收扩喷管设计对双S形二元排气系统气动与红外特征的影响

为了研究双S形二元收扩排气系统的气动与红外辐射特性，基于一个基准加力型轴对称排气系统，设计了三种带正尾向全遮挡收扩喷管的双S形二元排气系统模型，通过数值模拟研究了喉道与出口的中心线偏径比差，(S₈?S₉)/D=0.26~0.3，和喉道至出口的宽度扩张比，(W₉?W₈)/D=0.1~0.36，对排气系统气动与红外特征的影响。结果表明:所设计的三种双S形二元收扩排气系统，相比基准轴对称排气系统，在尾向0°~15°角域内红外辐射强度平均降幅在73.4%以上，在上方、下方和侧方90°探测角降幅在60.3%以上，红外辐射强度降幅随(S₈?S₉)/D的减小而上升，随(W₉?W₈)/D的增大而上升，且对(S₈?S₉)/D的敏感较高。三种排气系统的推力系数随(S₈?S₉)/D与(W₉?W₈)/D的降低而上升。

Influence of design of convergent-divergent nozzle on aerodynamic and infrared characteristics of serpentine 2-D exhaust system

In order to investigate the aerodynamic and infrared characteristics of serpentine 2-D convergent-divergent exhaust system, three serpentine 2-D exhaust system with right behind full-shield convergent-divergent nozzle were designed. The effect of centre line offset-diameter ratios between throat and outlet, (S₈?S₉)/D=0.26-0.3, and width expansion ratios between throat and outlet, (W₉?W₈)/D=0.1-0.36, on aerodynamic and infrared characteristics was studied numerically. The results show that relative to the axisymmetric exhaust system, the infrared radiation intensity of three serpentine 2-D convergent-divergent exhaust systems decrease by 73.4% on average in the range of 0°-15° for tail direction, and decrease at least 60.3% in the 90° direction of side, upper, lower detection plane, the decrease of infrared radiation characteristics increases with the decrease of (S₈?S₉)/D, increases with the increase of (W₉?W₈)/D, and more sensitive to (S₈?S₉)/D. The thrust coefficient of three serpentine 2-D convergent-divergent exhaust systems increases with the decrease of (S₈?S₉)/D and (W₉?W₈)/D.