The effects of surface roughness on the aerodynamic drag coefficient of vehicles

Year 2022, , 189 - 195, 30.06.2022

Kemal Ermiş , Mehmet Çalışkan , Anıl Okan

https://doi.org/10.30939/ijastech..1108956

Cited By: 1

Abstract

In this study, the effects of surface roughness differences of vehicle coating materials (paint, paste, special applications, etc.) on the aerodynamic drag coefficient were inves-tigated using the finite element method. For this, aerodynamic drag forces and aerody-namic drag coefficients for speeds between 40-150 km/hours were calculated for a 1/20 scale vehicle designed by a package program by defining the body parts and front-rear window parts separately and assigning pre-calculated roughness values suitable in the industry, and the results were presented through graphs and visuals. Using three different paint roughness values (low, medium, and high), and one commonly used Teflon (fluoropolymer) coating, it was observed that the aerodynamic resistance coefficient in-creased with increasing roughness levels. Relative to the aerodynamic resistance coeffi-cient for the lowest paint roughness value, the aerodynamic resistance coefficient for the medium roughness value showed an increase of 0.000612529%, the aerodynamic resistance coefficient for the high roughness value showed an increase of 0.00104783%, and the aerodynamic resistance coefficient for the fluoropolymer coating showed an increase of 0.091195826%. In addition, the distribution of the pressure forces on the vehicle hood and windscreen were also observed in the study. It was observed that the pressure forces, which were approaching maximum on the front bumper, windscreen and side mirrors, were reduced over the rear windscreen area due to separated flow. It was also observed that the aerodynamic resistance force can be reduced by processes such as angular improvements to be made in the front bumper and vehicle windscreens.

Keywords

Aerodynamics, Drag coefficient, Surface roughness, CFD, Automotive

References

• [1] Asim T, Ubbi K, Mishra R, et al. Effect of surface roughness on the aerodynamic performance of an articulated truck-trailer assembly. In: The 24th Congrès Français de Mécanique (CFM 2019). Brest, France, https://rgu-repository.worktribe.com/output/248528 (2019).
• [2] Mallick K, Wandera L, Bhattarai N, et al. A Critical Evaluation on the Role of Aerodynamic and Canopy–Surface Conductance Parameterization in SEB and SVAT Models for Simulating Evapotranspiration: A Case Study in the Upper Biebrza National Park Wetland in Poland. Water 2018, Vol 10, Page 1753 2018; 10: 1753.
• [3] Qi X, Liu Y, Du G, et al. Experimental and Numerical Studies of Aerodynamic Performance of Trucks. JHyDy 2011; 23: 752–758.
• [4] Rohatgi US. Methods of Reducing Vehicle Aerodynamic Drag Nonproliferation and National Security/Safeguards and Verification Implementa-tion/Building 197D.
• [5] Yakup Içingür. Determination of drag coefficients of various automobile models in a low speed wind tunnel. Fak Der J Fac Eng Arch Gazi Univ Cilt 2011; 26: 455–460.
• [6] Rakibul Hassan SM, Islam T, Ali M, et al. Numerical Study on Aerodynamic Drag Reduction of Racing Cars. Procedia Engineering 2014; 90: 308–313.
• [7] Frank T, Turney J. Aerodynamics of Commercial Vehicles. Lecture Notes in Applied and Computational Mechanics 2016; 79: 195–210.
• [8] Kieffer W, Moujaes S, Armbya N. CFD study of section characteristics of Formula Mazda race car wings. Mathematical and Computer Modelling 2006; 43: 1275–1287.
• [9] Aka H. Study On Aerodynamic Characteristics of a Passenger Car in A Wind Tunnel (M.Sc. Thesis) . Gazi University, 2003.
• [10] Beccaria M, Buresti G, Ciampa A, et al. High-performance road-vehicle optimised aerodynamic design: Application of parallel computing to car design. Future Generation Computer Systems 1999; 15: 323–332.
• [11] Hucho WH, Sovran G. Aerodynamics of Road Vehicles. Annual Review of Fluid Mechanics 2003; 25: 485–537.
• [12] Ozawa H, Nishikawa S, Higashida D. Development of aerodynamics for a solar race car. JSAE Review 1998; 19: 343–349.
• [13] Schenkel FK. The Origins of Drag and Lift Reductions on Automobiles with Front and Rear Spoilers. SAE Technical Papers. Epub ahead of print February 1, 1977. DOI: 10.4271/770389.
• [14] Ramakrishnan V, Soundararaju D, Jha P, et al. A Numerical Approach to Evaluate the Aerodynamic Performance of Vehicle Exterior Surfaces. In: SAE 2011 World Congress & Exhibition. SAE International. Epub ahead of print April 2011. DOI: https://doi.org/10.4271/2011-01-0180.
• [15] Gilhaus A. The influence of cab shape on air drag of trucks. Journal of Wind Engineering and Industrial Aerodynamics 1981; 9: 77–87.
• [16] Çengel YA, Cimbala JM. Fluid mechanics : funda-mentals and applications. 4th Edition. McGraw Hill, 2018.
• [17] White FM. Fluid Mechanics 8e In SI Units. 8 th Edition. Mc Graw Hill, 2016.
• [18] Vazirian MM, Charpentier TVJ, de Oliveira Penna M, et al. Surface inorganic scale formation in oil and gas industry: As adhesion and deposition processes. Journal of Petroleum Science and Engineering 2016; 137: 22–32.
• [19] Streitberger H-Joachim, Kreis Winfried. Automotive paints and coatings. 2008; 493.
• [20] Keleş U. CFD analysis of a tractor-trailer models drag coefficient under crosswind effect. Yildiz Technical University, 2015.
• [21] Launder BE, Spalding DB. The numerical computation of turbulent flows. Computer Methods in Applied Mechanics and Engineering 1974; 3: 269–289.
• [22] Truck, Aerodynamics B, Committee FE. Guidelines for Aerodynamic Assessment of Medium and Heavy Commercial Ground Vehicles Using Computational Fluid Dynamics. Epub ahead of print June 2021. DOI: https://doi.org/10.4271/J2966_202106.