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. @en

Compared with the single propeller, a propeller with Swirl Recovery Vanes (SRV) has great advantages in recovering the residual swirl, which leads to an improvement both in thrust and propulsion efficiency. Based on the preliminary design of the SRV for Fokker F29 propeller, Design of Experiment (DoE) method was employed to optimize and further improve the performance of SRV in the present study. Firstly, orthogonal experiment was adopted to identify the most significant factors for affecting thrust. Secondly, steepest ascent method was used to search for the optimum range of target factors by using climbing experiment and factorial experiment. Finally, center composite experiment was adopted to find the optimal solution. As a result, the thrust of the optimized SRV has increased significantly by 11.78% at the design point, which leads to a 0.66% increment of total efficiency of propeller and SRV propulsion system, and even more increment at low rotation speed (2.10%). Besides, compared with the original SRV, the optimized SRV geometry improves the flow characteristics at the tip region of the vane. The tip vortex and swirl kinetic energy have been weakened distinctly, and the thrust coefficient distribution along the spanwise tends to be more uniform.@en