二元激波矢量喷管矢量性能敏感性分析

Sensitivity analysis of vector performance of two⁃dimensional shock vector control nozzle

流体推力矢量技术因其响应快、重量轻、隐身性能好等优势被视为极低可探测布局飞行器发展的关键技术。目前针对流体推力矢量喷管性能的研究主要集中在单变量研究,开展流体推力矢量喷管多变量敏感性分析,有助于明确影响喷管矢量性能的关键参数,指导流体推力矢量喷管设计。基于非嵌入多项式混沌的敏感性分析方法开展了二元激波矢量喷管不同目标对外流马赫数、射流位置、射流角度、喷管落压比(NPR)、二次流压比(SPRt)、主流温比、次流温比共7个设计变量的全局敏感性及相关性分析研究。结果表明:矢量角和矢量效率对射流位置敏感性显著,推力系数对NPR、外流马赫数、二次流压比的敏感性较强,二次流流量比对NPR、SPRt较敏感,主流及次流总温与环境温度的比值对矢量性能的贡献主要体现在二次流流量比中。矢量角和二次流流量比的提升均导致推力损失,又以二次流流量比影响最大。外流马赫数的增大改变了喷管的实际压比,降低了喷管的矢量性能。二次流位置靠近喉道时,射流前分离延伸至喉道,射流后分离在大NPR下发生再附,喷管气动型面变化导致矢量性能下降,严重时发生矢量角反向。激波矢量喷管设计时应使射流位置靠近喷管出口,通过调整射流角度使喷管内弓形激波在给定NPR、SPRt下发展至喷管出口附近,从而在不增加二次流流量比的情况下提升矢量性能。合理的参数组合可以缓解外流马赫数增大对喷管矢量性能的负面影响,且可在不增大二次流流量比的情况下提升喷管矢量性能。

Fluid thrust vectoring technology is regarded as a key technology for the development of very low detect⁃able vehicles because of its advantages such as fast response,light weight and good stealth performance.The cur⁃rent research on the performance of fluid thrust vectoring nozzles is mainly focused on univariate studies.Multivariate sensitivity analysis of fluid thrust vectoring nozzles is carried out to help clarify the key parameters affecting the nozzle vectoring performance,and guide the design of fluid thrust vectoring nozzles.The sensitivity analysis method based on non-intrusive polynomial chaos was carried out to investigate the global sensitivity analysis of seven design vari⁃ables such as Mach number of outflow,jet position,jet angle,Nozzle Pressure Ratio(NPR)and correlation analysis for different targets of the two-dimensional Shock Vector Control(SVC)nozzle.The results show that vector angle and vector efficiency are significantly sensitive to jet position;thrust coefficient is more sensitive to NPR,outflow Mach number,secondary flow pressure ratio(the ratio of total secondary flow pressure to ambient pressure SPRt).The re⁃sults also show that secondary flow ratio is more sensitive to NPR,and the contribution of ratio of total mainstream and secondary flow temperature to ambient temperature to the vector performance is expressed mainly in the secondary flow ratio.The increase of both vector angle and secondary flow ratio leads to thrust loss,and the secondary flow ratio has the greatest impact.The increase in outflow Mach number changes the actual pressure ratio of the nozzle and re⁃duces the nozzle vectoring performance.When the position of the secondary flow is close to the throat,the separation before the jet extends to the throat,and the separation after the jet reattaches under the large NPR.The change of the nozzle aerodynamic profile results in the decline of the vector performance,and in serious cases,the vector angle re⁃versal occurs.The SVC nozzle should be designed so that the jet is positioned close to the nozzle outlet and the oblique shock wave in the nozzle is adjusted to develop near the nozzle outlet for a given NPR and SPRt,thus im⁃proves the vector performance without increasing the secondary flow ratio.A reasonable combination of parameters can mitigate the negative impact of increasing outflow Mach number on nozzle vector performance,and can improve nozzle vector performance without increasing the secondary flow ratio.