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aus der Wiesche, Stefan
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aus der Wiesche
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Stefan
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Stefan aus der Wiesche
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Investigation of the turbulence level and the vortex shedding in a turbine cascade working with an organic vapor at subsonic Mach numbersHake, Leander; hanndermeier, SuStep; aus der Wiesche, Stefan; Matar, Camille; Cinnella, Paola; Gloerfelt, XavierDetailed 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.- Calibration of multi-hole probes for measurements in compressible organic vapor flowsHake, Leander; Sundermeier, Stephan; aus der Wiesche, Stefan; Passmann, MaximilianMulti-hole probes are necessary devices to measure flow characteristics and losses in turbomachinery. The present contribution reports the first experience with calibrating and using multi-hole probes in high-speed flows of the organic vapor Novec 649 at elevated pressure and temperature levels. It is found that the classical scheme, established for perfect gas applications, must be extended by an additional quantity reflecting the impact of the initial thermodynamic state on the pressure signals and the data reduction. The practical use and operational issues of three- and five-hole probes for ORCturbomachinery research are discussed based on the new results. A promising hybrid experimentalnumerical calibration approach significantly reduces the tremendous calibration effort.
