Analysis of off-design performance for bubbly water ramjet

To predict the off-design performance of bubbly water ramjet, the mathematical models were constructed under some assumptions. The thrust and propulsion efficiency were obtained by numerical simulation. The influences of gas mass flow rate, ship velocity and ambient pressure on the performance were emphatically investigated for a comprehensive understanding of bubbly water ramjet. Results indicate that the thrust increases with increasing gas mass flow rate, but the efficiency decreases. When the ship velocity is higher than the design value, the thrust is higher. However, the maximum efficiency is obtained at the design ship velocity. With increasing ambient pressure, both the thrust and propulsion efficiency decrease. By means of regulating the gas mass flow rate with feedback, it can drive the ramjet output the thrust close to the drag of the vehicle, and then the uniform navigation is achieved at arbitrary velocity in the range of the work speed.