水下两相冲压喷射发动机性能的数值模拟研究

Numerical study on performance of bubbly water ramjet engine

摘要:

为了对水下两相冲压喷射发动机的性能进行理论研究,分别对扩张段、混合腔及喷管进行分析并建立了物理模型.基于双流体模型,采用变步长的Runge-Kutta法进行了喷管内泡状流计算.综合各部分计算结果求得发动机推力与推进效率.重点研究了混合腔与入口面积比(Am/Ai)、发动机入口面积(Ai)、通气量、航行速度及初始气泡半径对发动机推力及效率的影响.计算结果表明:发动机推力和效率均随着面积比Am/Ai的增大而增大;当Am/Ai保持不变时,推力和效率随入口面积Ai的增大而增大;推力随着通气量、航行速度的增大而增大,效率却随其增大而减小;气泡初始半径增大时,发动机推力及效率同时减小.这将为两相冲压喷射发动机设计提供一定依据.

Abstract:

To predict the performance of bubbly water ramjet propulsion,the physical processes occurring in the diffuser,mixing chamber and nozzle were analyzed.The mathematical models were obtained separately under the restrictions of certain simplifying assumptions.The bubbly nozzle flow was calculated with two-fluid model and variable step-size Runge-Kutta scheme.The influence of area ratios(mixing chamber to inlet area,Am/Ai) ,inlet area A i,air mass flow rate,vessel speed,initial bubble radii and half nozzle converging angle on the thrust and efficiency was investigated by comparing the simulation results.It is indicated that bubbly water ramjet propulsion is more effective for bigger area ratios Am/Ai and bigger inlet area Ai.With the increasing air mass flow rate and vessel speed,the thrust increases,but the efficiency decreases.The increase in half nozzle converging angle and initial bubble radii reduces the ramjet thrust and propulsion efficiency.The results are useful for further investigation of bubbly water ramjet engine.