Research And Application Of Key Techniques For Ship Performance Numerical Tank

With upgrade for the level of computer hardware and improvement ofmodern numerical algorithm, the technics of ship numerical performance tankhave become the important mean of ship research and design. Further researchon the key technology of ship numerical performance tank and achievement ofbreakthroughs are of great significance to improve our level of shipdesign and research and international competitiveness, to promote China’sshipbuilding industry development by leaps and bounds.At present, application scope of numerical ship tank method basedon viscous flow CFD theory is becoming more and more extensive.Combination with traditional potential theory in some problems, makes themeans of solution for ship and ocean engineering problem more abundant. Onthe basis of summarizing the recent research development for the simulationmethod and key technique points in the field of speed performance and rollmotion systematically and deeply, an effective method with theorybasis and viscous effects is built which combines results of CFD theory andnumerical investigation and advantage of potential flow method.Ship and propeller interaction is researched by fully RANS method andsliding mesh technique. Self-propulsion point is achieved by adjustingpropeller‘s rotation, and ful-sacled ship performance is predicted based onCFD results and model-ship performance analysis method. Numerical resultsare fairly good agreement with experiment data. A viscous/potential coupledmethod is used to analysis propeller-hull interaction. The effect of actualpropeller in viscous flow is represented by body force. Total velocity in thedamain of propeller plane is obtained by RANS solver. Subtractinduced-propeller velocity from total velocity, then effective velocity is obtained. The effective velocity is renewed to calculate force and inducedvelocity by potential solver, then recycle iteratation.The3D viscous numerical wave tank is established based on the RANSequation, and the regular wave velocity inlet boundary conditions are given,outgoing boundary is used artificial damping zone, which can simulatethe physical pool regular wave. Morever ship diffraction problem with forwardspeed is investigated, and the results of wave loads are predicted. Radiationproblem which includes forced heave and pitch is simulated. Thehydrodynamic added mass and damping coefficients are calculated, andcompared with test date which shows good agreement.The ship rolling motion angle in waves is relatively large, and the rollhydrodynamic is influenced by the hull-form significantly, therefore the rollhydrodynamic characteristics determine the safety and comfort of living inships. The theory research on ship rolling forecast in waves is boundaryelement method based on linear potential, but Viscous and nonlinear effectsplay important roles in ship roll motion. roll damping coefficient determinesthe precision of prediction. In this paper, the dynamic mesh technology isadapted, and the simulations of forced roll and free rolling are carried out.Force and motions are obtained. Roll damping coefficients forthree-dimensional ship are calculated. Comparisons of numerical results ofship roll damping with experimental and potential theoretical ones areconducted. Thus a new numerical method for prediction of rolling damping isestablished, which stands on a theory basis and engineering practical value.