一种仿生蜻蜓式垂直起降喷管的流动特性分析及优化设计

Flow characteristic analysis and optimization design of a bionic dragonfly vertical takeoff and landing nozzle

为提高飞行器排气系统的隐身性及机动性,提出了一种仿生蜻蜓式垂直起降喷管,并对不同模式下喷管的流动特性及流道优化进行研究。首先运用CFD方法分别对常规巡航、S形隐身以及垂直起降模式下的蜻蜓式垂直起降喷管进行流场数值仿真,探究该喷管的流动特性;然后在此基础上,分别研究喷管各舱段间相对转角对S形隐身模式及垂直起降模式下喷管气动特性的影响规律,得出相应模式下气动性能较优的蜻蜓式垂直起降喷管。研究结果表明:相同条件下,常规巡航模式下喷管气动性能较优;各舱段相对转角对喷管气动性能有较大影响,其中转角θ_(1)、θ_(2)、θ_(3)分别为-34°、12°、22°的S形隐身模式喷管以及θ_(1)、θ_(2)、θ_(3)分别为35°、30°、30°的垂直起降模式喷管的综合气动性能较优。

In order to improve the stealth performance and maneuverability of the aircraft exhaust system,this paper proposes a bionic dragonfly vertical takeoff and landing nozzle,whose flow characteristics and optimization under different modes are investigated.The Computational Fluid Dynamics approach is used to simulate the flow fields of this nozzle in the cruise,S-type stealth,and vertical takeoff and landing modes.Based on the analyses of the obtained flow fields in each mode,the effects of the relative angle between adjacent nozzle sections on the nozzles's aerodynamic characteristics in the S-type stealth mode and the vertical takeoff and landing mode were studied,yielding an optimized combination of the relative angles for each mode.The results show that,under the same condition,the conventional cruise-mode nozzle has a better aerodynamic performance;the relative angle of adjacent nozzle sections significantly impacts on the aerodynamic performance of the nozzle.The overall aerodynamic performance of the S-type stealth mode nozzle with an angle combinationθ_(1)=-34°,θ_(2)=12°andθ_(3)=22°and the vertical takeoff and landing mode nozzle withθ_(1)=35°,θ_(2)=30°andθ_(3)=30°are better.