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 two-stage low pressure turbine with integrated 3D airfoil and endwall contouring is tested. The experimental data taken in the altitude test-facility study the effect of high incidence in off-design 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 off-design high-incidence conditions lead to a different flow-field 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 three-dimensional flow-field. 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 flow-field.