Design and Experimental Validation of Swirl Recovery Vanes for Propeller Propulsion Systems

The momentum transferred to the fluid by a running propeller contains not only the desired axial component but also a rotational component that does not contribute to the propeller thrust. By introducing a set of swirl-recovery vanes (SRVs) downstream of the propeller, part of the rotational flow in the slipstream can be redirected into the streamwise direction, thereby producing extra thrust and enhancing the propulsive efficiency. The current study presents the development, application, and experimental validation of a low-order SRV design tool. The design method combines a short computational time with a detailed vane-shape representation. The procedure is presented together with a test example, consisting of a set of SRVs designed and manufactured for operation with a six-bladed propeller operating at thrust coefficient of CT;P _ 0.32. Results from the computations are subsequently validated by a wind-tunnel experiment with the propeller–SRV model. The SRVs were shown to provide extra thrust at all the considered propeller operating conditions. Because the installation of the SRVs does not lead to an increase in power consumption, it is thus shown that SRVs have the potential to increase the propulsive efficiency during all phases of the flight.