QUANTITATIVE STUDY OF UNSTEADY COMPRESSIBLE FLOW ON AN OSCILLATING AIRFOIL

Real-time interferometric measurements of the flow near the leading ed ge of an oscillating airfoil offer detailed experimental quantificatio n of the locally compressible flowfield that surrounds an oscillating airfoil at moderate subsonic Mach numbers. Interferograms obtained by a specially adapted real-time point-diffraction interferometry techniq ue have revealed some important characteristics or this complex, and v ery rapidly varying, locally supersonic flow. Instantaneous pressure d istributions deter-mined from these interferograms document the effect of unsteadiness on the leading-edge flow environment.