飞翼无人机保形非对称尾喷管设计与流场特性

Conformal Asymmetry Nozzle Design and Flow Field Characteristics of Flying Wing Unmanned Aerial Vehicle

基于飞翼布局无人机隐身与保形设计要求，设计了不同面积比的四边形和圆矩形2类非对称尾喷管，并利用数值模拟方法对无人机内外流耦合流动进行了计算分析，获得了无人机全机纵向气动性能与尾喷管三维流场特性。结果表明：保形非对称尾喷管可用于改善飞翼无人机的纵向力矩特性，且圆矩形喷管升阻特性和力矩特性比四边形喷管更优；收敛型喷管（面积比Ar≤1.0）无法在设计点（发动机喷口）而是在尾喷管出口处形成喉道，并在喉道处形成强激波阻滞喷流排出；随着面积比增大，轴向推力系数先增大后减小，存在最佳面积比，而且相同面积比下圆矩形喷管比四边形喷管推力性能更佳；扩张型喷管内激波的强度随着面积比增大变得更强，圆矩形喷管结尾处的激波角比四边形喷管小，喷流阻滞作用更小；对于此类飞翼布局无人机采用面积比为1？2～1？4的圆矩形喷管，将获得较理想的气动性能。

Asymmetry nozzle of flying wing UAV （ Unmanned Aerial Vehicle ） was designed based on stealth and conformal requirements;this was set up into quadrilateral nozzle and circular-rectangle nozzle with different area ra-tios. The coupled numerical simulation was also carried out on the inflow/outflow integrated for flying wing UAV, and it is applied to studying the longitudinal aerodynamic performance of UAV and three-dimensional flow field characteristics of nozzle. Results and their analysis indicate： asymmetry nozzle of flying wing UAV can be used to improve the moment characteristic, and the lift/drag characteristic of circular-rectangle nozzle show better than quadrilateral nozzle;the convergent nozzle whose area ratio Ar≤1.0 will form the throat at the nozzle vent but not the design point expected at the engine vent, and that the strong shock will form at the throat which is not condu-cive for jet-flow to exhaust;with the increase of the area ratio, the axial thrust coefficient firstly increases and then decreases so that we could believe that there is an optimal area ratio, and that the circular-rectangle nozzle obtains better thrust performance than the quadrilateral nozzle along with the same area ratio;the intensity of shock wave al-so becomes stronger in the nozzle with increasing area ratio, and the shock wave angle formed at the root of circular-rectangle nozzle is smaller than quadrilateral nozzle which causes less blocking for jet-flow. Generally speaking, it is better to adopt circular-rectangle nozzle for the flying wing UAV with area ratio between 1？2 and 1？4;this leads to ideal aerodynamic performance.