A method for analyzing pneumatic characteristics and parameters of an independent non-pneumatic tire

Abstract

This invention belongs to the field of numerical simulation technology for non-pneumatic tires, and specifically provides a method for analyzing the aerodynamic characteristics and parameters of independent non-pneumatic tires. S1: Simulation preparation and parameter settings; S2: Mesh independence verification; S3: Steady-state aerodynamic analysis of an independent non-pneumatic tire; S4: Transient aerodynamic analysis of an independent non-pneumatic tire; S5: Analysis of the influence of support parameters on aerodynamic forces and flow field structure. This invention combines steady-state and transient CFD simulations to systematically analyze the aerodynamic characteristics and wake vortex structure of a non-pneumatic tire under rotational conditions, revealing the differences in aerodynamic performance between it and a conventional pneumatic tire, and providing support for the systematic study of the aerodynamic characteristics of non-pneumatic tires.

Description

Technical Field

[0001] This invention relates to the field of numerical simulation technology for non-pneumatic tires, specifically to a method for analyzing the aerodynamic characteristics and parameters of independent non-pneumatic tires. Background Technology

[0002] In recent years, pneumatic tires, as a new type of wheel technology, have gradually entered the automotive field. Compared with traditional pneumatic tires, pneumatic tires can avoid problems such as punctures and leaks, not only improving driving safety but also making them suitable for various complex environments. Michelin successfully developed the first pneumatic tire in 2005, and since then, many domestic and foreign companies and research institutions have successively developed pneumatic tire products with various structures such as honeycomb and fan-blade designs.

[0003] However, non-pneumatic tires, due to their different structural features compared to ordinary pneumatic tires, especially the fan-blade support type non-pneumatic tires which have a fan-like intermediate support structure connecting the rubber platform and the rim, experience greater air resistance during tire rotation due to airflow. Studies have shown that the drag experienced by ordinary pneumatic tires accounts for approximately 20%-30% of the total vehicle drag during driving, while the aerodynamic drag of fan-blade support type non-pneumatic tires is even greater than that of ordinary pneumatic tires.

[0004] Currently, research on non-pneumatic tires, both domestically and internationally, mainly focuses on functional aspects such as load-bearing capacity and structural strength, with limited research on their aerodynamic characteristics. Existing technologies lack systematic analysis of the aerodynamic characteristics of blade-supported non-pneumatic tires, particularly in-depth research on the relationship between structural parameters of the support structure, such as width, thickness, tilt angle, and radius of curvature, and aerodynamic drag. Therefore, conducting research on independent aerodynamic characteristics and parameter analysis methods for non-pneumatic tires is of great significance for reducing aerodynamic drag and improving overall vehicle aerodynamic performance. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution: A method for analyzing the aerodynamic characteristics and parameters of an independent non-pneumatic tire includes the following steps: S1: Simulation preparation and parameter settings: Establish a computational domain with a total length of 12.9m, a width of 1.575m, and a height of 1.68m. The calculated blocking ratio for this simulation is 3.9%. The tire parameters are set as follows: diameter 0.416m, tread width 0.108m, and total width 0.190m. A compound rotation method is used for the simulation. S2: Mesh independence verification: Different schemes are designed by changing the mesh size of the encrypted area, and the scheme with the stable aerodynamic drag coefficient is selected; S3: Steady-state aerodynamic analysis of an independent non-pneumatic tire: First, the steady-state simulation characteristics of an independent non-pneumatic tire are studied. For steady-state simulation, a velocity scalar is established in... The vorticity map with contour lines at -600; S4: Transient Aerodynamic Analysis of Independent Non-Pneumatic Tires: This study utilizes simulation to investigate the aerodynamic characteristics and flow field mechanism of fan-shaped non-pneumatic tires under transient conditions. Based on transient calculations, the average drag coefficient, average lift coefficient, and range fluctuations of the non-pneumatic tire are obtained. The vortex structure in the wake region of the non-pneumatic tire is analyzed to determine the cause of its formation. Pressure isosurfaces are analyzed to confirm the existence of low-pressure regions, and their location, size, and intensity are quantitatively analyzed. S5: Analysis of the Influence of Support Parameters on Aerodynamics and Flow Field Structure: By setting up two sets of tires with different widths based on the tire's own structural constraints, the influence of the support width on the flow field structure is analyzed; by setting up two sets of tires with different thicknesses based on the tire's own structural constraints, the influence of the support thickness on the flow field structure is analyzed; by setting up two sets of tires with different tilt angles based on the tire's own structural constraints, the influence of the support tilt angle on the flow field structure is analyzed; by setting up two sets of tires with different radii of curvature based on the tire's own structural constraints, the influence of the support radius of curvature on the flow field structure is analyzed.

[0007] As a preferred embodiment of the independent non-pneumatic tire aerodynamic characteristics and parameter analysis method described in this invention, the non-pneumatic tire model is further simplified before step S1: the spoke portion is directly deleted, and the tire surface is smoothed for the processing of the tire surface pattern.

[0008] As a preferred embodiment of the independent non-pneumatic tire aerodynamic characteristics and parameter analysis method described in this invention, the wheel wake vortex structure in S4 includes a shoulder vortex, a near-ground vortex, and a tail airflow split. The shoulder vortex is located on the rear side of the wheel; the near-ground vortex is located at the bottom of the wheel and the ground contact point; and the tail airflow region is caused by the separation of airflow generated at the top of the wheel.

[0009] As a preferred embodiment of the independent non-pneumatic tire aerodynamic characteristics and parameter analysis method described in this invention, the low-pressure region in S4 includes: the front edge of the wheel, the inner cavity region of the rim, the separation at the top of the wheel, and the wake region formed at the rear of the wheel.

[0010] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention combines steady-state and transient CFD simulations to systematically analyze the aerodynamic characteristics and wake vortex structure of non-pneumatic tires in a rotating state, revealing the differences in aerodynamic performance between them and ordinary pneumatic tires, and providing support for the systematic research on the aerodynamic characteristics of non-pneumatic tires.

[0011] 2. For non-pneumatic tires with blade support, the influence of four key parameters—support width, support thickness, support tilt angle, and support radius of curvature—on aerodynamic forces and flow field structure was systematically studied. It was found that the support width is negatively correlated with aerodynamic drag, the support thickness is positively correlated with aerodynamic drag, while the support tilt angle and radius of curvature have a nonlinear relationship with aerodynamic drag. As their values ​​increase, the aerodynamic drag first decreases and then increases.

[0012] 3. Through detailed analysis of the vortex system structure in the wake region, key flow field characteristics such as shoulder vortex, near-ground vortex, and tail airflow separation were identified. Combined with pressure isosurface analysis, the location and intensity of the low-pressure zone and its influence mechanism on differential pressure drag were clarified, providing theoretical support for the aerodynamic optimization of non-pneumatic tires. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a schematic diagram of the computational domain in an embodiment of the aerodynamic characteristics and parameter analysis method for an independent non-pneumatic tire according to the present invention; Figure 2 This is a verification diagram of mesh independence in an embodiment of the independent non-pneumatic tire aerodynamic characteristics and parameter analysis method of the present invention; Figure 3 This is a schematic diagram of a mesh in an embodiment of the aerodynamic characteristics and parameter analysis method for an independent non-pneumatic tire according to the present invention; Figure 4 In an embodiment of the aerodynamic characteristics and parameter analysis method for an independent non-pneumatic tire of the present invention, the speed scalar is... The isopleth vorticity diagram for -600; Figure 5 In an embodiment of the aerodynamic characteristics and parameter analysis method for an independent non-pneumatic tire of the present invention, the wake vortex structure around the wheel of the non-pneumatic tire is shown. =-600 isosurface plot; Figure 6 In an embodiment of the aerodynamic characteristics and parameter analysis method for an independent non-pneumatic tire according to the present invention, the overall instantaneous wake vortex structure of the non-pneumatic tire is shown. =-600 isosurface plot; Figure 7 This is a convolutional profile of the instantaneous velocity line at 2.5s in an embodiment of the aerodynamic characteristics and parameter analysis method for an independent non-pneumatic tire of the present invention. Figure 8 In an embodiment of the aerodynamic characteristics and parameter analysis method for an independent non-pneumatic tire of the present invention, CFD contour lines show the instantaneous velocity magnitude near the wheel contact plate; Figure 9 In an embodiment of the aerodynamic characteristics and parameter analysis method for an independent non-pneumatic tire of the present invention, CFD contour lines show the instantaneous velocity near the wheel contact with the ground. Figure 10 This is an isosurface diagram of pressure of an independent non-pneumatic tire in an embodiment of the aerodynamic characteristics and parameter analysis method of an independent non-pneumatic tire according to the present invention. Figure 11 This is a line graph showing the steady-state aerodynamic drag coefficient of a non-pneumatic tire with different support widths in an embodiment of the aerodynamic characteristics and parameter analysis method of an independent non-pneumatic tire according to the present invention. Figure 12 This is a velocity convolution diagram of different wake sections at 1.5s for tires with different support widths in an embodiment of the aerodynamic characteristics and parameter analysis method for independent non-pneumatic tires of the present invention. Figure 13 This is a velocity convolution diagram of tires with different support widths at different times at the Z=0 section in an embodiment of the aerodynamic characteristics and parameter analysis method of an independent non-pneumatic tire of the present invention. Figure 14 This is a line graph showing the steady-state aerodynamic drag coefficient of a non-pneumatic tire with different support body thicknesses in an embodiment of the aerodynamic characteristics and parameter analysis method of an independent non-pneumatic tire of the present invention. Figure 15 This is a velocity convolution diagram of different wake sections at 1.5s for tires with different support thicknesses in an embodiment of the aerodynamic characteristics and parameter analysis method for independent non-pneumatic tires of the present invention. Figure 16 This is a velocity convolution diagram of tires with different support thicknesses at different times at the Z=0 section in an embodiment of the aerodynamic characteristics and parameter analysis method of an independent non-pneumatic tire of the present invention. Figure 17This is a line graph showing the steady-state aerodynamic drag coefficient of a non-pneumatic tire at different support tilt angles in an embodiment of the aerodynamic characteristics and parameter analysis method of an independent non-pneumatic tire according to the present invention. Figure 18 This is a velocity convolution diagram of different wake sections at 1.5s for tires with different support tilt angles in an embodiment of the aerodynamic characteristics and parameter analysis method for independent non-pneumatic tires of the present invention. Figure 19 This is a velocity convolution diagram of tires at different times at the Z=0 section, with different support tilt angles, in an embodiment of the aerodynamic characteristics and parameter analysis method of an independent non-pneumatic tire of the present invention. Figure 20 This is a line graph showing the steady-state aerodynamic drag coefficient of a non-pneumatic tire with different support body curvature radii in an embodiment of the aerodynamic characteristics and parameter analysis method of an independent non-pneumatic tire of the present invention. Figure 21 This is a velocity convolution diagram of different wake sections at 1.5s for tires with different support curvature radii in an embodiment of the aerodynamic characteristics and parameter analysis method for independent non-pneumatic tires of the present invention. Figure 22 This is a velocity convolution diagram of tires at different times at the Z=0 section, representing an embodiment of the aerodynamic characteristics and parameter analysis method for an independent non-pneumatic tire according to the present invention. Detailed Implementation

[0014] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0015] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0016] Example Simplified non-pneumatic tire model: The spokes are directly deleted. The tire surface pattern is smoothed. The tire parameters are shown in Table 1, and the support parameters are shown in Table 2. Table 1: Tire Parameters

[0017] Table 2: Support Parameters

[0018] A method for analyzing the aerodynamic characteristics and parameters of an independent non-pneumatic tire includes the following steps: S1: Simulation preparation and parameter settings: such as Figure 1As shown, the diameter D of the non-pneumatic tire is 0.6m, the distance from the front of the computational domain to the tire center is 4.5m, the distance from the rear of the computational domain to the tire center is 8.28m, the distance to the left and right of the tire is 0.7525m, and the height of the computational domain is 1.68m. The calculated blockage ratio in this simulation is approximately 4.2%, which is less than the required 5%, and meets the simulation requirements. To save computational resources, the front half of the ground is set as a sliding wall, and the motion state is set to stationary. The rear half of the ground is set as a non-slip wall, and the motion speed is set to 18.6m / s. The tire parameters are set as follows: diameter 0.416m, tread width 0.108m, total width 0.190m. A composite rotation method is used for the simulation. S2: Mesh Independence Verification: Different schemes are designed by changing the mesh size of the encrypted area. This embodiment lists 6 mesh schemes for discussion, where parameters include the presence of an encrypted area and the mesh size of the encrypted area, with volumes of 0.84m×0.385m×0.67m (small), 2.94m×0.415m×0.8m (medium), 3.7m×0.575m×0.95m (large), and 5.3m×0.875m×1.05m (extra large). The results of each scheme are shown in Table 3, and a line graph is drawn based on the table (…). Figure 2 ),Depend on Figure 2 It can be seen that the aerodynamic drag coefficient tends to stabilize when the number of grids exceeds ten million. Based on convergence analysis, the fifth grid scheme was chosen.

[0019] Table 3: Detailed values ​​for each grid scheme

[0020] In addition, a total of 10 boundary layer meshes were set, with a growth ratio of 1.1. Based on mesh independence analysis, and considering both computational resources and accuracy, scheme 5 was selected for mesh configuration. Its mesh representation is as follows: Figure 3 As shown.

[0021] S3: Steady-state aerodynamic analysis of an independent non-pneumatic tire: First, the steady-state simulation characteristics of an independent non-pneumatic tire are studied. For steady-state simulation, the velocity scalar is... The isopleth vorticity diagram for -600 is shown below. Figure 4 As shown, directly behind the tire, there is a wake consisting of an inverted "T" structure; two pairs of counter-rotating vortices and their induced velocities dominate the flow field, with the upper pair being the dominant one.

[0022] The pair of lower-positioned vortices are significantly weaker and have little impact on the mean flow field. There are no ground-based vortices originating from the contact surface; therefore, the presence of reverse vortices likely depends on the wheel geometry. Downstream, the wake from the upper part of the tire is transferred to the lower part via the downward entrainment mechanism of the upper vortices. These vortices descend towards the ground due to mutually induced velocities and merge with the lower vortices. Therefore, with increasing downstream distance, the overall wake naturally shortens and expands laterally. S4: Transient Aerodynamic Analysis of Independent Non-Pneumatic Tires: Based on transient calculations, the average drag coefficient, average lift coefficient, and range fluctuations of the non-pneumatic tires are obtained, as shown in Table 4. The variation range of aerodynamic drag is relatively small, while the variation range of the aerodynamic lift coefficient is relatively large. The aerodynamic drag coefficient of a conventional wheel is around 0.51, and the aerodynamic lift coefficient is around 0.35. Therefore, it can be concluded that the aerodynamic drag of the blade-supported non-pneumatic tire is greater than that of a conventional pneumatic tire, while the aerodynamic lift is not significantly different.

[0023] Table 4: Instantaneous calculation of the aerodynamic force of the initial non-pneumatic tire

[0024] Figure 5 The diagram shows the wake vortex structure around an independent, non-pneumatic tire wheel, which can be mainly divided into three distinct parts: the shoulder vortex, the near-ground vortex, and the tail airflow split. The shoulder vortex is located behind the wheel and is formed by the separation of the upper airflow and its collision with the airflow on the side of the wheel. The near-ground vortex is located at the bottom of the wheel and the ground contact point, originating from the airflow in front being obstructed by the bottom of the wheel and rotating outwards, moving along the positive X-axis near the ground. The tail split region is caused by the detachment of airflow generated at the top of the wheel. We can clearly see the composition of the vortex near the independent tire and its interaction with the surrounding environment.

[0025] Shoulder vortices exhibit periodic intensity fluctuations and positional changes, with their main development dynamics including stripping and lateral movement. Near-surface vortices, on the other hand, show more subtle periodic stripping behavior and gradually merge with the separated fluid at the tail. In the X-axis direction, near-surface vortices can extend further, meaning that after a certain distance from the wheel, the shoulder vortex disappears first, while the near-surface vortex persists. Non-pneumatic tires also exhibit similar wake characteristics to conventional tires. A significant difference is that non-pneumatic tires generate wavy vortices at the tire sidewall support, a result of the support structure.

[0026] The overall instantaneous wake vortex structure of a non-pneumatic tire, such as Figure 6 As shown, it can be observed that the instantaneous wake vortex structure differs from the steady-state vortex structure. Immediately following the rotor, the wake continues to exhibit an inverted "T"-shaped topology with a pair of upper vortices, but dominated by randomly distributed vortices.

[0027] like Figure 7 The convolution profile of the instantaneous velocity lines at 2.5 s is shown in the figure. As the wake evolves downstream, the upper vortices continue toward the ground, but not as far downstream as in the steady state at this point. This indicates that their dissipation rate is temporally unstable due to the intense bombardment of the vortices, thus suggesting that their presence downstream is time-varying. Immediately downstream of the wheel, the separation shear layer at the top and sides of the wheel combines with the unstable boundary of the contact area with the ground.

[0028] In the upper part of the wake, such as Figure 8 As shown, the transverse recirculating vortices continue to exist alongside the upper vortices. However, due to the severity of the turbulence, the coherence of these flow characteristics is lost. This turbulence also affects the position and size of these vortices, which no longer exhibit symmetry with their steady-state positions, thus highlighting the importance of considering wake instabilities.

[0029] In the lower half of the wake, Figure 9 The image shows the wake state from the ground contact point. Similar to the upper part of the wake, the boundaries of the flow characteristics are not well defined due to the turbulent nature of the wake. As the wake progresses downstream, it decomposes into randomly distributed eddies without coherent structure.

[0030] Because turbulence exists in both the upper and lower vortices, the intensity of both vortex pairs varies with time. Furthermore, due to the relative weakness of the lower vortex pair, its presence also varies with time. Although the opposing rotating vortex pairs in steady-state simulations have the same intensity instantaneously, this rarely occurs. Therefore, due to the combination of these factors, the downstream amplitude varies with time. This downstream variation causes a change in the width of the lower half of the wake, as shown by a pair of flow-oriented unstable regions. Thus, the wake widens as the downstream width increases relative to the average.

[0031] Studies of the instantaneous wake reveal that it is primarily controlled by randomly distributed macroscopic eddies. In the upper half of the wake, there are transverse recirculating eddies and a pair of counter-rotating upper eddies, but their positions are varied and deformed due to the turbulence embedded within them. In the lower half of the wake, the wake formed upon contact with the ground is similar to that in steady state, but decomposes into randomly distributed eddies. As the wake evolves downstream, the upper eddies do not extend as far downstream as in steady state due to turbulence, thus exhibiting temporal instability in their downstream presence.

[0032] Analysis of the wake instability reveals that the wake formed upon contact with the ground is unstable and exhibits contraction-expansion behavior. Downstream of the non-pneumatic tire, two distinct motions emerge. The first is lateral velocity fluctuation, most prevalent in the lower half of the wake, with the upstream contraction-expansion behavior considered the cause of this overall motion. The second is vertical velocity fluctuation, concentrated in the downstream region induced by eddies, primarily due to the temporal instability of the upper and lower eddies. This fluctuation also affects the width of the lower half of the wake. Lateral slapping motion dominates at half the diameter behind the non-pneumatic tire. This fluctuation is caused by the counter-coupling of merging, counter-rotating vortex pairs; unlike in steady state, the vortex pairs tend to have unequal strengths. Therefore, weaker vortices cannot move downstream as much as stronger vortices, and their positions change over time. This collectively contributes to the imbalance of vortex-induced velocities within the wake.

[0033] Total pressure isosurface Figure 10 The data shows several low-pressure areas around the non-pneumatic tire: First, at the front edge of the wheel, a low-pressure area formed by airflow acceleration, with the total pressure dropping below -160 Pa. Second, the inner rim cavity exhibits a low-pressure area with a total pressure level between -80 Pa and -40 Pa, due to the tire's obstruction reducing airflow. Third, at the wheel tip, a separation zone with a total pressure below -40 Pa is observed, especially at the core of the wheel shoulder vortex structure, where the local total pressure drops below -120 Pa. Fourth, the wake region formed at the wheel's rear exhibits a near-wheel area with a total pressure between -120 Pa and -40 Pa, and a far-wheel area with a total pressure between -40 Pa and 0 Pa. Finally, the vortex structure close to the ground, with a total pressure between -120 Pa and -40 Pa, gradually merges with the wheel wake region. The existence of these low-pressure areas helps in understanding the formation of differential drag and facilitates quantitative analysis of its location, size, and intensity.

[0034] When relative airflow passes over a non-pneumatic tire, the airflow at the leading edge of the tire is obstructed, its velocity decreases, and its pressure increases; while at the trailing edge, the airflow separates, forming a vortex zone, and the pressure decreases. This pressure difference between the front and rear of the non-pneumatic tire creates drag. This drag is called differential drag, and it is the effect of the aforementioned low-pressure zone. During the rotation of the non-pneumatic tire, the low-pressure zone exhibits periodic changes, which is the main reason for the periodic changes in tire stress. S5: Analysis of the influence of support parameters on aerodynamics and flow field structure: The influence of the width of the support on the flow field structure: The original model of the non-pneumatic tire has a support width of 144 mm. In order to study the influence of the support thickness on the tire, two additional widths of 105 mm and 165 mm were set according to the structural constraints of the tire itself.

[0035] The average aerodynamic forces of non-pneumatic tires with three different support widths are shown in Table 5. A dotted line is plotted based on Table 5. Figure 11 The figure shows a clear linear relationship between the wind resistance experienced by the non-pneumatic tire during operation and the thickness of the support structure. Wind resistance decreases as the width of the support structure increases. At a support structure width of 105 mm, both the wind resistance and lift of the sector-type non-pneumatic tire are at their maximum. The drag coefficient increases by 44 counts compared to the original model, and the lift coefficient increases by 12 counts. When the support structure width is 165 mm, the drag coefficient decreases by 39 counts compared to the original model, and the lift coefficient decreases by 68 counts. Overall, the width of the support structure has the greatest impact on the tire's aerodynamic characteristics among the four parameters of the support structure.

[0036] Table 5: Steady-state aerodynamic forces of non-pneumatic tires with different support widths

[0037] like Figure 12 The figure shows the velocity convolution plots at different wake positions along the X-axis (sections X=0.5D, X=0.6D, X=0.7D, and X=0.9D, where D is the diameter of the non-pneumatic tire) at 1.5 s for three different support widths of non-pneumatic tires. The following conclusions can be drawn from the figure: First, at the cross-section X=0.5D position, the wake morphology of the three non-pneumatic tires is basically the same, all showing the formation of near-ground vortices at the wheel's near-ground position, with these near-ground vortices distributed relatively symmetrically on both sides of the tire.

[0038] Secondly, as the wake extends downstream, the wake vortices of the three types of tires exhibit different patterns: the non-pneumatic tire with a support width of 105mm (hereinafter referred to as W105) experiences vortex separation first. The X=0.9D cross-section shows that it has more vortex structures compared to the other tires, indicating severe airflow separation and resulting in higher overall energy consumption for the non-pneumatic tire. This is the main reason why the W105 non-pneumatic tire generates greater wind resistance compared to the other two types of tires.

[0039] like Figure 13 The figure shows the vector diagram of the velocity versus time at the Z=0 section for different support widths. The following conclusions can be drawn from the figure: First, as the width of the support increases, the internal width of the support gradually approaches the width of the tire surface, and the height difference between the side of the support and the tire surface decreases. This allows the airflow blowing from the front of the tire to transition more smoothly to the rear of the tire, extending the airflow separation point. The reduction in the amount of air entering the support of the non-pneumatic tire causes the airflow vortex inside the front half of the support of the non-pneumatic tire to gradually decrease, reducing the overall energy consumption of the wheel and thus reducing the overall aerodynamic drag of the tire.

[0040] Secondly, regarding the inside of the rim of non-pneumatic tires, it is obvious that the number of gas vortices inside the W165 non-pneumatic tire is significantly less than that inside the other two types of tires. This is also because the increased width of the support body allows the airflow to transition more smoothly to the rear side of the tire, thus reducing the amount of air entering the wheel cavity.

[0041] Influence of Support Thickness on Flow Field Structure: The original non-pneumatic tire model had a support thickness of 7 mm. To study the effect of support thickness on the tire, two additional sets of thicknesses of 4 mm and 10 mm were set. The time-averaged aerodynamic forces of the non-pneumatic tires with these support thicknesses are shown in Table 6. Based on Table 6, a dotted line was plotted. Figure 14 ,from Figure 14 It can be observed that the wind resistance experienced by the non-pneumatic tire during operation has a clear linear relationship with the thickness of the support structure. Wind resistance increases with increasing support structure thickness. When the support structure thickness is 4mm, the sector-type non-pneumatic tire exhibits minimum wind resistance and maximum lift. The drag coefficient decreases by 8 counts compared to the original model, while the lift coefficient remains unchanged. When the support structure thickness is 10mm, the drag coefficient increases by 10 counts compared to the original model, while the lift coefficient decreases by 2 counts. Overall, the thickness of the support structure has a significant impact on the tire's aerodynamic characteristics.

[0042] Table 6: Steady-state aerodynamic forces of non-pneumatic tires with different support thicknesses

[0043] like Figure 15 The figure shows the velocity convolution plots at different wake positions along the X-axis (sections X=0.5D, X=0.6D, X=0.7D, and X=0.9D, where D is the diameter of the non-pneumatic tire) at 1.5 s for three different support thicknesses of non-pneumatic tires. The following conclusions can be drawn from the figure: First, unlike the previous section on support width, at the X=0.5D section, the wakes of the three types of tires exhibit different patterns near the ground in advance. The non-pneumatic tire with a support thickness of 10mm (hereinafter referred to as T10) shows obvious near-ground vortex on the right side, and the near-ground vortices on the left and right sides are severely asymmetrical.

[0044] Second, at the X=0.7D cross section, the T10 non-pneumatic tire experiences vortex separation earlier than the other two types of tires, leading to increased energy consumption. This is the reason for the increased aerodynamic drag of the T10 non-pneumatic tire.

[0045] The above phenomena show that the thickness of the support has a significant impact on the flow field.

[0046] like Figure 16 The figure shows the vector diagram of the velocity versus time at the Z=0 section for different support widths. The following conclusions can be drawn from the figure: First, the increased thickness of the fan-shaped non-pneumatic tire support structure reduces the tire's sidewall ventilation area while keeping the number of supports constant. (Liu Yichen) Studies have found that a smaller ventilation area in the spokes of a conventional wheel reduces overall aerodynamic drag. This paper, however, contradicts this finding, demonstrating that the aerodynamic characteristics of fan-support type non-pneumatic tires cannot be studied using the conventional approach for conventional pneumatic tires. As can be seen from the velocity vector diagram, increasing the thickness of the support disrupts airflow, causing premature airflow separation in the wake region.

[0047] Second, for the interior of a non-pneumatic tire rim, the thickness of the support structure has little impact on the internal flow field. This indicates that wake separation plays a major role in aerodynamic characteristics.

[0048] Influence of support tilt angle on flow field structure: The original non-pneumatic tire model has a support tilt angle of 48.6°. To study the influence of the support tilt angle on the tire, two additional tilt angles of 0° and 60° were set. The time-averaged aerodynamic forces of the non-pneumatic tires at the three angles are shown in Table 7. Based on Table 7, a dotted line was plotted. Figure 17 As can be observed from the figure, the wind resistance experienced by the non-pneumatic tire during driving exhibits a non-linear relationship with the tilt angle. At a tilt angle of 0°, the wind resistance of the fan-shaped non-pneumatic tire is at its maximum, but the lift is not as large as the original model. The drag coefficient increases by 11 counts compared to the original model, while the lift coefficient decreases by 3 counts. At a tilt angle of 60°, the wind resistance and lift experienced by the non-pneumatic tire do not change significantly compared to the original model. This is mainly because the shape of its support structure at 60° is similar to the shape of the support structure in the original model at a tilt angle of 48.6°.

[0049] Table 7: Steady-state aerodynamic forces of non-pneumatic tires at different support tilt angles

[0050] like Figure 18 The figure shows the velocity convolution plots of three non-pneumatic tires at different wake positions along the X-axis at an instant of 1.5s (sections X=0.5D, X=0.6D, X=0.7D, and X=0.9D, where D is the diameter of the non-pneumatic tire). The following conclusions can be drawn from the figure: As the wake propagates downstream, the wake vortices of the three types of tires exhibit different patterns: the non-pneumatic tire with a tilt angle of 0° (hereinafter referred to as A0) experiences vortex separation first. The X=0.9D cross-section shows that it has more vortex structures compared to the other tires, indicating severe airflow separation. This is the reason why the A0 non-pneumatic tire generates greater wind resistance compared to the other two types of tires.

[0051] like Figure 19 The figure shows the vector diagram of the velocity versus time at the Z=0 section for different inclination angles of the support. The following conclusions can be drawn from the figure: First, the wakes of A0 and A60 non-pneumatic tires separate earlier than the original model, increasing energy loss and thus increasing aerodynamic drag.

[0052] Secondly, regarding the inside of the rim of the non-pneumatic tire, it is obvious that there are significantly more gas vortices inside the A60 non-pneumatic tire.

[0053] Overall, the tilt angle of the non-pneumatic tire support has little impact on the flow field structure.

[0054] Influence of Support Curvature Radius on Flow Field Structure: The support curvature radius of the original non-pneumatic tire model is 170 mm. To study the influence of the support curvature radius on the tire, two additional sets of curvature radii were set at 100 mm and 400 mm. The time-averaged aerodynamic forces of the non-pneumatic tires with the three curvature radii are shown in Table 8. Based on Table 8, a dotted line was plotted. Figure 20 The figure shows a non-linear relationship between wind resistance and radius of curvature experienced by the non-pneumatic tire during operation. At a radius of curvature of 100mm, both wind resistance and lift of the sector-shaped non-pneumatic tire are at their maximum, with the drag coefficient increasing by 6 counts and the lift coefficient increasing by 3 counts compared to the original model. At a radius of curvature of 400mm, the drag coefficient increases by 5 counts and the lift coefficient decreases by 3 counts compared to the original model. Overall, the radius of curvature of the support structure has a relatively small impact on the tire's aerodynamic characteristics.

[0055] Table 8: Steady-state aerodynamic forces of non-pneumatic tires with different supports and radii of curvature

[0056] like Figure 21 The figure shows the velocity convolution plots of three non-pneumatic tires at different wake positions along the X-axis at an instant of 1.5s (sections X=0.5D, X=0.6D, X=0.7D, and X=0.9D, where D is the diameter of the non-pneumatic tire). The following conclusions can be drawn from the figure: At section X=0.5D, the wake morphology of the three types of non-pneumatic tires is basically the same, all exhibiting the formation of near-ground vortices near the ground, which are relatively symmetrically distributed on both sides of the tire. The wake region of the non-pneumatic tires shows good symmetry when the basic model and the radius of curvature are 170mm. It can be observed that the radius of curvature of the support has some influence on the wake, but the influence is small. The R100 and R400 non-pneumatic tires show significant airflow asymmetry at section X=0.9D, i.e., airflow separation occurs.

[0057] like Figure 22 The diagram shows the velocity versus time variation of different support radii of curvature at the Z=0 section. From the diagram, we can conclude that the wake separation point of the non-pneumatic tire with a curvature radius of 400mm (hereinafter referred to as R400) is closer to the tire than that of the base model, a finding further supported by this observation from different angles. Furthermore, all three types of tires exhibit periodic wake oscillations in the Y direction.

[0058] This application investigates non-pneumatic tires using CFD numerical simulation. First, an isolated base model of the non-pneumatic tire is studied. The vortex structure in the wake region of the fan-blade-supported non-pneumatic tire exhibits a similar wake vortex structure to that of a conventional pneumatic tire. Then, simulation studies are conducted on the structural parameters of the support structure of the non-pneumatic tire, revealing that the support width and thickness significantly influence the tire's aerodynamic characteristics.

[0059] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for analyzing the aerodynamic characteristics and parameters of an independent non-pneumatic tire, characterized in that, Includes the following steps: S1: Simulation preparation and parameter settings: Establish a computational domain with a total length of 12.9m, a width of 1.575m, and a height of 1.68m. The calculated blocking ratio for this simulation is 3.9%. The tire parameters are set as follows: diameter 0.416m, tread width 0.108m, and total width 0.190m. A compound rotation method is used for the simulation. S2: Mesh independence verification: Different schemes are designed by changing the mesh size of the encrypted area, and the scheme with the stable aerodynamic drag coefficient is selected; S3: Steady-state aerodynamic analysis of an independent non-pneumatic tire: First, the steady-state simulation characteristics of an independent non-pneumatic tire are studied. For steady-state simulation, a velocity scalar is established in... The vorticity map with contour lines at -600; S4: Transient Aerodynamic Analysis of Independent Non-Pneumatic Tires: This study utilizes simulation to investigate the aerodynamic characteristics and flow field mechanism of fan-shaped non-pneumatic tires under transient conditions. Based on transient calculations, the average drag coefficient, average lift coefficient, and range fluctuations of the non-pneumatic tire are obtained. The vortex structure in the wake region of the non-pneumatic tire is analyzed to determine the cause of its formation. Pressure isosurfaces are analyzed to confirm the existence of low-pressure regions, and their location, size, and intensity are quantitatively analyzed. S5: Analysis of the Influence of Support Parameters on Aerodynamics and Flow Field Structure: By setting up two sets of tires with different widths based on the tire's own structural constraints, the influence of the support width on the flow field structure is analyzed; by setting up two sets of tires with different thicknesses based on the tire's own structural constraints, the influence of the support thickness on the flow field structure is analyzed; by setting up two sets of tires with different tilt angles based on the tire's own structural constraints, the influence of the support tilt angle on the flow field structure is analyzed; by setting up two sets of tires with different radii of curvature based on the tire's own structural constraints, the influence of the support radius of curvature on the flow field structure is analyzed.

2. The method for analyzing the aerodynamic characteristics and parameters of an independent non-pneumatic tire according to claim 1, characterized in that, Before S1, a simplified non-pneumatic tire model is also included: the spokes are directly deleted, and the tire surface is smoothed for the tread pattern.

3. The method for analyzing the aerodynamic characteristics and parameters of an independent non-pneumatic tire according to claim 1, characterized in that, The wheel wake vortex structure in S4 includes a shoulder vortex, a near-ground vortex, and a tail airflow split. The shoulder vortex is located on the rear side of the wheel; the near-ground vortex is located at the bottom of the wheel and the ground contact point; and the tail airflow region is caused by the separation of airflow generated at the top of the wheel.

4. The method for analyzing the aerodynamic characteristics and parameters of an independent non-pneumatic tire according to claim 1, characterized in that, The low-pressure region in S4 includes: the front edge of the wheel, the inner cavity of the rim, the separation at the top of the wheel, and the wake region formed at the rear of the wheel.

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