Experimental and numerical investigations on the influence of the tip leakage flow on the radial flow field in a four-stage turbine

A test rig of a four stage axial turbine has been set up at the Institute of Steam and Gas Turbines, Aachen University of Technology, in order to investigate the flow characteristics in the axial gaps before and behind an intermediate stage. Therefore, extensive unsteady measurements have been carried out using a five hole pressure miniature probe. Furthermore, a numerical investigation of the 3-D flow field in the third stage of the test turbine is performed using a steady Navier-Stokes computer code. The calculations include the detailed simulation of the leakage flows using a high resolution grid in the near wall regions.