Session: 10-03-02: Fundamental Issues and Perspectives in Fluid Mechanics - II

Paper Number: 70215

Start Time: Monday, 03:40 PM

70215 - Profile Loss of a Printed Transonic Turbine Cascade 

The present contribution presents the results of an experimental study of profile losses of an additive manufactured linear turbine cascade placed in the test section of a closed-loop organic vapor wind tunnel, or CLOWT for short. This test facility at Muenster University of Applied Sciences has been specially designed for the investigation of organic hot steam flows. The wind tunnel enabled the investigation of high subsonic and transonic organic vapor flows under realistic ORC-turbine flow conditions at elevated pressure and temperature levels. The construction of the turbine grid is based on knowledge already obtained from the open source literature. The blade profile which was chosen for the cascade is known under the name VKI-Sieverding and is often used in gas turbines. One reason for choosing this turbine blade profile was that many studies and results have already been carried out for it. The production of the stainless-steel cascade occurs with the so-called Selective Laser Melting (SLM) method. The investigations are carried out under an organic superheated steam atmosphere. For this organic vapor atmosphere, the of carbon based liquid Novec 649 has been used. In addition, measurements were also carried out in an air atmosphere. With Pitot probes the flow field up- and downstream of the cascade were measuring. In the experiment the inflow turbulence level was of order 0.5 %. The focus of the investigation is the influence of surface roughness on the profile loss dimension. For that, the first step was the original roughness parameters of the metal-printed blades as delivered by the manufacturer were determined, and a first set of flow measurements were performed. Then, the blade surfaces were further finished by a vibratory grinding process, and a second set of flow measurements enabled an assessment of the impact of roughness on profile losses. The profile losses are determined by using three different approaches. On the one hand pressure loss ratios and on the other hand speed loss ratios are considered. Although the Reynolds number level was quite high, it was found that further surface treatment reduces noticeably the profile loss in the case of organic vapor flows through the printed cascade. The study also showed that the profile losses are of approximately the same order of magnitude in a high-speed range despite a residual roughness of the blades. In the lower speed range, the residual roughness had taken a more significant influence. The study was supported by the research program "progres.nrw-Research".

Presenting Author: Leander Hake Muenster University of Applied Sciences

Authors:

Leander Hake Muenster University of Applied Sciences
Stefan aus der Wiesche Muenster University of Applied Sciences