Pressure-Sensitive Paint for Automotive Aerodynamics

Measurement of static pressure over an automotive body is tedious work. The preparation of the model can be long and the spatial resolution in high curvature regions, where separations occur, is poor. To overcome these intrinsic drawbacks it is necessary to use another nonintrusive experimental technique. We show in this paper that the Pressure Sensitive Paint (PSP) fulfills the requirements and is reliable for automotive applications. We consider a simplified 1/4-scale model of a Peugeot 206 with a modified back slant to enhance the longitudinal vortices. The PSP measurements are compared to standard pressure ports measurements and to CFD computations. We find good quantitative agreement between pressure ports and PSP measurements and a good qualitative and quantitative agreement between PSP and the computations over the entire slant surface. The high spatial resolution and high sensitivity of this technique allows very good description of the flow over any complex surfaces even at low velocity. Considering that PSP does not need any particular instrumentation of the car, it is well adapted to the constraints of the automotive industry and appears to be a very attractive improvement of the traditional pressure taps.