The Effect of Entropy Waves Features on the Indirect Noise Generation within an Aeronautical High-Pressure Turbine Stage

First stages of aeronautical high-pressure turbine are subjected to inlet distortions generated by the combustor systems. Such disturbances, characterized by velocity and temperature fluctuations, are referred to as vorticity and entropy waves and they are convected downstream by the main flow. Such disturbances interact with the turbine stages affecting the stage efficiency, heat exchange and generating noise emissions. This work summarizes a comprehensive numerical campaign on the effect of different Entropy Waves features (i.e. radial position, clocking and swirl direction) on the indirect noise generation of engine-representative high pressure turbine stage tested at the Politecnico di Milano LFM (Laboratory of Fluid Dynamics of Turbomachinery). The numerical campaign is based on URANS CFD simulations with time-varying inlet distortions, carried out with the University of Florence in-house TRAF code. A Discrete Fourier Transform (DFT) based post-processing tool has been used to extract the low frequency entropy wave content to assess indirect noise emissions. The extensive validation of the TRAF code in previous campaigns grants the fidelity of the results in terms of aerodynamic and acoustic quantities. The numerical results provide a deeper insight of the effect of entropy waves features on indirect noise generation. The outcome of the results may be used by the designer to better understand the combustor-turbine interaction, also considering the possible introduction of innovative fuels such as hydrogen or Sustainable Aviation Fuel (SAF).