monotonically decreases from the root of the strut body to the boundary line; the twist angle in the second pre-whirl section monotonically decreases from the boundary line to the tip.

4. A contra-rotating zonal propulsor twist hanger according to claim 3, wherein, The twist angle distribution of the pre-whirl section makes the strut cross-sectional nose-tail line approximate the flow field direction, the maximum twist angle in the first pre-whirl section is not more than 5°, and the maximum twist angle in the second pre-whirl section is not more than 3°.

5. A contra-rotating, full-rotation propeller twist-hub strut according to claim 1, wherein, The contra-rotating propeller includes a casing connected to the strut body, and coaxial front and rear propellers arranged on both sides of the casing and parallel to each other, the diameter of the rear propeller is smaller than the diameter of the front propeller.

6. A method of designing a twisted nacelle strut for a contra-rotating, full-rotation propulsor, the method comprising: The method comprises the following steps: Step 1. Determine the main design parameters of the strut body and the rotation angle distribution, wherein the rotation angle distribution includes the twist angle variation of the first pre-whirl section and the second pre-whirl section; Step 2. Draw the cross-sectional sketch of each vertical position on the sketch plane according to the main design parameters and the rotation angle distribution; Step 3. Establish a multi-section curved surface model and stitch it to form a solid model; Step 4. Combine the model with other components of the propeller to form a hydrodynamic calculation model; Step 5. Evaluate the hydrodynamic performance by numerical method; Step 6. Adjust the rotation angle parameters until the design indicators are met.

7. The method of designing according to claim 6, wherein, The main design parameters include the height, cross-sectional length, maximum width and cross-sectional distribution form of the strut body.

8. The method of claim 6, wherein, The rotation angle distribution parameters include the rotation angle α1 of the root of the strut body on the corresponding horizontal plane, the rotation angle α0 of the boundary line part of the strut body on the corresponding horizontal plane, and the rotation angle α2 of the tip of the strut body on the corresponding horizontal plane, and satisfy: α1≥α0≥α2, and α1≤5°, α2≥0°.

9. The method of designing according to claim 8, wherein, The numerical evaluation includes the calculation of rear propeller thrust, torque and strut resistance; The adjustment of the rotation angle parameters includes the modification of at least one of α1, α0 or α2.

10. The method of claim 6, wherein, The intermediate cross-sectional shape is controlled by the guide line when the solid model is established.

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