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Abstract of Ph.D.Thesis
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Full Manuscript


A surface panel method formulation applied to the analysis of a marine propeller for different wake models and cavitation prediction of hydrofoils are presented in two separate parts (Part I and II). The method is based on Green's theorem which is composed of the combination of dipoles and sources distribution on the body and cavity (in case of partially cavitating hydrofoil) and also, dipole distribution on the trailing vortex wake to represent the potential flow around the propeller and partially cavitating hydrofoil.
In part I, Investigation of three kinds of wake models (linear wake model, deformed wake model based on slip ratio and new wake model based on thrust loading coefficient) for a marine propeller are presented. New wake model based on thrust loading coefficient uses the momentum theory technique in conjunction with iterative procedure to generate the wake model. Using a momentum theory, the ratio of propeller wake radius at the infinite downstream to the blade radius can be obtained. The first solution is obtained based on linear wake model. The iteration process is repeated until the results are converged. The calculated results are in good agreement compared with experimental data and other methods.

The potential surface panel method applied to the analysis of partially cavitating three-dimensional hydrofoil is presented in part II. A type of cavitation that is applied for calculation is sheet cavitation. Using the Green's theorem, the normal dipoles and sources distributions on surfaces of the foil and cavity may constitute the perturbation velocity potential. Kinematic and dynamic boundary conditions are applied on the cavity surface to obtain the source and potential distributions. The cavity thickness is determined by solving partial differential equation through an iterative process until the thickness at the end of cavity at all spanwise locations surpasses a prescribed small value near to zero.
After convergence, the cavity planform and pressure distribution can be calculated. Some of our results are compared with other computational results. Comparison is made for NACA0015 that the present mathod gives a shorter cavity length than the experimental one. The actual lack of experimantal results for other hydrofoils prevents a further complete validation of the three-dimensional process. Therefore, comparison of calculated cavity planform and pressure distributions for other hydrofoils are made with promising insights of other researcher's computational results. The present method marks a prospective object in the development of the cavitation field which will be attracted to the other researchers.

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