Multigrid CCDPIV measurements of accelerated flow past an airfoil at an angle of attack of 30°

Multigrid cross-correlation digital PIV (MCCDPIV) technique is used to measure the flow field around a NACA 0015 airfoil at a 30degrees angle of attack when the flow is accelerated to a constant velocity from a quiescent state. The experiments were conducted in an acceleration water tunnel using uniform accelerations of 50 and 100 mm/s(2). The final uniform velocity was 100 mm/s for both cases, and the Reynolds number based on this velocity and the chord length of the airfoil was about 8000. The MCCDPIV measurements were carried out using a digital 2048 px x 2048 px CCD camera to record single exposed images of seed particles illuminated with a Nd:YAG laser. These measurements have revealed a rich and complex unsteady flow structure, during both the acceleration phase and the constant velocity post-acceleration phase. (C) 2002 Elsevier Science Inc. All rights reserved.