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Determination of Hydrodynamic and Aerodynamic Coefficients and Longitudinal Dynamic Equation of a High Speed Catamaran with Commercial Softwares

Motiallah, Arash | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47526 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Kazemzadeh Hannani, Siamak; Seif, Mohammad Saeed
  7. Abstract:
  8. In recent years design and manufacturing of high speed marine vessels has been developed. to estimate and control dynamics of these vessels the dynamic equation is needed.The aim of this research is Determination of hydrodynamic and aerodynamic coefficients and longitudinal dynamic equation of a high speed catamaran wich is a kind of AAMV. There are three ways to determine these coefficients. Analytical method which is usually not applicable for industrial problems, Experimental method which is too expensive and numerical method which have two parts. The first is softwares that analyse the flow with assumption that the fluid is inviscid and second softwares which solve the full Navier-Stokes equation for both viscous and inviscid fluids. The last method has been used for the first time, in this thesis to determine the hydrodynamic coefficients for a racing catamaran. in order to do that, Ansys Design Modeler, Ansys Meshing and CFX will be used. At first in two steps the numerical method used to determine hydrodynamic coefficients will be validated by comparing the numerical results with experimental results in litreture and results extracted from towing tank model test. Then hydrodynamic coefficients in various frequencies for a real racing catamaran will be determined by numerical method. Then numerical method used to determine aerodynamic coefficients will be validated by comparing numerical results by experimental results in literature and after that the aerodynamic coefficients for that racing catamaran will be determined. Then order of magnitude of hydrodynamic and aerodynamic coefficients will be compared with each other and then by combining them, the longitudinal dynamic equation of the racing catamaran wil be determined. Then for evaluating precision of the dynamic model used in this research, results of analyzing motions of a racing catamaran in wave with this model will be compared with the results of another dynamic model in literature. Then dynamic stability of the racing catamaran will be evaluated and the ratio of aerodynamic lift of airfoil-which is placed between the hulls of the catamaran- to total weight of the vessel in different speeds will be determined
  9. Keywords:
  10. Model Test ; Numerical Method ; Hydrodynamic Coefficients ; Aerodynamic Coefficient ; High Speed Craft ; Longitudinal Dynamic ; Catamaran Boat

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