直升机后机身内埋式红外抑制器隐身性能分析

Analysis of stealth properties on IR radiation suppressor embed inside helicopter rear airframe

为了降低直升机的红外辐射特征，针对直升机后机身内埋式的红外抑制器，采用数值模拟的方法较为系统地研究了红外抑制器排气出口形状、旋翼下洗气流速度以及机身蒙皮发射率等因素对红外辐射特性的影响。研究发现：混合管波瓣出口与矩形出口相比，喷流核心区温度大幅度降低，采用波瓣出口混合管，喷流在3—5μm波段的红外辐射强度降低了10％以上；旋翼下洗气流速度的增加，降低了喷流核心区和后机身蒙皮的温度，同时大幅降低了喷流3—5μm波段的红外辐射强度；随着机身蒙皮发射率的减小，机身蒙皮在3—5μm和8～14μm波段的辐射强度大幅降低。结果表明：波瓣出口混合管有利于喷流的强化混合，降低了喷流的温度和辐射强度；旋翼下洗气流速度对降低喷流、蒙皮温度和喷流辐射强度非常有效；机身蒙皮发射率对其表面的红外辐射特性影响非常显著。

In order to reduce the IR radiation characteristic of helicopter, for the IR radiation suppressor embed inside helicopter rear airframe, a series of effects on IR radiation characteristics were studied based on CFD/IR numerical calculations, including shape of mixing duct outlet, rotor downwash velocity and skin emissivity. It was found that the mixing duct with lobed outlet was capable of weakening the temperature of the exhaust plume core region, the IR radiation suppressor with lobed outlet mixing duct could lead to over 10 % decline of IR intensity of the exhaust plume in 3-5 μm band; the increasing in the rotor downwash velocity was benefit to further weakening the temperature of the exhaust plume core region and on the skin of helicopter rear airframe, as well as further decreasing IR intensity of the exhaust plume in 3-5 Ixm band; IR intensity on the skin of helicopter rear airframe was further decreased in 3-5 ~m and 8-14 ~m band accompanying the decline of the skin emissivity. The results show that the duct with＂ lobed outer is capable of enhancing mixing of exhaust plume, decreasing the temperature and IR radiation intensity of exhaust plume; the rotor downwash velocity has great effect on the decreasing of exhaust plume and the skin temperature of helicopter, as well as weakening IR radiation intensity of exhaust plume; the skin emissivity has significant influence on infrared radiation characteristics.