COMPARATIVE EXPERIMENTAL INVESTIGATION ON AERODYNAMIC PERFORMANCE OF STEAM TURBINE CASCADES, PART I - ROTOR BLADES

In this paper, the static aerodynamic performance of the second to last stage rotor blades of a marine steam turbine is experimentally investigated. The experiments have been carried out for both original blade (ORI R1) and modified blade (MOD R1) annular cascades. The experimental results indicate that the straight original blade is aft-loaded type, and there is a large degree of diffusion at the tip end wall. The improvement methods include adopting twist blades, adjusting the blade profile to reach the aft-loaded as much as possible at both end walls as well as combining with the cylindrical meridian lines. It has been found in the experiment that the transverse pressure gradient of the modified decreases at both end walls, so does the loss of the flow, especially it weakens the secondary flow at the tip end wall. The aerodynamic loss coefficient of improved blades has reduced by about 25%.