An unexploited rotational momentum, i.e. swirl, is present in the slipstream of propellers. Stationary vanes, called swirl recovery vanes (SRVs), have been proven to be effective in increasing the propulsive efficiency of propellers. There is however no conclusive answer in literature on the noise effect of SRVs. Additionally, as the propeller slipstream is seen to be highly periodic, it is interesting to study the unsteady effects on the SRVs.

A lattice Boltzmann method is applied to generate time-dependent aerodynamic and aeroacoustic results. The noise is seen to be increased in up- and downstream direction due the SRVs. The thrust generated by the SRVs is seen to be fluctuating due to a sensitivity to the inflow angle. Shortened vanes are investigated to avoid the impingement of the propeller tip vortices, resulting in a substantial reduction in thrust and a minimal effect on the aeroacoustic performance.