发动机燃气喷流红外辐射场的数值模拟

在高温流动中热辐射与流场是耦合的,但在发动机燃气喷流流场的温度范围内可以在流场计算中忽略热辐射的影响,于是流场与辐射场的模型方程可解耦.为此提出了模拟飞行器绕流流场红外辐射的解耦模型以及相应的算法.该算法首先采用总变差减小TVD(Total Variation Diminishing)格式对流场进行模拟,再引入有限体积概念,应用所取得的流场参数,在同一组网格上计算流场中的红外辐射特征.以轴对称喷管内N₂,O₂,CO₂,H₂O,CO,HCl,H₂等7组分高度欠膨胀冻结流与均匀绕流干扰流场为算例进行了验证性的模拟计算,并与已有试验和计算数据进行了对比,表明该算法是可靠的,可在较大幅度地降低计算量的情况下给出满足工程需要的结果.

Numerical computations of infrared signatures in exhaust flow fields of jet engines

The thermal radiation field in a high temperature gas flow is coupled with the flow field. However, within the temperature range of the exhaust flow field for a jet engine, the thermal radiation effects can usually be ignored in the computations of the flow field, and the governing equations on the flow field and the radiation field can be decoupled. A decoupling model for computing infrared signatures of the flow fields surrounding the aircraft was proposed. A numerical procedure was constructed by first utilizing TVD(total variation diminishing) scheme to solve the interactive flow field. A finite volume formulation for the spectral intensity was imposed to estimate the total infrared signatures using the computed flow field data over the same set of grids. As a test case for validating the proposed numerical procedure, the infrared signatures in an interaction flow field of a uniformed external flow and a frozen exhaust flow with 7 species, N_2, O_2, CO_2, H_2O, CO, HCl, and H_2, were computed and compared favorably with the available experimental as well as numerical results.