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以轴对称收扩喷管为基础,利用截面曲率控制的方法并结合流量匹配原则,设计生成了不同出口形状的双S弯喷管。采用CFD数值模拟技术获得了6种模型的流场特征及组分浓度分布,在此基础上利用逆向蒙特卡洛方法对其进行了红外辐射特征研究,先后对比了不同模型的后半球红外辐射强度空间分布、探测面辐射亮度分布以及后半球锁定距离空间分布。研究结果表明:双S弯喷管能够有效减缩目标红外信号,出口形状对排气系统红外辐射有一定影响,梯形出口模型的红外辐射强度明显低于矩形出口以及椭圆出口模型,相比基准模型至少使红外辐射峰值减缩70%;随着梯形下底角的减小,其红外辐射强度逐渐降低;在推力损失可接受范围内利用合适的梯形出口能进一步降低排气系统的红外辐射强度。
Based on the axisymmetric convergent and divergent nozzle, a double-S bend nozzle with different outlet shapes was designed by using the method of sectional curvature control and the principle of flow matching. The flow field characteristics and component concentration distribution of six models were obtained by CFD numerical simulation. Based on this, the reverse Monte-Carlo method was used to study the infrared radiation characteristics. The infrared radiation intensities of different models were compared Spatial distribution, radiance distribution of the detection surface and spatial distribution of locking distance of the rear hemisphere. The results show that the double S-bend nozzle can effectively reduce the target infrared signal, and the shape of the outlet affects the infrared radiation of the exhaust system. The infrared radiation intensity of the trapezoidal outlet model is obviously lower than that of the rectangular outlet and the elliptical outlet. Compared with the baseline model, So that the peak value of infrared radiation can be reduced by 70%. With the decrease of trapezoidal bottom angle, the intensity of infrared radiation decreases gradually. Using suitable trapezoidal outlet within acceptable range of thrust loss can further reduce the infrared radiation intensity of the exhaust system.