冲压发动机风洞引射器引射性能模拟

Simulation study on ejection performance of ramjet engine wind tunnel ejector

蒸汽引射器是冲压发动机试验台用来实现高真空度的重要设备,其工作环境复杂,性能优化较为困难。简化并建立蒸汽引射器的模型,通过Fluent软件对其工作情况进行数值模拟,分析工作状态下引射器内流场变化情况,并利用控制变量法分析引射器中水蒸气含量、工作流体压力、引射流体压力等工况参数对引射器工作能力的影响。通过与试验数据的对比,验证模拟结果的可信度。结果表明:引射流体流量增大时,引射器效率升高;引射流体中水蒸气从0变化到50%时,引射系数由0.45降至0.36。而当工作流体入口压力由1.07 MPa升至1.42 MPa时,引射系数由0.41降低至0.33;引射流体入口压力由12 kPa升至54 kPa时,引射系数由0.12升高至0.43,故在优化设计时应综合2个入口压力的影响。

Steam ejector is an important equipment used in ramjet test-bed to achieve high vacuum.Its working environment is complex and thus its performance optimization is difficult.The model of steam ejector was simplified and established.The working condition of ejector was simulated by Fluent software.The change of flow field in the ejector under working condition was analyzed.The method of control variable was used to analyze the influence of working condition parameters such as water vapor content, working fluid pressure and ejector fluid pressure on ejector s working ability.The reliability of the simulation results was verified by comparing with the experimental data.The results show that the ejector efficiency increases with the increase of the flow rate of the ejector fluid, and the ejection coefficient decreases from 0.45 to 0.36 when the percentage of water vapor in the ejector fluid changes from 0 to 50%.When the inlet pressure of the working fluid rises from 1.07 MPa to 1.42 MPa, the ejection coefficient decreases from 0.41 to 0.33;when the inlet pressure of the ejecting fluid rises from 12 kPa to 54 kPa, the ejection coefficient rises from 0.12 to 0.43.So the influence of the two inlet pressures should be comprehensively considered in the optimization design.