A TIME-DOMAIN METHOD TO PREDICT SHIP MOTIONS IN OBLIQUE SEAS AT FORWARD SPEEDS  

作　　者：D. X. ZhuChina Ship Scientific Research Center,P. O. Box 116,Wuxi 214082,P. R. ChinaM. KatoryDept. of Civil & Structural Engineering, The Hong Kong Polytechnic University, HongKong, P.R.ChinaB. Q. LIChina Ship Scientific Research Center,P. O. Box 116,Wuxi 214082,P. R. China 

出　　处：《Journal of Hydrodynamics》1997年第4期60-70,共11页水动力学研究与进展B辑（英文版）

摘　　要：Time-domain analysis is used to predict wave loading and motion responses for a ship travelling at a constant speed in regular oblique waves. The combined diffraction and radiation perturbations, caused by the steady forward speed of the ship and her motions , are considered as a distribution of normal velocities on the wetted hull surface. The ship-hull boundary condition is exactly fulfilled by expressing the fluid normal velocities as a finite series in terms of the body geometry and the incident wave potential. As far as the authors are aware, no similar work is published todate.The new theory is applied to predict forces and motions at forward speed for a Wigley ship-hull in head waves and a catamaran-ferry in oblique waves. Predictions are compared with published theoretical and experimental results for the Wigley ship-hull, and the comparison is good. For the catamaran, a self-propelled model is built and tested in the large towing tank and seakeeping basin of the China Ship Scientific Research Centre, Wuxi, China, in order to measure the six-degrees-of-freedom forces, moments and motions at forward speed in waves of different directions. Measurements are compared with predictions, and the comparison is generally good for the longitudinal motions thus verifying the analysis. For the transverse motions, acceptable discrepancies exist due to the non-inclusion in the analysis of rudder forces and viscous damping, and due differences in structural inertia properties between the physical model and the corresponding data used in the analysis. The inclusion of viscous damping in the time domain involves complex analysis and this problem is left to a future research.Time-domain analysis is used to predict wave loading and motion responses for a ship travelling at a constant speed in regular oblique waves. The combined diffraction and radiation perturbations, caused by the steady forward speed of the ship and her motions , are considered as a distribution of normal velocities on the wetted hull surface. The ship-hull boundary condition is exactly fulfilled by expressing the fluid normal velocities as a finite series in terms of the body geometry and the incident wave potential. As far as the authors are aware, no similar work is published todate.The new theory is applied to predict forces and motions at forward speed for a Wigley ship-hull in head waves and a catamaran-ferry in oblique waves. Predictions are compared with published theoretical and experimental results for the Wigley ship-hull, and the comparison is good. For the catamaran, a self-propelled model is built and tested in the large towing tank and seakeeping basin of the China Ship Scientific Research Centre, Wuxi, China, in order to measure the six-degrees-of-freedom forces, moments and motions at forward speed in waves of different directions. Measurements are compared with predictions, and the comparison is generally good for the longitudinal motions thus verifying the analysis. For the transverse motions, acceptable discrepancies exist due to the non-inclusion in the analysis of rudder forces and viscous damping, and due differences in structural inertia properties between the physical model and the corresponding data used in the analysis. The inclusion of viscous damping in the time domain involves complex analysis and this problem is left to a future research.

关 键 词：TIME-DOMAIN ship motion. 

分 类 号：U661[交通运输工程—船舶及航道工程]