Pre-Swirl Stator: Design Target and Arrangement of Geometry
Dr.-Ing. Heinrich Streckwall, Hamburg Ship Model Basin, HSVA, Hamburg, Germany
A pre-swirl stator mounted in front of an open propeller provides a modified inflow at the propeller plane. Our efforts on the arriving tangential flow should finally pay back in a reduced required power. By working on the tangential flow our aim is to eliminate several sources for wasted energy, which include also hub vortex losses. To start the design, one RANS-based calculation is sufficient to obtain the flow at the stator plane. Next a Boundary Element Method (BEM) based model is frequently applied for the proper adjustment of the stator fins. As an advantage of this procedure geometrical changes on the fin system are readily introduced and examined. Due to inherent simplifications the BEM approach reflects the interaction of fins, hull and propeller only qualitatively. Accordingly a final confirmation by a RANS based numerical propulsion simulation or a propulsion test is necessary, whereby the latter should provide possibilities for further fin adjustments.