Analysis And Optimization Of A Formula Racing Vehicle’s Flow Field Based On Computational Fluid Dynamics

The analysis and optimization of computational fluid dynamics (CFD) are donefor the flow field of a certain type of Formula Student China (FSC) racing vehicle.The body, frame, engine assembly, wheels, suspension, steering system and manikinmodel are built and assembled by3D modeling software CATIA, after that a windtunnel model is generated for analysis. A meshing software ANSA is firstly used to dogeometric cleanup and surface meshing, and then the volumetric meshing and CFDanalysis are done by CFD software Star-CCM+.The simulation and analysis of the FSC racing vehicle’s flow field are dividedinto two parts: common flow field simulation/analysis and thermal environmentsimulation/analysis. The first part focuses on the flow pattern and aerodynamic forcesat middle and high speed, considering the rotation of wheels, relative motion ofground and the effect of porous medium. The second one involves thermalmanagement of engine cabin and thermal comfort of passenger. The temperature orpower of heating components is set, as well as thermal dynamic properties ofmaterials, considering heat conduction, convection and radiation.The result of common flow field simulation shows that: the prototype’sappearance design is reasonable, and the airflow pattern is smooth; the external flowfield only has common tail vortex; the body’s sealing degree is so high that there isonly low-velocity flow in the internal flow field; the vehicle’s aerodynamic drag andlift is ideal, but the pitch moment is too large at high speed, which is not conducive tohandling stability and needs adjustment.The result of thermal environment simulation shows that: since the prototypeadopts high-closure-body design to realize excellent aerodynamic effect, the heataccumulates to raise the temperature of engine and passenger cabin, and passenger’sthermal comfort becomes bad; the situation is obviously worse at lower speed, and iteven affects the normal operation of automatic fire extinguisher. The prototype’sthermal environment is poor and it needs optimization to improve thermal comfort ofpassenger greatly and to ensure the normal work of components.According to the results of the simulation and analysis, optimization of the prototype is proposed. The specific scheme is:①adding negative lift fin on frontspoiler,②adding intake and exhaust slot at the bottom of body,③increasing thediameter of inlet port and abolishing horizontal guide plate. Through one more CFDsimulation and analysis, a result shows that: after optimization, the aerodynamic dragchanges little, the negative aerodynamic lift increases by27.9%, the pitch moment isgreatly improved, reducing by73.5%; the temperature of passenger cabin is reducedto be consistent with outside environment, and passenger’s thermal comfort becomesfurther better; the high-temperature region of engine cabin decreases, so that theautomatic fire extinguisher will no longer be affected by high temperature to triggerfalsely.