Interaction Between Cavitation Bubble and Projectile with Coaxial Concave Tail
摘要
This paper investigates the interaction dynamics and propulsion mechanism of a cavitation bubble and a projectile with a coaxial concave tail employing experimental, numerical, and theoretical approaches. The bubble undergoes near-piston-like pulsations in the concave, which changes the interaction markedly relative to a solid projectile. For the same input energy, the concave-equipped projectile achieves maximum velocities exceeding five times those of its solid counterpart. A theoretical model integrating bubble pulsation dynamics and projectile motion was developed to elucidate the propulsion enhancement mechanism. Theoretical analysis confirms that the concave prolongs expansion and slows the decay of internal pressure, yielding a stronger and more sustained propulsive force. Furthermore, the influences of key governing parameters including equivalent maximum bubble radius Rm, concave length ratio θ, and bubble initiation location σ on propulsion characteristics were systematically investigated. Scaling laws correlating maximum projectile velocity with these governing parameters were derived and validated. Our findings establish the bubble initiation location σ as the key determinant of propulsive efficiency. Control over σ provides a practical means to regulate projectile velocity, opening new possibilities for manipulating bubble-propelled systems.