宽高比对矩形喷管外尾焰红外辐射的影响

建立了三种不同宽高比矩形喷管的物理模型,采用Fluent6.3软件对三种矩形尾喷管外的三维流场进行了数值模拟,得到尾焰流场的温度、压强和密度等数据,并根据矩形尾喷管外尾焰的特点确立三种矩形尾喷管外尾焰的红外辐射核心计算区域.利用基于洛伦兹线型的统计窄带模型,求出尾焰在窄带l的平均吸收系数；然后采用有限体积法(FVM)求解气体介质中辐射传输方程,最后得到了尾焰的红外辐射的光谱特性与三种矩形喷管尾焰在3～5 μm波段的总强度分布.结果表明:尾焰辐射在2.7 μm和4.3 μm处出现两个辐射峰,并且随着矩形喷管宽高比的增加,尾焰的红外辐射强度大大降低.

Influence of Aspect Ratio on Infrared Radiation of the Exhaust Plume Outside a Rectangular Nozzle

Physical models of three rectangular nozzles with different aspect ratio were established, and the 3-D exterior flow fields of these rectangular nozzles were simulated through numerical method with the software Fluent6.3. Then the data of their flow fields such as temperature, pressure and density and so on were obtained. According to the characteristics of their plumes, the computational areas of infrared radiation were established. Through statistical narrow-band model based on Lorentzian profile, mean absorption coefficients of the plumes in narrow band l were gained. Then radiative transfer equations with gas medium were solved by Finite Volume Method (FVM). Finally, the spectral characteristics and the total intensity distributions in 3～5 μm of those exhaust plumes infrared radiant were acquired. The result improves that two peaks of plume infrared radiant merge in 2.7 μm and 4.3 μm and the infrared radiant of exhaust plume is weakened greatly with the increase of aspect ratio.