An Analysis of Outlet Distortion in LP Steam Turbines

Abstract

In gas and steam turbines, outlet distortions may lead to vibrations of the rotor blades. In order to gain a deeper understanding of origin and intensity of the excitation mechanism, various distorted flow conditions caused by asymmetric exhaust or by ribs were investigated in radial and circumferential direction with the help of pneumatic probes. The periodic pressure fluctuations on the rotor blades, which are responsible for the excitation, were determined with miniature pressure transducers at temperatures of about 100 °C and centripetal accelerations of 65,000 g. The response of the blades was measured by strain gauges. The results obtained can be used for verification of three-dimensional unsteady flow algorithms.