A series of water tunnel model tests have been carried out to study the hydrodynamic characteristic of typical supercavitating vehicles. By ventilation, different lengths of supercavities were generated around the supercavitating vehicle model, inside which a three-component balance was mounted to obtain the forces and moment of the model. By increasing the angle of attack step by step, the hydrodynamic characteristic of the model were obtained at different cavitation numbers. By experimental data analysis, a 'critical angle of attack', which is quite small and related with the slenderness ratio of supercavitating vehicles, were found to govern the hydrodynamic characteristic of supercavitating vehicles: (1) Within this critical angle of attack, the pitching moment curve has a negative or zero slope, for the pressure center lies behind the center of mass, which indicates the static stability of the model. (2) Beyond the critical angle of attack, the pitching moment curve takes a positive slope, which means it is static unstable. (3) The critical angle of attack increases with the reduction of slenderness ratio. (4) When the supercavity closes behind the vehicle, there must be a range of attack angle, in which the pitching moment keeps as zero. That means the aft body of the supercavitating vehicle would sway freely without any damping force, which will be unexpected for supercavitating vehicle design. (5) Besides, the slope of lift curve at supercavitating status is higher than the slope without cavitation. These hydrodynamic characteristic of supercavitating vehicles presented here layout a basis for shape design and motion control of supercavitating vehicles.
Experimental studies on hydrodynamic characteristic of supercavitating vehicles
2012
6 Seiten, 11 Bilder, 4 Quellen
Conference paper
Storage medium
English
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