Wind Tunnel Experiment and Numerical Simulation of the Pressure Distribution on a Sedan Exterior Surface

Abstract

The wind tunnel measurement and numerical simulation of a 50% scaled sedan model surface pressure distribution were made in order to provide fundamental data for improving the Computational Fluid Dynamics (CFD) simulation accuracy of the aerodynamic noise related flow field around automobiles. The pressure measurement positions of the wind tunnel experiment were on the side window and the door. The wind tunnel test section speed was 30m/s at 0° yawing angle. As for the CFD simulation, the wind tunnel shape computational domain and four settings of the near wall computational mesh were made. Both the k-ω SST and the Realizable k-ε turbulence models were chosen. And three value ranges of the near wall computational mesh’s dimensionless wall distance (y+) were realized. Compared with the experimental data, the pressure coefficient (CP) simulation results showed good agreement with the measurement at the re-attaching region on the side window and the attaching region on the door. But the large CPprediction errors happened in the region of the front pillar vortex, the side view mirror wake. It was also shown that the predicted CPvalues were almost independent of the y+value, except the comparatively larger CPpredicted errors on the side window obtained by using the k-ω SST turbulent model when the y+value ranged from 4 to 7. Further unsteady CFD simulation and the exterior aerodynamic noise measurement need be carried out due to the unsteady features of the separated flows, including the front pillar vortex and the side view mirror wake.