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Bubble volume and bubble geometry are key parameters that affect the movement and acoustic radiation performance of bubble columns. This paper proposes an image processing method to study the movement and acoustic radiation characteristics of the rising bubbles originating from the combustion of a pyrotechnic composition based on high-speed photography. Results showed that during the rise of bubbles, their shape gradually changed from spherical to irregular, and their rising trajectory presented a curvilinear form. After the rising velocities of the bubbles in the z and x directions were compared, the results revealed that the rising velocity of the bubbles was unstable. The velocity of the rising bubbles in the direction of the z axis was much higher than that of the x axis. Meanwhile, the acceleration of bubble volume decreased first and then increased. This process was repeated; however, the amplitude of increase or decrease was inconsistent, which led to the generation of a certain amount of acoustic radiation effect, and it had a similar trend of change with the acceleration of bubble volume.

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Currently, the supercavitating projectiles mostly rely on experience or experimental results to test the shape of the projectile; however, the cost of the experiment is relatively high, and there is no specific criterion to judge whether the underwater projectile is stable. To solve the aforementioned problems, we study the motion stability and establish motion equations for supercavitating projectiles. Through theoretical analysis and simulation calculations, the optimal center of mass position is designed to optimize the motion performance of underwater supercavitating projectiles. We think this work can provide theoretical support for the optimal design of underwater supercavitating projectiles.

The numerical model of supercavitating flow field was established based on multiphase model, cavitation model, and turbulence model. The model was employed to simulate the supercavitation flow for the supercavitating vehicle with two types of control surfaces: bow rudder and stern rudder. The influence of both control surfaces on the supercavity shape and rudder effectiveness is compared under the different rudder angles (0-12°), and the effectiveness and the influences on supercavities of bow rudder and stern rudder were explored according to the numerical research results. From the research results, the following conclusions can be drawn: (1) the bow rudders have stable rudder effectiveness and available rudder angle, and the bow rudders also have significant influence on supercavities’ shape. (2) By contrast with the bow rudder, stern rudders’ effectiveness is difficult to predict accurately, and the phenomenon of stalling will occur when stern rudders’ rudder angle exceeds 6°; however, there is almost no influence of stern rudders on supercavities. (3) The bow and stern rudders joint control mode must take the influence on supercavities’ shape and the accuracy of control force’s forecasting into account at the same time. The research is helpful to the optimizing of superhigh-speed vehicles and the design of control modes.