Abstract: 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. 

Key words: Water ramjet; Underwater movement; Off-design points; Numerical simulation

摘要： 针对水下气液两相冲压发动机非设计工况下运行特性,建立数学模型并开展数值模拟研究,分别分析了通入气体质量流率、航行速度及环境压力变化对发动机性能的影响等,以期全面了解发动机特性,为其设计工作奠定理论基础。计算分析表明:发动机推力随气体质量流率的增大而增大,推进效率随其增大而减小；当实际航行速度大于设计值时,发动机推力略有增大,推进效率在速度为设计值时具有最大值；发动机推力及推进效率均随环境压力增大而略有减小。通过反馈控制调节气体质量流率,可使发动机输出与阻力相近的推力值,使航行体在工作速度范围内的任意速度值下实现匀速航行。 

关键词: 气液两相冲压发动机;水下航行;非设计工况;数值仿真