Pre-swirl stators design using a coupled BEM-RANSE approach

A design method for pre-swirl stators energy saving devices, using a combined BEM-RANSE approach, is proposed. RANSE calculations, using actuator disks, are employed to provide the required thrust and the effective wake to an unsteady Boundary Element Method through which the rate of revolution of the propeller and its averaged performance in self-propulsion are evaluated. An automatic variation of the pre-swirl geometry, driven by an optimization algorithm that operates on the parameters defining the device, realizes an automatic "try-and-error" process, which is used as a design tool for the maximization of the energy saving effect. Results obtained for different numbers of stator fins show outstanding improvements, up to a reduction of the required shaft power of about 8%.