高焓激波风洞喷管流场非平衡特性研究

摘要

The high enthalpy shock tunnel is an important ground facility for the research of hypersonic flow.However,the expansion process of the high enthalpy flow in the nozzle is a typ-ical flow with thermo non-equilibrium and chemical non-equilibrium,and the characteristic pa-rameters of the free stream flow are difficult to be determined by direct measurement tools.With numerical solving axisymmetric Navier-Stokes equations coupling with two temperature model, the non-equilibrium flow characteristic in a high enthalpy shock tunnel under its typical experi-ment conditions is studied in this paper.The rule of enthalpy to the non-equilibrium characteris-tics is also studied.Results show that the uniform field at the nozzle exit can reach up to 75% of the nozzle exit diameter,which can offer sufficient space for model experiment.The nozzle free stream will be frozen at about 0.4m after the nozzle throat.With the increase of enthalpy from 8.4 to 19.5MJ/kg,the non-equilibrium degree will increase with as enthalpy increases.At the low enthalpy,the increase will be more intense.%高焓激波风洞是开展高超声速流动研究的重要地面模拟设备，但其产生的高焓气流在喷管中的膨胀过程是一种典型的热化学非平衡流动，试验段特征参数通过直接实验测量难以完全确定。本文通过求解耦合双温度模型的轴对称 Navier-Stokes 方程，研究了高焓激波风洞中典型状态下气流的热化学非平衡流动特性，分析了焓值对非平衡特性的影响规律。结果表明，喷管出口自由流均匀区域达到出口截面直径的75％以上，能够为实验提供足够的空间；喷管出口自由流处于热化学非平衡状态，在喷管喉道后约1／5喷管长度处气流即已处于冻结流状态，组分浓度和振动温度随气流流动基本不变；焓值在8．4MJ／kg～19．5MJ／kg 之间变化时，非平衡程度随着焓值的增加而增强，但是低焓值时非平衡程度的增强更加剧烈。