Study On Film Cooling Characteristics Of Hole And Slot Structure Of High Pressure Turbine Blade

The high-pressure turbine is an important part of the core engine of the aviation gas turbine.The leakage flow of the turbine tip clearance causes internal flow loss and the turbine stage efficiency decreases.The reattachment of the high temperature leakage flow at the top of the blade tip will also result in a high intensity thermal load on the blade tip,which is highly susceptible to ablation.Research on the film cooling characteristics of turbine blades is of great significance for improving the performance and reliability life of aviation gas turbines and promoting the development of aviation industry in China.In this paper,the numerical simulation method is used to study the film cooling characteristics of a high-pressure turbine blade slot structure,in order to provide reference for the future design of the turbine blade top film cooling structure.The effects of film cooling hole row position,groove depth and relative rotational speed of the end wall on the tip leakage loss and film cooling characteristics under transonic conditions are studied.The results show that the viscous force of the end wall works on the gap flow,changes the reverse vortex pair after the cooling flow hole,and winds up the scraping vortex in the groove,which reduces the leakage flow at the tip of the blade.The analysis found that the cooling hole row position has an influence on the tip leakage flow along the axial chord length distribution and the groove high heat transfer coefficient region distribution,but has little effect on the total tip leakage flow rate and the groove average heat transfer coefficient.At the same time,the influence of the tip leakage flow rate,wall heat transfer coefficient and film cooling efficiency on the groove depth and relative rotational speed is also summarized.In order to further optimize the structure of the tip hole groove,a new type of auxiliary rib and auxiliary rib impact groove tip are designed on the top of the groove tip.The effects of auxiliary rib and the auxiliary rib impact position,quantity and depth on the tip leakage loss,heat transfer performance and film cooling characteristics are studied.The results show that the auxiliary rib can suppress the pressure gradient at the front edge of the groove,increase the mixing intensity of the leakage flow,and reduce the total pressure loss at the tip of the groove.The greater the depth of the groove,the stronger the suppression effect of the auxiliary rib and the auxiliary rib impact groove on the total pressure loss,but the auxiliary rib also suppresses the dispersion of the tip cooling airflow under the original groove pressure gradient.Under the same conditions,the total pressure loss of the cooling tip of the double rib impact groove is the smallest,the average heat transfer coefficient of the wall of the cooling tip of the trailing edge rib groove is small,and the average air film cooling efficiency of the wall is large.