EXPERIMENTAL RESEARCH ON HYDRODYNAMIC CHARACTER OF AFT SECTION OF UNDERWATER SUPERCAVITATING BODIES

In a cavitation tunnel, a series of experiments were conducted to investigate the hydrodynamic drag, lift and moment character of the aft section of underwater supercavitating bodies at the different supercavity shapes. Hydrodynamic character of the aft section between one degree and zero degree angle of vehicle attack is compared. The investigation shows when the supercavity is closed to the balance, with the development of supercavity, the drag coefficient of the aft section decreases rapidly, while lift coefficient and moment coefficient increase sharply. When the supercavity covers above area of vehicle and the underside is still wetted, drag coefficient decreases slightly, and lift coefficient and moment coefficient increase up to the peak value. When supercavity covers all the vehicle, lift coefficient and moment coefficient decrease sharply, and drag coefficient changes little about zero. The drag reduction range of the aft section at one degree angle of attack is obviously smaller than that at zero degree angle of attack, and the maximal lift coefficient and moment coefficient at one degree angle of attack are much larger.