A Boundary Element Method for the Computation of Unsteady Sheet Cavitation Effects in Marine Propeller Flows

2012 ◽  
Author(s):  
M. Bauer ◽  
M. Abdel-Maksoud
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Marine Propeller ◽  
Sheet Cavitation ◽  
Element Method

Application of a Boundary Element Method in the Prediction of Unsteady Blade Sheet and Developed Tip Vortex Cavitation on Marine Propellers

2004 ◽  
Vol 48 (01) ◽  
pp. 15-30
Author(s):  
Hanseong Lee ◽  
Spyros A. Kinnas
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Pressure Fluctuations ◽  
Ship Hull ◽  
Tip Vortex ◽  
Tip Vortex Cavitation ◽  
Marine Propellers ◽  
Sheet Cavitation ◽  
Numerical Predictions ◽  
Element Method

Most marine propellers operate in nonaxisymmetric inflows, and thus their blades are often subject to an unsteady flow field. In recent years, due to increasing demands for faster and larger displacement ships, the presence of blade sheet and tip vortex cavitation has become very common. Developed tip vortex cavitation, which often appears together with blade sheet cavitation, is known to be one of the main sources of propeller-induced pressure fluctuations on the ship hull. The prediction of developed tip vortex cavity as well as blade sheet cavity is thus quite important in the assessment of the propeller performance and the corresponding pressure fluctuations on the ship hull. A boundary element method is employed to model the fully unsteady blade sheet (partial or supercavitating) and developed tip vortex cavitation on propeller blades. The extent and size of the cavity is determined by satisfying both the dynamic and the kinematic boundary conditions on the cavity surface. The numerical behavior of the method is investigated for a two-dimensional tip vortex cavity, a three-dimensional hydrofoil, and a marine propeller subjected to nonaxisymmetric inflow. Comparisons of numerical predictions with experimental measurements are presented.

Prediction of Sheet Cavitation on Marine Current Turbines With a Boundary Element Method

2012 ◽  
Author(s):  
J. Baltazar ◽  
J. A. C. Falcão de Campos
Keyword(s):  
Boundary Element Method ◽  
Boundary Conditions ◽  
Boundary Element ◽  
Design Stage ◽  
Sheet Cavitation ◽  
Operation Conditions ◽  
Marine Current Turbine ◽  
Marine Current ◽  
Current Turbine ◽  
Element Method

For marine current turbines under certain operation conditions cavitation on the blades may occur. Therefore, it is important from the design stage of such systems to be able to predict the presence and extent of cavitation on the blades. In this paper a boundary element method for the prediction of sheet cavitation of a horizontal axis marine current turbine is presented. The boundary element method is based on a low-order potential formulation. Dipoles and sources are placed on the rigid body surfaces either on the wetted part and beneath the cavities. Kinematic boundary conditions are applied on the wetted surfaces and kinematic and dynamic boundary conditions are applied on the surface of the cavities. The blade wakes are modeled with an empirical formulation. The method is applied to analyze a marine current turbine in steady flow conditions and results are compared with the cavitation observations available in the literature.

Propeller Sheet Cavitation Predictions Using a Panel Method

1999 ◽  
Vol 121 (2) ◽  
pp. 282-288 ◽  
Author(s):  
A. C. Mueller ◽  
S. A. Kinnas
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Panel Method ◽  
Time Dependent ◽  
Variable Pressure ◽  
Water Tunnel ◽  
Sheet Cavitation ◽  
Pressure Water ◽  
Element Method ◽  
Blade Geometry

A boundary element method is used to predict the time-dependent cavitation on a propeller subject to nonaxisymmetric inflow. The convergence of the method is studied. The predicted cavities agree well with those observed in CAPREX, an experiment performed at MIT’s variable pressure water tunnel. The method is modified so that prediction of cavities detaching at mid-chord regions is possible. An algorithm for predicting the cavity detachment location on the blade is described and applied on a blade geometry which exhibits mid-chord cavitation.

A BEM for the Prediction of Unsteady Midchord Face and/or Back Propeller Cavitation

2001 ◽  
Vol 123 (2) ◽  
pp. 311-319 ◽  
Author(s):  
Yin L. Young ◽  
Spyros A. Kinnas
Keyword(s):  
Numerical Analysis ◽  
Boundary Element Method ◽  
Numerical Method ◽  
Boundary Element ◽  
Present Method ◽  
Sheet Cavitation ◽  
Marine Vehicles ◽  
The Face ◽  
Element Method

A boundary element method (BEM) is used for the numerical analysis of sheet cavitation on a propeller subjected to the non-axisymmetric wakes of marine vehicles. This method is extended in order to treat mixed partial and supercavity patterns on both the face and back of the blades with searched cavity detachment. The convergence of the method is studied. The predicted cavity shapes and forces by the present method agree well with experiments and with those predicted by another numerical method.

scholarly journals Optimal design of hydrofoil and marine propeller using micro-genetic algorithm (μGA)

1970 ◽  
Vol 1 (1) ◽  
pp. 47-61 ◽  
Author(s):  
Md Mashud Karim ◽  
K Suzuki ◽  
H Kai
Keyword(s):  
Genetic Algorithm ◽  
Boundary Element Method ◽  
Design Optimization ◽  
Boundary Element ◽  
Population Size ◽  
Design Parameters ◽  
Marine Propeller ◽  
Design Constraints ◽  
Micro Genetic Algorithm ◽  
Element Method

This paper presents results from the application of the genetic algorithm (GA) technique to the design optimization of hydrofoil and marine propeller incorporating potential based boundary element method (BEM). Although, larger population size as implemented by simple genetic algorithm (SGA) could find the optimal individual after a fewer number of generations than smaller population size, it is penalized by a longer amount of time to evaluate fitness in every generation. An investigation is, therefore, conducted in this research to implement micro genetic algorithm (μGA) with a very small population, and with simple genetic parameters, in order to achieve faster convergence to better solution from generation to generation. The technique is applied here to optimize hydrofoils of different plan forms, e.g., rectangular, elliptical, trapezoidal etc. Firstly, the hydrofoil design parameters, such as, angle of incidence, maximum thickness and camber ratios, aspect ratio, taper ratio, angle of sweep etc. are initialized randomly and the generated hydrofoil is analyzed by potential based boundary element method. GA then updates the design parameters over generation after generation and finally, finds an improved hydrofoil of maximum lift-drag ratio or minimum drag coefficient satisfying some design constraints. An improved blade or hydrofoil section is also designed by GA satisfying some design constraints. Finally, the technique is applied to the optimum design of marine propeller. In this study, μGA is found useful and prospective tool for the design optimization of hydrofoil and marine propeller due to its faster convergence. Keywords: Genetic algorithm, boundary element method, hydrofoil, propeller, design optimization  doi: 10.3329/jname.v1i1.2038 Journal of Naval Architecture and Marine Engineering 1(2004) 47-61

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