Determination of boundary layer transition and separation on double arc compressor blades in a large subsonic cascade.

Abstract

The china clay technique for flow visualization was used to determine the surface flow on a double circular arc (DCA) compressor blade in a large rectilinear subsonic cascade wind tunnel. A calibration experiment using a large flat plate model is also reported which allowed the drying patterns on the DCA blading to be interpreted. Natural transition occurred on the flat plate at a Reynolds Number based on transition location of 0.8 x 10⁶, and on the suction surface of the DCA blading at significant negative incidence angles at a Reynolds Number based on transition location of approximately 0.5 x 10⁶. At incidence angles larger than -3⁰ , the DCA blade showed a leading edge separation bubble with turbulent reattachment.