Numerical Investigation of Rotor Aeroacoustics using the Lattice Boltzmann Method

Rotor noise remains a major challenge in the design of future aircraft and urban air mobility (UAM) systems, where public acceptance and certification depend on accurate prediction and mitigation of rotor noise. Experimental studies provide benchmarks for understanding the characteristics of rotor noise, but depending on the experiment’s setup, they are often limited in their ability to reveal the underlying mechanisms leading to noise generation. High-fidelity numerical simulations offer a complementary route to explore these mechanisms in detail. In this work the physics behind the noise generation across various rotor operation conditions are investigated using the commercial <br/>solver PowerFLOW, a Lattice Boltzmann Method hybridised with a Very Large Eddy Simulation model for turbulence modelling (LBM-VLES). Far-field noise is computed with the solid-surface Ffowcs-Williams and Hawkings (FW-H) acoustic analogy from blade surface data, propagated to microphone locations, providing both tonal and broadband noise predictions. Simulation cases are setup to match that of previous experiments carried out at the University of Bristol, for which a plethora of experimental data is available for comparison such as far field acoustic measurements and load data. This comparison will assess/validate the accuracy of LBM predictions, while providing physical insights into dominant mechanisms of noise generation such as blade loading, blade-vortex interactions, and broadband mechanisms e.g. turbulent boundary layer trailing edge noise. The present study forms the first step in a longer-term investigation of rotor aeroacoustics using LBM, with the results contributing to a deeper understanding of rotor noise sources, and the variation in noise generation mechanisms across different geometries/operating conditions