Description and validation of the ONERA computational method for the prediction of blade-vortex interaction noise

The computational method used at ONERA for the prediction of Blade-Vortex Interaction noise is presented in this paper. The five steps of the computational chain are first described. The calculations are then validated by comparison with two different databases. The first one was obtained in the HART program; in this case, it is shown that the influence of Higher Harmonic Control on wake geometry and radiated noise is well captured. The second one was obtained in the ERATO program, where a passive blade shape optimisation was done: in this case, the calculations succeed in predicting the relative difference in noise levels between the ERATO optimised blade compared to a reference blade, although the wake geometry of the ERATO rotor is not well captured. Finally, strategies to reduce the BVI noise for blades equipped with trailing-edge flaps are proposed.