Investigation Of Infrared Stealth Technology Of Transverse Jets Suppressing Infrared Radiation Of Plume

Based on the development of aircraft infrared stealth technology, we intended to develop an active method to enhance jet mixing and infrared radiation suppression in this paper. We intended to enhance the high-temperature plume mixing and have a good infect on infrared suppression by injecting transverse jet into the shear layer of the plume in different ways.On the basis of an axisymmetric convergent nozzle in this paper, we use a kind of new active technology to enhance the outflow and heat plume mixing. To realize the optimization of the mixing effect and improve the effect of infrared suppression under the condition of less cooling jet, we changed the way of transverse jet injection. We carried out the research through numerical simulation and experimental research. The main contents included:①he transverse jets were arranged at the nozzle outlet, impacts of jet angle’a’,mass flow rate’m’ and arrangement number’n’on aerodynamics and infrared radiation under the steady condition were studied through numerical simulation.②hanged the arrangement of transverse jet and injected pulsed jets, the mass flow rate of which changed with time, to study the aerodynamic and infrared radiation characteristics at different time and different detecting plane through numerical simulation.③We had conducted a experiment to research the influence on the infrared radiation of plume, which is mixed by injecting transverse jets into the subsonic shear layer.The numerical simulation results indicated that jet mixing enhanced and the infrared radiation of the plume reduced tremendously after injecting secondary transverse jet into the subsonic shear layer of the nozzle outlet. Jet mixing enhanced more effectively and the infrared radiation reduced more obviously as the mass flow rate getting bigger. Jet mixing enhanced better and the infrared radiation decreased when jet angle ’a’ was90°and arrangement number’n’getting bigger.Then the arrangement of transverse jet was changed by two, when the variation law of the two transverse jets over the time were the same, total mass flow rate of two transverse jets were different at different time, mixing characteristics would change over time, infrared radiation of plume also varied. The decreases in the detecting plane perpendicular to the transverse jets were larger than those in the detecting plane parallel with the jet. The infrared radiation of plume decreased by48%at90°etecting point. When the variation law of the two transverse jets over the time were different, total mass flow rate of two transverse jets were constant at different time, mixing characteristics would not change over time, infrared radiation of plume also varied. The decreases in the detecting plane perpendicular to the transverse jets were larger than those in the detecting plane parallel with thejet. The infrared radiation of plume decreased by41.3%at90°detecting point. Then four transversejets surrounded at the nozzle outlet, the mass flow rate of two transverse jets at Y axis direction variedby sinusoidal variation over time and those of two transverse jets at Z axis direction varied by cosinevariation over time, the infrared radiation of plume varied at different detecting plane at differenttime,which decreased up to50%at90°detecting point.In the experiment, we detected the spectral intensity at different detecting plane. The resultsindicated that the radiation intensity at0°detecting point was much stronger than others and decreasedwith the detecting angle increasing. After injecting the transverse jets into the plume,the infraredradiation intensity were reduced.When the mass flow rate of transverse jets was3%of that of plume,the infrared radiation reduced by60%at90°detecting point in the detecting plane perpendicular tothe transverse jets.