Design Optimization of Profiled Endwall in a High Work Turbine

In this paper, a method based on non-uniform rational B-spline surface (NURBS) technique coupled with mesh deforming technique is implemented to design the profiled endwall of turbines. This method has the advantages of flexible geometry representation and automatic rapid remeshing. An optimization procedure has been implemented by integrating the in-house geometry manipulator, a commercial three-dimensional CFD flow solver and the optimization driver, IsightTM.This procedure is applied to design the profiled endwalls of the first stage of a one-and-half stage high work axial flow turbine. Genetic Algorithm is used in the optimization process, and the aim is to minimize the total pressure loss.The influences of the profiled endwalls on the secondary flow in the stator and rotor have been analyzed by steady simulation. The results indicate a 0.4% improvement in stage efficiency. The secondary loss as well as the profile loss has been significantly reduced, and the increase of the reaction which influences the turbine efficiency is also observed.The unsteady simulations are also presented in this paper to confirm the improved performance of the optimum profiled endwalls.Copyright © 2014 by ASME