一种超声速射流计算方法与实验验证

A Calculation Method and Experimental Verification of Supersonic Jet

关键词:  尾焰  超声速射流  红外辐射  湍动粘性比  可压缩修正

Key words:  Plume  Supersonic jet  Radiation signature  Turbulent viscosity ratio  Compressibility correction

摘要:

高温射流流场计算是尾焰辐射目标特性计算的前提，然而由于缺少可靠实验数据，针对湍流超声速射流的数值模拟多集中于低温射流，高温射流计算与实验的对比工作还很少见。利用 - SST双方程湍流模型，模拟了多个典型超声速射流实验的流场速度与温度分布，通过与实验结果进行对比，建立了一种超声速射流计算方法。首先，通过对比多个低温射流的实验与计算结果，探索了湍流模型中可压缩修正以及来流湍动粘性比对超声速射流计算结果的影响；进而，针对火箭发动机尾焰实验，计算尾焰流场与流场红外辐射，流场辐射计算结果与实验观测结果符合较好，进一步验证了计算方法。最终认为经过可压缩修正的 - SST双方程湍流模型结合湍动粘性比取值30可以作为超声射流计算中较为典型的湍流计算方法。

Abstract:

Calculation of the radiation signature of plume mostly depends on the accurate simulation of the flow field of high temperature jet. Due to lack of reliable experimental data, the numerical study of supersonic turbulent jet is mostly concentrated on the low temperature jets while the simulation of high temperature jets is relatively rare. An in-house developed CFD Code was used to calculate the distribution of velocity and temperature of several jet experiments, by using Menter’s - SST two-equation turbulent model. Based on the numerical study of low temperature jets, a numerical method that is applicable to high temperature jet was established. Firstly, the effects of compressibility correction and various turbulent viscosity ratios were assessed by simulating several low temperature jets. Then, the method was used to simulate a rocket plume experiment, and the numerical method was further verified by comparing the measured and simulated radiance. The simulation and experiment results agree well. This shows that the compressibility corrected - SST two-equation turbulent model with an appropriate turbulent viscosity ratio of 30 is applicable for simulating the plume of aircrafts.