Quasi-compact model for accurate noise prediction of complex rotor configurations
Francesco Caccia, L. Galimberti, Luca Abergo, Alberto Savino, Alex Zanotti, Matteo Parsani, Alberto Guardone
Abstract
The design of urban air mobility systems requires fast yet accurate aerodynamic and acoustic analyses of propeller interactions. Low-fidelity solvers relying on compact F1A formulations are commonly used, but the compact acoustic assumption does not hold for loading noise produced by unsteady inflows. This study introduces a quasi-compact acoustic model applied to isolated and tandem interacting propellers comparing its performance against other hybrid solvers. The quasi-compact model propagates the local chord-wise and span-wise pressure jump distribution computed with a non-linear vortex-lattice aerodynamic solution to far-field observers. Compact models simplify this by using the span-wise distribution only. Reference solutions are generated by propagating high-fidelity CFD pressure fields to far-field observers using the same Ffowcs Williams-Hawkings solver. Results demonstrate that the compact formulation achieves convergence only for isolated propellers, whereas the quasi-compact formulation can provide converged solutions also with rotor-rotor interactions and compares better with the reference high-fidelity data.