Investigation On Aerodynamics And Heat Transfer Of Turbine Shroud

Turbine tip leakage flow affect the reliability and efficiency of aircraft engine seriously.Shroud with labyrinth seal structure can effectively reduce the leakage flow and vibration,therefore,turbine blades designed with shroud and labyrinth are widely used.Numerical simulation and experimental studies have been conducted in this article to investigate the generation mechanism of the shroud leakage flow and the aerothermal performance of shroud.Firstly,a numerical study on leakage and heat transfer characteristic of shroud without tip jet.This part of study include shroud leakage flow structure,the total pressure loss coefficient of the cascade and the distribution of the shroud heat transfer coefficient.The influence of shroud clearance,pressure ratio and inlet angle on the aerothermal performance were detailed studied.The results showed that the leakage flow forms complex flow structure and leads to total pressure loss downstream the rotor in the area near the casing.The heat transfer coefficient near the first labyrinth and leakage vortexes are higher.The pressure ratio and clearance height are the main factors that influence the leakage and heat transfer characteristic while the inlet angle have little influence on the distribution of the heat transfer coefficient.Then,the leakage coefficient and the distribution of cooling effectiveness of shrouded cascade with tip jet are studied by numerical simulation.The influence of clearance,pressure ratio and blowing ratio are investigated.Finally,an experimental investigation was conducted to study the aerothermal performance of the shroud model.The discharge coefficient,distribution of cooling effectiveness and Nusselt number of the shroud model were studied.The experimental results showed good agreements with numerical results.