| 1. |
- Han, Kaijia, 1974, et al.
(författare)
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A numerical study of hull/propeller/rudder interaction
- 2008
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Ingår i: Proceedings, 27th Symposium on Naval Hydrodynamics, 5-10 October 2008, Seoul.
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Konferensbidrag (refereegranskat)abstract
- A numerical study of the interaction between the hull, propeller and rudder is presented in this paper. The flow around a ship hull at full scale is first calculated using a RANS solver with a series of systematically generated grids. This grid dependence study is made for the total resistance of the hull and a grid density is chosen. The total resistance of the same ship at four Froude numbers at model scale are computed and compared with experiments. Then self-propulsion tests of the hull and propeller with and without rudder are simulated and compared with measured data. Good agreement is found. By moving the rudder backwards, the effect of the distance between propeller and rudder behind the hull is captured and shows the same tendency as the experiment. Flow fields, such as axial velocity contours at the propeller plane, slipstream deformation, due to the rudder, and limiting streamlines on the surface of rudder and hull are illustrated. Comparisons between two configurations with rudder at different positions are made. It is demonstrated that the present method is promising for evaluating self-propulsion characteristics of hull/propeller/rudder configurations.
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| 2. |
- Han, Kaijia, 1974, et al.
(författare)
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A procedure for optimizing cavitating blades in a given wake
- 2006
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Ingår i: Ship Technology Research. - 0937-7255. ; 53:1, s. 39-52
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Tidskriftsartikel (refereegranskat)abstract
- The blade geometry of a cavitating propeller in a given wake is optimized to maximize propeller efficiency and minimize propeller induced pressure fluctuations. The Keller criterion, the cavity volume and other constraints are considered in the optimization process. Such constraints are cavity area, cavity length and face side pressure and they are switched on separately or simultaneously to investigate their influence on cavitation and efficiency. Optimization is made starting from a near optimum propeller as well as from an off-design propeller. Results indicate that the present optimization technique can yield higher efficiency and lower pressure amplitude with tolerable cavitation for a cavitating propeller in a given wake.
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| 3. |
- Han, Kaijia, 1974, et al.
(författare)
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A RANS study on the interaction between a propeller and a rudder in open water
- 2007
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Ingår i: 10th Numerical Towing Tank Symposium (NuTTS 2007).
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- When designing a ship, it is important to estimate accurately the effects of propeller-rudder interaction, as the rudder behind a propeller and a ship has a great effect both on the propulsive and maneuvering performance. In order to both understand the physical phenomenon and validate the RANS solver SHIPFLOW, the interaction between a propeller and a rudder in open water is qualitatively and quantitatively predicted and validated against experimental data. Furthermore, the propeller slipstream deformation is illustrated and the regain of rotational losses by the rudder is estimated.
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| 4. |
- Han, Kaijia, 1974, et al.
(författare)
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Numerical optimization of a propeller behind a ship hull at full scale
- 2006
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Ingår i: 26th Symposium on Naval Hydrodynamics. ; VOL II, s. P87-98
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A propeller behind a ship hull (the Hamburg test case) at full scale is optimized to minimize the delivered power at a given ship speed by adjusting the geometry and the revolution speed. An uncertainty analysis and a wake validation are made for the CFD (Computational Fluid Dynamics) code SHIPFLOW. The minimum iteration number and grid density were carefully selected to decrease the computation time needed. The optimization is done with a parallel Adaptive Range Genetic Algorithm in the coarse grid and a local optimization starting from the optimized design is performed to check whether it is a local optimal, at least. Then the verification of the optimal propeller for both objective function and constraint in three finer grids is made. To satisfy the constraints in the finer grids, we make a manual correction by adjusting one design variable. At the same time, an automatic optimization starting from the optimum we obtained in the coarse grid is made in the finest grid with a local optimization method, DHC (Dynamic Hill Climbing). The designs by manual correction and automatic optimization are compared. Furthermore, an off-design propeller behind the same ship is also optimized with the same design variables, constraint and objective function. An optimum close to the one obtained in the near-optimum propeller optimization is found. Results indicate that the present optimization procedure can yield lower delivered power for both a near-optimum and an off-design propeller.
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| 5. |
- Larsson, Lars, 1945, et al.
(författare)
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Numerical optimisation of propeller-hull configurations at full scale
- 2006
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Ingår i: Proceedings of the Institute of Marine Engineering, Science and Technology Part A: Journal of Marine Engineering and Technology. - 1476-1548. ; A8
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Tidskriftsartikel (refereegranskat)abstract
- Optimisation of propeller/hull configurations based on the Reynolds-Averaged Navier-Stokes (RANS) equations has been very rare so far, due to the large computational effort required. Virtually no such optimisation has been carried out at full scale, where only a few RANS methods are at all applicable due to stability problems. The present paper introduces a newly developed RANS solver especially designed for stability and this solver is shown to work well at full scale. Through a link to a commonly used propeller analysis code predictions of the viscous flow around the full scale ship with an operating propeller may be made. This is utilized in the work reported here, where the flow codes are introduced into a system for automatic optimisation. It is shown that even well designed propellers may be further improved both in a fixed wake and in the wake behind a fixed hull.
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| 6. |
- Orych, Michal, 1979, et al.
(författare)
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A Surface Capturing Method in the RANS Solver SHIPFLOW
- 2009
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Ingår i: 12th Numerical Towing Tank Symposium.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this study, the SHIPFLOW steady state RANS code is extended to include the computation of free surface flows. A volume-of-fluid (VOF) surface capturing method is used to locate the water-air interface. A void fraction transport equation is introduced to the system of equations and solved in a coupled manner. The finite volume formulation is used and the convective fluxes discretization is basedon the first order Roe type flux difference splitting algorithm. Various higher order corrections were tested, however results from only selected ones are presented here.
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| 7. |
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| 8. |
- Orych, Michal, 1979, et al.
(författare)
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Viscous Free Surface Calculations for the KCS Hull
- 2010
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Ingår i: Gothenburg 2010 - A Workshop on Numerical Ship Hydrodynamics - Proceedings. ; 2
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper describes computations of the flow around the KRISO Container Ship (KCS) with focus on wave pattern predictions. A steady state RANS code with a volume-of-fluid (VOF) free surface capturing method is used. The calculations are performed with block structured grids with H-O topology and around 4 million cells. The results obtained show a satisfactory correlation with the measurements.
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| 9. |
- Regnström, Björn, 1960, et al.
(författare)
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Drag and wake prediction for ships with appendages using an overlapping grid method
- 2006
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Ingår i: 26th Symposium on Naval Hydrodynamics, Rome, Italy, 17-22 September 2006.
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Konferensbidrag (refereegranskat)abstract
- A flexible and robust overlapping structured grid methodis introduced and applied to the computation of the flowaround two ship hulls with appendages. The ships area frigate with sonar dome, bilge keels, propeller shafts,brackets, nozzles and rudder and a hopper-dredger withhead-box, shafts, brackets and nozzle. Results are presentedboth for model and full scale and compared to experimentaldata.
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| 10. |
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