球面收敛二元矢量喷管气动及红外特性研究:模拟地面状态

采用数值模拟方法对涡扇发动机排气系统球面收敛二元矢量喷管的气动和红外辐射特性进行了研究，研究仅针对地面状态和俯仰偏转.结果表明:俯仰偏转角在小于20°范围内，俯仰偏转对排气系统推力系数和总压恢复系数的影响微弱，气动推力矢量角与俯仰偏转角几乎相等；由于气体的容积性热辐射特征，喷管俯仰偏转角的变化引起高温喷流红外辐射的方向性变化明显，喷管俯仰偏转时的热喷流在3~5μm波段红外辐射呈现一定幅度的增加；排气系统在3~5μm波段的红外辐射峰值随俯仰偏转角的增加而趋于减小，其出现位置小于俯仰偏转角；在大的俯仰偏转角下，排气系统在垂直探测平面上方的红外辐射较无矢量偏转情形有所降低，但在探测面下方却有明显的增强，导致另一个峰值的出现. 

Investigation on aerodynamic and infrared characteristics of spherical convergent two-dimensional vectoring nozzle: simulating ground status

Numerical investigation was performed to study the aerodynamic and infrared performances of spherical convergent two-dimensional vectoring nozzle adopted in turbofan engine exhaust system,only the ground status simulation and pitch deflection were taken into consideration.Results showed that,the pitch deflection had a very weak impact on the thrust coefficient and total pressure recovery coefficient of exhaust system when the pitch deflection angle was less than 20 degree.The aerodynamic thrust vectoring angle was nearly the same as the pitch deflection angle.Due to the feature of volumetric thermal radiation of gas,the variation of nozzle pitch deflection angle resulted in significant change of infrared radiation directionality of hot plume.The infrared radiation of hot plume in 3-5μm band was also increased within a certain scope in relation to the no-vectoring case.With respect to the total infrared radiation of exhaust system in 3-5 μm band,the peak infrared radiation intensity decreased as the pitch deflection angle increased.The detecting angle corresponding to the peak infrared radiation intensity was smaller than the pitch deflection angle.Under a big pitch deflection angle,the total infrared radiation of exhaust system viewed from top in the vertical plane was lower than that of no-vectoring case.However,the total infrared radiation of exhaust system viewed from bottom in the vertical plane was higher than that of no-vectoring case,resulting in a secondary peak value.