| 1. |
- TURUNEN, TUOMAS, et al.
(författare)
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Open-water computations of a marine propeller using openfoam
- 2014
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Ingår i: ECFD VI - 6th European Congress on Computational Fluid Dynamics, Barcelona, Spain, 20-25 July 2014. - 9788494284472 ; , s. 1123-1134
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Konferensbidrag (refereegranskat)abstract
- The flow around a marine propeller is studied by means of a RANS-type finite-volume (FV) method. A performance curve in open-water conditions is reproduced computationally and compared to data measured in a cavitation tunnel at Rolls-Royce in Kristinehamn, Sweden. In the computations, both periodic grids with a single propeller blade and grids featuring a full propeller with five blades are used. Two types of full propeller grids are applied. The first one consists of tetrahedral control volumes with prismatic layers near the propeller surface. The second grid type is a hybrid mesh that is a combination of separately meshed hexahedral and tetrahedral grids with an Arbitrary Mesh Interface (AMI) between the two parts. Turbulence is modelled by the two-equation SST k-! model as implemented in OpenFOAM .In steady-state computations, the Moving Reference Frame (MRF) approach is applied to account for the e↵ects due to rotation. In case of transient simulations, moving meshes with the sliding plane approach are utilized and the e↵ect of both numerical and iterative errors due to temporal discretization are studied.This study provides a solid basis for more complicated simulations by providing an understanding of errors caused by grid interfaces and the choice of spatial and temporal discretizations of the governing equations. In particular, the experiences with the AMI methodology will allow the analysis of contra-rotating propellers (CRP) with OpenFOAM. In addition, the robustness of the numerical method is considered in order to be able to produce a usable tool for industrial use.
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| 2. |
- Xia, Liming, et al.
(författare)
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Performance Prediction of a Nozzle Propeller
- 2012
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Ingår i: 29th Symposium on Naval Hydrodynamics, Gothenburg, Sweden, Aug. 2012.
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Konferensbidrag (refereegranskat)abstract
- Nozzle, or ducted, propellers are most commonly used when high efficiency is required at low speed of the vessel. However, normally with a nozzle fitted that accelerates propeller inflow, its blades take a larger risk of cavitation. This paper examines the performance of a nozzle propeller configuration in terms of open water and thrust breakdown characteristics by both experimental and conventional RANS CFD methods. Combining the merits of EFD and CFD, the results reveal some promising features as well as challenges in performance predictions of nozzle propellers.
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| 3. |
- Zhang, Baili, et al.
(författare)
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CFD modeling of propeller tip vortex over large distances
- 2013
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Ingår i: Proceedings of the International Offshore and Polar Engineering Conference. - 1098-6189 .- 1555-1792. - 9781880653999 ; , s. 947-952
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Konferensbidrag (refereegranskat)abstract
- In this paper, a numerical study has been conducted to investigate the evolution of a ship propeller tip vortex over large distance using Reynolds-averaged Navier Stokes (RANS) CFD method. In order to reduce numerical dissipation in tracking the tip vortex, a unique hybrid mesh structure was designed and a vorticity confinement method is also introduced to further enhance the high resolution of the tip vortex.
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| 4. |
- Zhang, B. L., et al.
(författare)
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CFD Modeling of Propeller Tip Vortex over Large Distances
- 2014
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Ingår i: International Journal of Offshore and Polar Engineering. - 1053-5381. ; 24:3, s. 181-183
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a numerical study has been conducted to investigate the evolution of a ship propeller tip vortex over a large distance by using Reynolds-averaged Navier-Stokes (RANS) CFD method. In order to reduce numerical dissipation in tracking the tip vortex, a unique hybrid mesh structure was designed, and a vorticity confinement method was also introduced to further enhance the high resolution of the tip vortex.
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| 5. |
- Zhang, Baili, et al.
(författare)
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Numerical Capture of Wing-tip Vortex Using Vorticity Confinement
- 2012
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Ingår i: 65th Annual Meeting of the APS Division of Fluid Dynamics, November 18–20, 2012, San Diego, California; http://meetings.aps.org/link/BAPS.2012.DFD.A1.6.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Tracking vortices accurately over large distances is very important in many areas of engineering, for instance flow over rotating helicopter blades, ship propeller blades and aircraft wings. However, due to the inherent numerical dissipation in the advection step of flow simulation, current Euler and RANS field solvers tend to damp these vortices too fast. One possible solution to reduce the unphysical decay of these vortices is the application of vorticity confinement methods. In this study, a vorticity confinement term is added to the momentum conservation equations which is a function of the local element size, the vorticity and the gradient of the absolute value of vorticity. The approach has been evaluated by a systematic numerical study on the tip vortex trailing from a rectangular NACA0012 half-wing. The simulated structure and development of the wing-tip vortex agree well with experiments both qualitatively and quantitatively without any adverse effects on the global flow field. It is shown that vorticity confinement can negate the effect of numerical dissipation, leading to a more or less constant vortex strength. This is an approximate method in that genuine viscous diffusion of the vortex is not modeled, but it can be appropriate for vortex dominant flows over short to medium length scales where viscous diffusion can be neglected.
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