二元引射喷管高空性能及对无人机红外抑制的数值研究

研究了长/短套管两种结构的二元引射喷管在高空飞行的无人机上的推力特性，以及对无人机3~5μm波段红外辐射特征分布的影响，同时还对比了高空和地面状态下二元引射喷管推力和红外辐射特征.排气系统和无人机的流场、温度场采用商用软件Fluent计算，红外辐射特征采用自主开发的软件（NUAA-IR）进行计算.结果表明:高空状态下二元引射喷管仍可以提高推力特性，但其效果略弱于地面状态；无人机采用二元引射喷管后在大部分探测方向上的红外抑制效果明显，最大降幅为90%；机尾探测方向上长/短套管两种结构的二元引射喷管的红外抑制规律与地面状态不同，短套管二元引射喷管的红外辐射强度大于长套管二元引射喷管，最大增幅为7%. 

Numerical investigation of high altitude performance of 2-D ejector nozzle and infrared supperssion of unmanned aerial vehicle

The thrust characteristics and infrared radiation characteristics in the waveband of 3-5μm of 2-D ejector nozzle with long/short shrouds in the high-flying unmanned aerial vehicle(UAV) were studied.The thrust characteristics and infrared radiation characteristics of 2-D ejector nozzle under the conditions of high-altitude and ground state were compared.The system of the exhaust jet, UAV flow field and temperature field were calculated with commercial software Fluent, and the infrared radiation characteristics were calculated with an infrared analysis software(NUAA-IR) developed independently.The results show that the 2-D ejector nozzle can still improve thrust characteristic under the condition of high-altitude,but the thrust characteristic is a little weaker than that under ground condition.The effect of infrared radiation suppression of 2-D ejector nozzle used by UAV is obvious in most of the detection directions,with the largest decreasing amplitude of 90%.The trend of infrared radiation suppression of these two types of 2-D ejector nozzles in the direction of UAV's tail is different from that under ground condition;the infrared radiation of the 2-D ejector nozzle with short shroud is greater than that with long shroud,and the largest increasing amplitude is 7%.