脉冲射流强化混合对喷流红外辐射特性的影响

计算了脉冲射流强化混合喷流在3~5 μm波段的红外辐射特性,并与无脉冲激励喷流的红外辐射特性进行了比较,分析了脉冲射流强化混合对喷流红外隐身的效果.流场及温度场采用有限体积法和重整化群(RNG,Renormalization Group)k-ε湍流模型求解N-S方程得到.喷流的红外辐射强度采用有限体积法结合窄带模型求解吸收发射性介质辐射传输方程得到.计算结果显示,在亚音速条件下,少量的射流流量(占3%的主流流量)就可以使核心区长度缩减一半以上,在天顶角90°方向探测喷流的红外辐射强度,各个方位角上都有较大衰减,与激励源垂直的平面上的衰减效果相比,与之平行的平面上的更为强烈. 

Effect of jet mixing enhancement by pulsed blowing on infrared radiation of plume

A three-dimensional infrared (IR) radiation code of the plume was developed by the finite volume method (FVM) coupled with narrow band model in non-gray absorbing-emitting media. The infrared radiation of the unforced plume and the forced plume, which is mixed by injecting high amplitude and low mass flux plused slot jets into subsonic shear layer were simulated by the code. The 3-D flow field of the jet was simulated numerically by FVM, renormalization group(RNG) k-ε turbulence model. The results indicate that small injection flow rates (about 3%) can make sharp increases in both velocity and temperature decay rates at middle Mach number. At the zenithal angle of 90°, the IR radiation of the plume at each azimuth angle has tremendous reduction, and the decreases in the plane parallel with the actuators are larger than those in the plane perpendicular to the actuators.