Numerical Study on Acoustic Phenomena in Cavities for Aero-engine Applications

Abstract: For about seventy years, noise generated by grazing flow past a cavity has been thoroughly studied. Yet, a coherent theory that describes such phenomena is missing. Lately, this phenomena started to be investigated in bleeding systems of aero-engines. The present work, within the CARE (Cavity Acoustics and Rossiter modEs) program, aims at identifying potential resonances and excitations which could lead to a failure of the components in the LPC (Low Pressure Compressor). Specifically, the purpose is to validate the experimental results derived at KTH Heat and Power Technology department. After a literature review and turbulence model study, the wind tunnel and the cavity are analyzed. Steady state simulations are carried concerning the wind tunnel, and different approaches are followed in order to match the numerical results with the experimental ones. Imposing a total pressure profile proved to be the most effective tool to match experimental data, nonetheless a more detailed analysis concerning the turbulence model is required. The velocity profile was then used for the 2D unsteady simulations, performed on the cavity section only. After defining the setup, simulations are carried over all the operating points, ranging from M = 0.3 to M = 0.8. Although the use of a simplified model, a good agreement is found with the experimental results in terms of frequency. Matching the amplitude is still a difficult task, and is left as a future work, as well as 3D cavity simulations.