平行四边形截面的旁路式双喉道气动矢量喷管数值研究

将异型出口设计与气动推力矢量喷管结合,提出了平行四边形截面的旁路式双喉道气动矢量喷管(bypass dual throat nozzle,BDTN),并与基准矩形截面的BDTN进行流场结构及气动性能的对比研究。三维数值计算表明:平行四边形构型与矩形构型具有相同的气动性能变化规律;相较于基准矩形BDTN构型,由于壁面倾斜导致流场结构变化,平行四边形构型在矢量状态下的俯仰矢量角及推力系数有所降低,但对非矢量状态下的推力系数和流量系数影响不大;壁面倾角是性能变化的重要因素,相同落压比时壁面倾角越小,矢量角越小,壁面倾角不小于60°时喷管的稳定矢量角均可达10°以上，最大矢量角均可达15°以上;平行四边形出口增强了尾喷流与环境气流的掺混,出口射流中心线速度衰减大大加快,有利于提高红外隐身特性。

Numerical study of bypass dual throat nozzlewith parallelogram cross-section

A parallelogram section bypass dual throat nozzle(BDTN) was proposed by combining the heterotypic outlet design with the fluidic thrust-vectoring nozzle, and then a comparative study of the flow filed structure and aerodynamic performance with the basic rectangle BDTN was carried out. The results of three-dimensional numerical simulation showed that the parallelogram configuration had the same aerodynamic parameter variation law as the rectangular configuration. Compared with the basic rectangle BDTN, the flow field of the parallelogram configuration changed due to the inclination of sidewalls, resulting in the decrease of the pitch vector angle and thrust coefficient in vectoring mode, while it had little effect on the thrust coefficient and flow coefficient in non-vector mode. The sidewall inclination angle was an important factor for the change of nozzle performance. Under the same nozzle pressure ratio, the lager inclination angle indicated the smaller vector angle. When inclination angles were not less than 60°, stable vector angles above 10° and maximum vector angles above 15° could be obtained. The parallelogram outlet had a better blending effect on the exhaust jet, which could greatly accelerate the attenuation of the centerline velocity of jet flow and contribute to improve the infrared stealth characteristics.