Experimental investigation of the underwater ventilated tail cavity at different angles of attack

The research on the structure and dynamic evolution of ventilated tail cavity is an important basis for designing the tail structure of an underwater vehicle. In this paper, through water tunnel experiments, the characteristics of the ventilated tail cavity at different angles of attack α are studied. Using a high-speed camera and pressure measurement system, the transient evolution characteristics of the tail cavity under different Froude numbers Fr and ventilation flow coefficient C_Qv are obtained. The results show that: under the influence of Fr and C_Qv, the underwater ventilating tail cavity mainly includes four forms: foam cavity (FC), intact cavity (IC), partially broken cavity (PBC), and pulsating foam cavity (PFC); For the intact cavity of the vehicle with the angle attack, the upstream cavity is more stable and long, and more likely to have the re-entrant jet closure. However, the downstream cavity is more broken and isolated, and this phenomenon alleviates as C_Qv or Fr number increases; For the intact cavity, with C_Qv or Fr number increasing, the vehicle bottom pressure fluctuation increases, and the influence of gravity on the vehicle bottom pressure fluctuation is smaller than that of gas-liquid shear on the bottom pressure fluctuation; The energy provided by jet under the 4° attack angle vehicle is lower than that under the 0° attack angle vehicle.