A Low Pressure Turbine at Extreme Off Design Operation

Abstract

In a cooperative project between the Institute of Aircraft Propulsion Systems and MTU Aero Engines GmbH, a twostage low pressure turbine with integrated 3D airfoil and endwall contouring is tested. The experimental data taken in the altitude testfacility study the effect of high incidence in offdesign operation. Steady measurements are covering a wide range of Reynolds numbers between 40,000 and 180,000. The results are compared with steady multistage CFD predictions with a focus on the stator rows. A first unsteady simulation is taken into account as well. The CFD simulations include leakage flow paths with disk cavities modeled. Compared to design operation the extreme offdesign highincidence conditions lead to a different flowfield Reynolds number sensitivity. Airfoil lift data reveals changing incidence with Reynolds number of the second stage. Increased leading edge loading of the second vane indicates a strong cross channel pressure gradient in the second stage leading to larger secondary flow regions and a more threedimensional flowfield. Global characteristics and area traverse data of the second vane are discussed. The unsteady CFD approach indicates improvement in the numerical prediction of the predominating flowfield.