Multi-Objective Optimization of Non-Axisymmetric Contoured Endwall for Axial Turbines

Abstract

Non-axisymmetric contoured endwall can reduce aerodynamic loss in axial turbine if the endwall shape is well designed. Meanwhile, contouring of the endwall can change the value of the total heat flux through the endwall, mainly by changing the distribution of heat transfer coefficient and the endwall area. In this study, several optimized non-axisymmetric contoured endwall shapes are found in an annular cascade passage by a multi-objective optimization process to achieve both improved aerodynamic performance in the passage and more beneficial heat transfer characteristics on the endwall. The optimized contoured endwall designs were found and they are all with sunken area in the middle of the passage and risen area in the aft part of the passage near the suction side. In addition, the case with better heat transfer performance features higher area-averaged heat transfer coefficient but with smaller total endwall area. contouring, as compared to the flat endwall. The total heat transfer was reduced by 2% with a 3.1% reduction in the averaged heat transfer coefficient value and a 1.3% increasing of endwall area value.