The effect of stator blade compound lean and compound twist on flow characteristics of a turbine stage - numerical study based on 3D NS simulations

摘要

3D shaped blading has become a practise of turbine manufacturers in an effort to raise the efficiency of turbine cycles. The notion of 3D blading encompasses a number of design improvments that are pronounced in reblading stators and rotors, reshaping endwalls and clearances, etc. usually in most advanced designs, all these measures are used in combination in order to improve the turbine performance as much as possible. The paper describes results of numerical investigations of stator blade compound lean and compound twist, and their effect on flow characteristics of short-height HP cylindrical stages of impulse turbines. It is assumed that only stator blades are modified, leaving rotor blades and endwalls unchanged. The overall effect of the tested designs is to redistribute and increase the average values of the mass flow rate and stage reaction, and also increase the flow efficiency. However, the calculations predict that efficiency gains do not exceed 0.4