Controlling the Secondary flows in a 90° Turning Duct using Nonaxisymmetric Endwall and Endwall Boundary Layer Fence

摘要

This paper presents the shape optimization of nonaxisymmetric endwall and endwall boundary layer fence which improve the aerothermal characteristics of a gas turbine passage. The endwall and fence in a gas turbine passage effectively reduce secondary flow loss, which is generated in the cascade of the turbine. The endwall and fence methods were used simultaneously. The turbine passage was simulated by a 90° turning duct (ReD=360,000). The main purpose of the present investigation was to focus on finding a nonaxisymmetric endwall and boundary layer fence with minimum total pressure loss in the passage and heat transfer coefficient on the endwall of the duct. An approximate optimization method was used for the investigation to secure the computational efficiency. Design variables were the endwall and fence shape factors. Results indicated that a significant improvement in aerodynamic performance can be achieved through the application of an optimized boundary layer fence. The optimized design reduced the total pressure loss in the duct by 10.2% relative to the duct without the endwall and fence. The Nusselt number on the endwall of the optimized design was decreased by 5.7% in comparison with the duct without the endwall and fence.