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- Ge, Muye, 1991, et al.
(författare)
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Numerical investigation of pressure pulse predictions for propellers mounted on an inclined shaft
- 2019
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Ingår i: Proceedings of the Sixth International Symposium on Marine Propulsors. - 2414-6129. - 9788876170478 ; 1, s. 284-292
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Konferensbidrag (refereegranskat)abstract
- In the presented study, two high-skew model scale marine propellers were tested in the cavitation tunnel and the induced pressure pulses were measured during the test. Propeller shaft was inclined about 10 degrees to create blade load variations. The cavitation pattern were recorded using high speed videos. The open-source package openFOAM and commercial package Star-ccm+ are used as simulation tools to predict pressure pulses numerically. By using the fully turbulent SST k − ω model, the predicted wetted flow pressure pulse levels agreed well compared to experimental measurements, but together with Schnerr-Sauer cavitation mass transfer model, massive cavitation was predicted which lead to inaccurate pressure pulse predictions. The transition sensitive turbulence model γ − Re θ model is used to study the cases, and simulation results reveal the existence of laminar-transition zone and vortex structures on the propeller blades. Attempts are made to linking correlation-based separation region from the transition model and the cavitation model, and good predictions of cavitation pattern are achieved but the predicted pressure pulses levels are merely improved.
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| 2. |
- Ge, Muye, 1991
(författare)
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Numerical Prediction of Propeller Induced Hull Pressure Pulses
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ship propeller induced pressure pulses is one of the major sources of both onboard noise and vibration as well as underwater radiated noise. The need for accurate pressure pulse prediction is increasing due to rising concerns of environmental impacts and comfort and welfare of passengers and crews. More accurate pressure pulse prediction is needed to be able to reduce the margin between high efficiency propeller design and low pressure pulse propeller design. 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.
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