Measurement and prediction of unsteady blade loads in a supersonic/transonic turbine

Abstract

This paper describes the use of advanced flow analysis for the prediction of unsteady blade forces in a supersonic/transonic turbine. The unsteady flow analysis was used in connection with a full scale turbine blade vibration test, under cold running conditions. In the test, measurements were performed in order to quantify the pressure loads acting on the blades. The first part of the unsteady flow analysis was performed prior to the blade vibration test, in order to get a qualified estimate of the demands upon the pressure transducers used in the test. An enlarged computational model was then used for prediction of the unsteady blade loads in both turbine stages. The blade vibration test with measurement of pressure fluctuations was most valuable for verification of the analysis method. The unsteady flow analysis was successful, and comparing to test results it was shown the predicted unsteady blade load was 10 % from the measured load for the dominating harmonic.