Study on Cooling Characteristics of an Internal Cooling Structure With a Sloping Sheet for Gas Turbine Blade

Abstract

This study presents a cooling structure with a sloping sheet to improve the internal cooling of gas turbine blades, inspired by the concept of aircraft wing tip vortex. In this paper, the numerical simulation for the sloping sheet cooling structure has been carried out, which takes into account the heat conduction of the metallic material and the heat transfer of the external high temperature flow field. The results indicate that the structure utilizes the pressure difference between two sides of the sloping sheet to produce a strong vortex pair. The vortexes are led to the inner wall surface of the turbine blade by the downwash. Thanks to such a strong pair vortex, the high temperature air close to the inner wall is quickly blown out and the low temperature coolant is induced to impact on the internal surface, thus achieving an efficient cooling effect. Due to the strong vortex strength and the same vortex vector along the coolant flows, the pair vortex will travel a long distance in the cooling channel, and cool larger areas of the inner wall surface. According to the calculation results, such structure can make the overall temperature of the solid region decreased by 40K as compared to the smooth channel. The sloping sheet cooling structure can reduce the total pressure loss by 63% as compared to the array of pin fins which achieve the same cooling effect. Furthermore, the influence of the sloping sheet’s inclination angle, length and width on the cooling characteristics has also been studied. Through the strength analysis by FEM method, the maximum von Mises stress is 21.9 MPa and it verifies that the sloping sheet can work securely and firmly.