Study Of Film Cooling Characteristics Influenced By Segmented Swirl Structure

With the development of gas turbine technology,the inlet gas temperature of the turbine has far exceeded the tolerable temperature of the blades and other hot-end components,and the introduction of cooling technology has made it possible to further increase the gas temperature.Therefore,by changing the cooling structure and aerodynamic parameters to increase the coverage area of cold air and improve the efficiency of film cooling has become an important scientific research topic.This article summarizes and analyzes the existing film hole structure,and innovatively proposes the segmented swirl structure.The Segmented swirl structure proposed in this paper is a structure in which a jet column is added between the cold air cavity and the film hole on the basis of the ordinary cylindrical film hole.In order to verify the effectiveness of the segmented swirl structure in improving the film cooling efficiency,this paper first conducts calculation and analysis on a flat plate under four blowing ratio conditions.And analyze the air-conditioning flow structure.The segmented swirl structure increases the average film cooling efficiency by 16.9%,48.9% and33.8% when the blowing ratio M is 1.0,1.5 and 2.0,respectively,while the segmented swirl structure changes the velocity distribution of the cold air in the film pores Become the key to improving cooling efficiency.Further calculations show that the change of the geometric parameter of the jet column length will also affect the film cooling efficiency.Analyze the cooling efficiency improvement effect and the mechanism of eliminating the kidney-shaped vortex pair under the conditions of different blowing ratios after the combination of the composite angle and the segmented swirl structure.The research results show that the 40° compound angle segmented swirl structure has an average film cooling efficiency of 311.1% higher than that of the ordinary cylindrical hole structure when the blowing ratio is 2.0.After the composite angular segmented swirl structure,a part of the cold air jet is scattered and spread on the wall,and the other part is swirling at the top to isolate the upper main flow from the lower cooling air film.There is a complicated flow structure in the cascade channel,resulting in a slight difference between the cooling effect and the flat structure.Therefore,the effect of the segmented swirl structure on the endwall and pressure surface of the inlet guide vane is further verified.The verification results show that the segmented swirl structure has an enhanced ability to suppress the secondary flow of the endwall,thereby completing the coverage of the corner area of the endwall.At the same time,the introduction of the segmented swirl structure at the endwall improves the film cooling efficiency.When the blowing ratio is 2.0,the composite angular segmented swirl structure has improved film cooling efficiency compared with the ordinary cylindrical hole structure and the ordinary composite angular structure.20.8% and 49.4%;at the pressure surface,the segmented swirl structure has little effect on the cooling efficiency when the blowing ratio is low.However,as the blowing ratio increases,the cooling efficiency improvement effect begins to gradually appear.When the blowing ratio is 2.0,the film cooling efficiency of the segmented swirl structure is increased by 68.3% compared with that of the cylindrical hole structure.