Optimization of a nozzle vane of gas turbine pre-swirl system

Gas turbine pre-swirl systems has been known to provide smooth cooling air to rotating turbine blades for prevention of thermal damage caused by high turbine inlet temperatures. The performance of the pre-swirl system depends on the shapes of its components, such as the pre-swirl nozzle and receiver hole. This study focused on obtaining the optimal shape of a pre-swirl nozzle that minimizes aerodynamic losses. To determine the optimal shape with minimal design parameters, we modeled the nozzle vane using piecewise cubic functions in three segments to satisfy the given geometric constraints. The optimization results indicated that the nozzle discharge coefficient increased when the second and third segments were positioned closer to the throat area. Even simpler shapes, such as a cubic function in one or two segments with less smooth connections between the segments, were tested for comparison. Although the simplest shape using one segment yielded the best performance, all considered shapes were proposed as candidates for the optimal shape in the general design of the pre-swirl nozzle vane.