Numerical Prediction of Propeller Induced Hull Pressure Pulses
Licentiate thesis, 2019
Experimental approaches are used for pressure pulse assessments in the final verification stage where models are produced, but they are limited in early design work. Potential flow based methods have been used for early estimation of pressure pulses, but due to the complexity of the pressure pulse generation mechanisms, including interaction between hull and propeller and various types of cavitation, viscous numerical methods are being developing as a complement to potential flow method and a faster and cheaper alternative of experimental testing. This thesis deals with the numerical prediction of marine propeller induced pressure pulses adapted from typical experimental procedures, including both model scale and full scale marine propellers operating in open-water conditions and behind hull conditions with non-cavitating and cavitating flows. Simulations were conducted using open-source package OpenFOAM and commercial package Star-CCM+ with Reynolds-Averaged Navier-Stokes (RANS) method.
Studied cases show that for propellers in behind conditions, the present RANS approach can provide good accuracy regarding 1 st and 2 nd order BPF (Blade Passing Frequency) hull pressure pulses early in design stage. Higher order BPF pressure pulses were also predicted reasonably well, and different mechanisms inducing higher order BPF pressure pulses, including small tip clearance, transient cavitation appearance and sheet cavitation closure and its interaction with tip vortex cavitation, are outlined in the thesis. For model scale propellers operating under nearly uniform inflows, sheet cavitation is often over-predicted and an improved cavitation mass transfer model is proposed which take laminar separation as an additional inception criteria. Studies regarding mesh resolutions and scaling effects are also included in certain cases.
Chalmers, Mechanics and Maritime Sciences (M2), Marine Technology
Areas of Advance
Fluid Mechanics and Acoustics
Lecture hall EA, EDIT building, Hörsalsvägen 11
Opponent: Professor Poul Andersen, Technical University of Denmark