Assessment of Numerical Methods for Low Pressure Turbine Tone Noise Prediction

The capability to accurately predict the tone noise of Low Pressure Turbines (LPT) is crucial in designing and optimizing aircraft engine turbofans for low noise emissions. Especially during approach conditions the LPT is an important noise source for commercial aircraft. In this paper, two methodologies for exhaust turbine tone noise analysis are described and validated against an experimental database measured in an acoustic test rig. The first method, a preliminary analysis technique, is suitable during the early design phase; whereas the second methodology is based on a 3D linearized approach which is used in the last steps of the acoustic design. Very good agreement is observed between numerical predictions and measurements for all interactions at approach operating conditions.