Article Sidebar

Download
PDF
Statistic
Read Counter : 208 Download : 61

Downloads

Download data is not yet available.

Main Article Content

Abstract

This study investigates standard vehicles' flow behavior and drag during crosswind conditions by a numerical approach. The model is a half-scaled Ahmed body with a slant angle of 25°. Reynolds Average Navier-Stokes equations with turbulent model k-ω SST is applied to solve Navier Stokes equation by discrete method. Experimental data validated the numerical results at the same flow conditions. The results indicated that the model's drag increases with yaw angles, which is connected with the development of the longitudinal vortex on the windward side. However, the lift coefficient and pressure drag acting on the slant showed a maximum value at a yaw angle of around 35° before they dropped again. The drop of those coefficients results in the moving upward of the longitudinal vortex above the slant. The complex vortex structures around the base in both cross-sectional and symmetric planes are analyzed. The skin-friction pattern and pressure distribution on the slant are exposed to understand the effect of the yaw angle on aerodynamic forces.

Keywords

Ahmed body Yaw angle Skin friction Separation bubble Longitudinal vortex

Article Details

Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

References

  1. D. Kim, H. Lee, W. Yi, and H. Choi, “A bio-inspired device for drag reduction on a three-dimensional model vehicle,” Bioinspiration and Biomimetics, vol. 11, no. 2, 2016, doi: 10.1088/1748-3190/11/2/026004.
  2. S. R. Ahmed, G. Ramm, and G. Faltin, “Some Salient Features of the Time -Averaged Ground,” SAE Transactions, vol. 93, no. 1984, pp. 473–503, 1984.
  3. A. K. Perry, G. Pavia, and M. Passmore, “Influence of short rear end tapers on the wake of a simplified square-back vehicle: wake topology and rear drag,” Experiments in Fluids, vol. 57, no. 11, pp. 1–17, 2016, doi: 10.1007/s00348-016-2260-3.
  4. Y. A. Irving Brown, S. Windsor, and A. P. Gaylard, “The effect of base bleed and rear cavities on the drag of an SUV,” SAE Technical Papers, 2010, doi: 10.4271/2010-01-0512.
  5. Z. Arifin et al., “Aerodynamic Characteristics of Ahmed Body with Inverted Airfoil Eppler 423 and Gurney Flap on Fastback Car,” Automotive Experiences, vol. 5, no. 3, pp. 355–370, 2022, doi: 10.31603/ae.7067.
  6. T. The Hung, M. Hijikuro, M. Anyoji, T. Uchida, T. Nakashima, and K. Shimizu, “Deflector effect on flow behavior and drag of an Ahmed body under crosswind conditions,” Journal of Wind Engineering and Industrial Aerodynamics, vol. 231, p. 105238, Dec. 2022, doi: 10.1016/j.jweia.2022.105238.
  7. T. Tunay, B. Yaniktepe, and B. Sahin, “Computational and experimental investigations of the vortical flow structures in the near wake region downstream of the Ahmed vehicle model,” Journal of Wind Engineering and Industrial Aerodynamics, vol. 159, no. October, pp. 48–64, 2016, doi: 10.1016/j.jweia.2016.10.006.
  8. A. D. Le, H. Phan Thanh, and H. Tran The, “Assessment of a Homogeneous Model for Simulating a Cavitating Flow in Water Under a Wide Range of Temperatures,” Journal of Fluids Engineering, vol. 143, no. 10, p. 101204, 2021, doi: 10.1115/1.4051078.
  9. T. H. Tran, M. Anyoji, T. Nakashima, K. Shimizu, and A. D. Le, “Experimental Study of the Skin-Friction Topology Around the Ahmed Body in Cross-Wind Conditions,” Journal of Fluids Engineering, vol. 144, no. 3, 2022, doi: 10.1115/1.4052418.
  10. G. Bonnavion et al., “On multistabilities of real car’s wake,” Journal of Wind Engineering and Industrial Aerodynamics, vol. 164, no. January, pp. 22–33, 2017, doi: 10.1016/j.jweia.2017.02.004.
  11. F. J. Bello-Millán, T. Mäkelä, L. Parras, C. del Pino, and C. Ferrera, “Experimental study on Ahmed’s body drag coefficient for different yaw angles,” Journal of Wind Engineering and Industrial Aerodynamics, vol. 157, pp. 140–144, Oct. 2016, doi: 10.1016/j.jweia.2016.08.005.
  12. A. Sciacchitano and D. Giaquinta, “Investigation of the Ahmed body cross-wind flow topology by robotic volumetric PIV,” 2019.
  13. T. Tunay, B. Sahin, and H. Akilli, “Experimental and numerical studies of the flow around the Ahmed body,” Wind and Structures, vol. 17, no. 5, pp. 515–535, 2013, doi: 10.12989/was.2013.17.5.515.
  14. W. Meile, T. Ladinek, G. Brenn, A. Reppenhagen, and A. Fuchs, “Non-symmetric bi-stable flow around the Ahmed body,” International journal of heat and fluid flow, vol. 57, pp. 34–47, 2016, doi: 10.1016/j.ijheatfluidflow.2015.11.002.
  15. T. H. Tran, H. Q. Dinh, H. Q. Chu, V. Q. Duong, C. Pham, and V. M. Do, “Effect of boattail angle on near-wake flow and drag of axisymmetric models: a numerical approach,” Journal of Mechanical Science and Technology, vol. 35, no. 2, pp. 563–573, Feb. 2021, doi: 10.1007/s12206-021-0115-1.
  16. E. Guilmineau, G. B. Deng, A. Leroyer, P. Queutey, M. Visonneau, and J. Wackers, “Assessment of hybrid RANS-LES formulations for flow simulation around the Ahmed body,” Computers and Fluids, vol. 176, no. January, pp. 302–319, 2018, doi: 10.1016/j.compfluid.2017.01.005.
  17. F. Delassaux, I. Mortazavi, E. Itam, V. Herbert, and C. Ribes, “Sensitivity analysis of hybrid methods for the flow around the ahmed body with application to passive control with rounded edges,” Computers and Fluids, vol. 214, p. 104757, 2021, doi: 10.1016/j.compfluid.2020.104757.
  18. C. H. Tsai, L. M. Fu, C. H. Tai, Y. L. Huang, and J. C. Leong, “Computational aero-acoustic analysis of a passenger car with a rear spoiler,” Applied Mathematical Modelling, vol. 33, no. 9, pp. 3661–3673, 2009, doi: 10.1016/j.apm.2008.12.004.
  19. T. Tunay, E. Firat, and B. Sahin, “Experimental investigation of the flow around a simplified ground vehicle under effects of the steady crosswind,” International Journal of Heat and Fluid Flow, 2018, doi: 10.1016/j.ijheatfluidflow.2018.03.020.
  20. A. Rao, G. Minelli, B. Basara, and S. Krajnović, “On the two flow states in the wake of a hatchback Ahmed body,” Journal of Wind Engineering and Industrial Aerodynamics, vol. 173, no. June 2017, pp. 262–278, 2018, doi: 10.1016/j.jweia.2017.10.021.
  21. T. Nakashima, T. Moriuchi, Y. Chao, and I. Kohri, “Wake flow visualization of a simplified vehicle model during flow state change,” ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference, AJKFluids 2019, vol. 3A-2019, no. July, 2019, doi: 10.1115/AJKFluids2019-5404.
  22. C. S. Yuan, S. Mansor, and M. A. Abdullah, “Effect of spoiler angle on the aerodynamic performance of hatchback model,” International Journal of Applied Engineering Research, vol. 12, no. 22, pp. 12927–12933, 2017.
  23. H. Viswanathan, “Aerodynamic performance of several passive vortex generator configurations on an Ahmed body subjected to yaw angles,” Journal of the Brazilian Society of Mechanical Sciences and Engineering, vol. 43, no. 3, pp. 1–23, 2021, doi: 10.1007/s40430-021-02850-8.
  24. F. R. Menter, “Two-equation eddy-viscosity turbulence models for engineering applications,” AIAA journal, vol. 32, no. 8, pp. 1598–1605, 1994, doi: 10.2514/3.12149.
  25. D. A. Johnson and L. S. King, “A mathematically simple turbulence closure model for attached and separated turbulent boundary layers,” AIAA Journal, vol. 23, no. 11, pp. 1684–1692, Nov. 1985, doi: 10.2514/3.9152.
  26. A. A. Matyushenko and A. V. Garbaruk, “Adjustment of the k-ω SST turbulence model for prediction of airfoil characteristics near stall,” Journal of Physics: Conference Series, vol. 769, no. 1, 2016, doi: 10.1088/1742-6596/769/1/012082.
  27. R. Chebli, B. Audebert, G. Zhang, and O. Coutier-Delgosha, “Influence of the turbulence modeling on the simulation of unsteady cavitating flows,” Computers & Fluids, vol. 221, p. 104898, 2021, doi: 10.1016/j.compfluid.2021.104898.
  28. T. H. Tran, M. Hijikuro, M. Anyoji, T. Uchida, T. Nakashima, and K. Shimizu, “Surface flow and aerodynamic drag of Ahmed body with deflectors,” Experimental Thermal and Fluid Science, p. 110887, 2023, doi: 10.1016/j.expthermflusci.2023.110887.