The Effect Of Upstream Wake On Aerodynamic Performance Of Low Pressure Turbine Blades

With the increase of the ratio of the bypass ratio and thrust ratio of modern civil turbofan aviation engine,high-load low-pressure turbine blades have received more and more attention,but the high loss problem caused by low Reynolds number working environment and high load became more obvious.In the actual work of the low pressure turbine,due to the interference of the wake of upstream blade,it has a great influence on the development of the boundary layer of the downstream blade.Therefore,it is of great significance to study the aerodynamic performance of the low pressure turbine blade for the upstream wake.This article addresses the following issues:For a certain type of high-load low-pressure turbine blade profile,three types of experimental conditions were performed,including no-wake interference condition(fr=0.0),with-wake interference conditions(fr=0.3,0.6),the comparison of negative attack angle condition and negative attack angle effect condition.The parameters such as the distribution of static pressure coefficient on blade and the total pressure loss coefficient of cascade were obtained through experiments,and the influence of the upstream wake on the aerodynamic performance of the low pressure turbine blade was discussed.Using numerical simulation software(Fluent)to simulate the influence of the upstream wake on the aerodynamic performance of the downstream blades under experimental conditions,including steady and un-steady experimental conditions.The details of flow field that could not be detected in experiment were captured.The results show that the upstream wake plays a significant role in suppressing the separation of the boundary layer near the trailing edge of the blade suction surface.For the total pressure loss coefficient of cascade,it decreases as the wake equivalent frequency increases,but the decrease trend is not obvious at higher wake equivalent frequency and higher Reynolds number.For the blade Zweifel coefficient,it increases with the increase of the Reynolds number under on-wake interference condition,but there is an opposite trend under wake interference condition.For the comparison of negative attack angle condition and negative attack angle effect condition,the blade Zweifel coefficient of the wake negative attack angle effect condition is higher than the blade Zweifel coefficient of the corresponding negative attack angle condition.There is a critical equivalent frequency that reduces the total pressure loss coefficient of cascade.The critical equivalent frequency is 0.27 under the experimental conditions of this thesis.