Investigation of the turbulence level and the vortex shedding in a turbine cascade working with an organic vapor at subsonic Mach numbers

Abstract

Detailed turbulence and trailing edge vortex shedding measurements employing hot-wire anemometry and numerical simulations using a high-resolution unsteady Reynolds-averaged Navier-Stokes method were conducted for the high subsonic flow of the organic vapor Novec 649 through the VKI turbine cascade at elevated pressure and temperature level. Turbulent spectra downstream and upstream of the cascade were obtained and analyzed. The simulations indicated that acoustics waves (shed shockwaves) and locally supersonic flow occurred at the trailing edge even at a moderate isentropic exit Mach number of 0.7. Strong evidence for that loss-relevant mechanism was found in the hot-wire signals. The vortex shedding frequency depended primarily on the Reynolds number, not the Mach number.