加遮挡罩二元喷管红外辐射特性数值研究

采用计算流体动力学/红外辐射数值计算方法,针对涡扇发动机排气系统,研究了宽高比为3.33的圆转矩形二元喷管尾缘加装遮挡罩以及遮挡罩夹层通道注入冷却气流对红外辐射特性的影响.研究参数范围内的结果表明:遮挡罩内引射或强迫注气的冷却气流对喷流有进一步混合的作用,加装遮挡罩后喷流的红外辐射强度相对于单纯的二元喷管有一定幅度的降低;随着冷却气流流量的增大,二元喷管尾缘内壁面的温度降低效果越显著,有效地利用喷管的引射作用,可以取得良好的红外抑制效果;只有在喷管内壁面红外辐射占主导的探测范围内,加装遮挡罩抑制二元喷管红外辐射的作用才能得到体现. 

Numerical research on infrared radiation characteristics of two-dimension nozzle with shelter covering

Based on CFD/IR(computational fluid dynamics/infrared radiation) numerical calculations,the effects of shelter covering fixed at nozzle trailing edge and cooling air injected inside the shelter covering passage on infrared radiation characteristics of turbofan engine two-dimensional nozzle with aspect ratio 3.33 were investigated.The results based on the present parameters show that,ejected or forced cooling air flow through shelter covering passage enhances further mixing with plume,and suppresses plume infrared radiation in comparison with pure two-dimensional nozzle.As the cooling air massflow increases,the cooling action on nozzle trailing edge is more obvious.Utilizing nozzle ejection effectively could achieve satisfactory infrared radiation suppression.The suppression action on nozzle total infrared radiation with shelter covering is only realized in the detecting azimuth where the infrared radiation from nozzle inner walls is predominant.