Aerodynamic Performance Analysis Of Low Pressure Turbine At Low Reynolds Numbers

Low pressure turbine is an important component of the aero-engine, and the multi-stage low pressure turbine integrates advanced aerodynamics and mechanical features. The weight of low pressure turbine accounts for one-third of the total weight of the aero-engine, which is an important part of the total cost. As an important part, the improvement of the performance of the low pressure turbine impacts vitally to the overall performance improvement. Low pressure turbine operates at high altitude at low Reynolds number, which the low Reynolds number condition has a great impact on, and it has a lower efficiency. Under the cruise condition, low pressure turbine works from 0.8×105 to 3.0×105 of Reynolds number, while at the surface of the blade the Reynolds number is even under 105. Then the diffuse behind the blade can cause the boundary layer thicker, which can decrease the performance of the low pressure turbine.This thesis calculates and analyzes the last stage of the low pressure turbine of an aero-engine at different Reynolds numbers, and compares the aerodynamics performances. By the calculations and analyses, it can be seen that the efficiency and the load decreases greatly, the loss increases, the boundary layer gets thicker, and the loss of horseshoe vortex enhances compared with the condition of the one at high Reynolds numbers.The thesis also calculates and analyzes this stage of low pressure turbine at different Mach numbers and different Reynolds numbers. It mainly analyzes some aerodynamics phenomenon, such as the loss of energy, the distribution of the surface of the blade, limited streamline, the interaction in the shock and the boundary layer, and so on. We can see that at the condition of different Mach numbers and different Reynolds numbers, the loss at low Reynolds number increases, and the interactive in the shock and the boundary layer is obviously.The thesis does theory analyses at the problem of how to increase the efficiency of the low pressure turbine, and optimizes the parameters of the stacking law. Through the analyses, we can see that the adoption of bowed blade can decrease the loss effectively.