三维流线追踪截短偏置超声速尾喷管非设计工况性能分析

Performance analysis of three-dimensional supersonic asymmetrictruncated nozzle under off-design conditions

使用基于最短长度喷管(MLN)设计方法设计的轴对称喷管流场作为基准流场,采用流线追踪技术和基于代理模型多目标优化方法,并进行了非线性截短和偏置,设计出全新的三维流线追踪截短偏置超声速尾喷管。在非设计工况下对其进行了数值模拟,分析并对比了尾喷管在不同的进口和外流的马赫数和压力时其性能与流场结构的变化。外流马赫数和压力的改变对出口流场结构的影响显著,但对喷管内部流场几乎不产生影响;较大的外流压力会导致过膨胀现象,气流自尾喷管出口处向内偏向尾喷管轴向膨胀,尾喷管唇口附近马赫数将会增大。进口马赫数和进口压力增大,尾喷管的推力和俯仰力矩增大,其中进口压力与尾喷管推力升力性能呈近似线性关系,进口压力每增大5000 Pa,尾喷管的推力,升力和俯仰力矩增大8%左右。所做研究揭示了三维截短偏置高超声速尾喷管在非工况情况下工作的性能规律,将对三维非对称高超声速尾喷管的性能分析以及飞行器发动机设计提供参考。

Using axisymmetric nozzle flow field as the reference flow field,and nonlinear truncation and offset was carried out on the nozzle,a new three-dimensional streamline tracking truncated offset hypersonic nozzle was designed by means of streamline tracking and multi-objective surrogated-based optimization method.Numerical simulations were carried out under off-design conditions,and the performance and flow field structure of the nozzle were analyzed and compared under different inlet and outflow Mach and static pressures.The change of outflow Mach number and pressure has a significant effect on the flow field structure at the outlet of the nozzle,but it has little effect on the flow field inside the nozzle.Larger outflow pressure will lead to over-expansion,and the airflow will expand from the outlet of the exhaust nozzle inward toward the axial of the nozzle,and the Mach near the lip of the nozzle will increase.Thus the Mach number near the nozzle lip becomes higher.The inlet Mach number and inlet static pressure increase,and the thrust and pitching moment of the nozzle increase linearly.When the inlet pressure increases by 5000 Pa,the thrust,lift and pitching moment of the nozzle increase by about 8%.This paper reveals the performance of the 3D truncated and offset hypersonic nozzle under off-design conditions,and provides a reference for the performance analysis of the 3D asymmetric hypersonic nozzle and design of aircraft engine.