Parametric optimization of vortex generator configuration for flow control in an intake duct for waterjet propulsion

Vortex generators (VG) are simple miniature devices that suppress flow separation in aeronautical elements. In this study, VG device operation in a submerged flush waterjet inlet was numerically investigated to improve the flow quality entering the jet pump at low Inlet Velocity Ratio (IVR). Steady Reynolds-averaged Navier-Stokes equations are solved using the SST k-& omega; turbulence model and used to simulate the flow field, with the effects of the orientation, angle of attack, height and installation position of VGs thoroughly analyzed. The hydrodynamic performance of the intake duct was assessed over the operational range. The results show that VGs arranged in a divergent configuration better suppress flow separation. The zonal magnitude of the high turbulent kinetic energy on the ramp side was reduced, with the non-uniformity in the pump face plane reduced from 0.41 to 0.26. Excessive angles of attack and VG heights have negative effects. Through parametric studies, VGs were found to have best performance in the target duct with an angle of attack of 400 and a height measuring 20% of the bottom boundary layer thickness. In addition, VGs installed along the keel of a ship can effectively suppress the flow distortion and improve the overall efficiency of the intake duct.