随着红外探测技术的不断发展，给飞行器的安全带来了巨大的威胁，飞行器的红外辐射主要来自于发动机羽流。发动机羽流是未充分燃烧的推进剂与周围大气进行掺混、复燃形成的高温、高速气体，其中主要成分（CO₂、H₂O、CO）能在2-5 μm中红外波段产生强烈的红外辐射。探测系统能根据羽流辐射特性进行目标识别、预警、跟踪和拦截，对目标的生存造成了很大的威胁，提高目标的隐身性能具有非常重要的现实意义。针对于羽流的红外辐射特性，提出通过喷注气体介质加强羽流与环境气体的混合、降低羽流的温度、利用喷注气体的自吸收效应来抑制羽流的红外辐射。

首先建立了羽流的流场和辐射传输计算模型。在研究过程求解轴对称Navier-Stokes方程获得羽流的温度、压力、组分分布等参数，基于NASA-SP-3080数据库采用单线组模型，计算中考虑碰撞展宽效应和多普勒展宽效应来求解各组分的辐射参数，利用视在光线法求解辐射传输方程。根据本文建立的计算模型，对实验数据进行对比，验证了方法的正确性。

接着研究喷注气体CO₂/H₂O/N₂对羽流流动特性和红外辐射特性的影响。本文选择了CO₂、H₂O和N₂作为喷注气体来分析对羽流流动和红外辐射的影响，CO₂和H₂O都是羽流中重要的辐射介质，CO₂在2.7 μm波段、4.3 μm波段有吸收峰，H₂O在2.7 μm波段附近有吸收峰，N₂作为双原子分子缺乏恒定偶极矩在红外区活动较少，选择N₂作为喷注气体主要是作为对照组。在相同的计算模型中，分析了喷注气体CO₂、H₂O和N₂对流场的组分、温度、速度的影响，并据此计算羽流的光谱辐射特性变化规律。

飞行器处于不同的工作条件时外界的环境和飞行速度会发生较大变化。为此，研究了在不同飞行高度和来流马赫数时羽流的流动及红外辐射特征。在此基础上喷注CO₂气体，研究喷注气体对羽流的流动和红外抑制作用。

在地面开展喷注气体对火焰红外辐射测量试验，选择燃烧组分与羽流组分相似的乙炔-纯氧火焰作为探测目标，利用中波红外探测系统测试喷CO₂/N₂对乙炔-纯氧火焰红外辐射的影响。

With the continuous development of infrared detection technology, aircraft safety has been greatly threatened by the infrared radiation emitted from the plumes. The engine plume is a high-temperature, high-speed gas formed by the mixing and reignition of unburned propellant with the surrounding atmosphere. The main components (CO₂, H₂O, CO) can produce strong infrared radiation in the 2-5 μm infrared band. Detection systems can identify, warn, track, and intercept targets based on the plume radiation characteristics, posing a significant threat to target survival. Improving target stealth performance is of great practical significance. This paper proposes suppressing plume infrared radiation by enhancing the mixing of plumes and environmental gases, reducing plume temperature, and self-absorption effect of jet injection medium.

First, a flow field and radiation transmission calculation model of the plume is established. In the research process, the temperature, pressure, and composition distribution of the plume were obtained by solving the axisymmetric Navier-Stokes equations. Then, based on the NASA-SP-3080 database, a single line group model was used to consider collisional broadening and Doppler broadening effects to calculate the radiation parameters of each component. The radiative transfer equation was solved using the line of sight method. Based on the calculation model established in this research, experimental data are compared to verify the correctness of the method.

Next, the effects of jet injection gas CO₂/N₂/H₂O on plume flow characteristics and infrared radiation characteristics are studied. CO₂ and H₂O are important radiative media in the plume. CO₂ has absorption peaks in the 2.7 μm and 4.3 μm bands, while H₂O has an absorption peak near the 2.7 μm band. N₂, as a diatomic molecule with a lack of a constant dipole moment, is less active in the infrared region. N₂ was chosen as the injection gas mainly as a control group Using the same calculation model, the effects of CO₂/N₂/H₂O on the composition, temperature, and velocity of the flow field are analyzed, and the spectral radiation characteristics of the plume are calculated accordingly.

The external environment and flight speed of an aircraft will change significantly under different operating conditions. In order to analyze in depth the flow and infrared radiation characteristics of the plume under different operating conditions, the flow and infrared radiation changes of the plume were studied at different altitudes and different incoming Mach numbers. Based on this, CO₂ gas was injected to investigate its effect on the flow and infrared suppression of the plume.

Finally, the experiment of injecting gas to reduce the infrared radiation of flames was conducted on the ground. A acetylene-oxygen flame with similar combustion components to the plumes was selected as the detection target. A mid-wave infrared detection system was used to test the effect of injecting CO₂/N₂ on the infrared radiation of the acetylene-oxygen flame.