一种矢量增强型双喉道射流推力矢量喷管的数值模拟

Numerical investigation of a vector-enhanced dual-throat thrust-vectoring nozzle

为克服双喉道射流矢量喷管矢量角偏小的缺点,提出了一种矢量增强型双喉道矢量喷管的设计概念:在喷管尾部增加一扩张段,利用流体的附壁效应使主流在扩张段中进一步偏转,从而获取更大的矢量角.首先对设计概念的可行性进行了仿真分析,而后对扩张段的设计规律进行了研究.结果表明,在喷管尾部附加扩张段可显著强化其推力矢量性能,使矢量角达到20°以上,但也导致了一定的推力损失.在研究范围内,扩张段扩张角、扩张段长度、扩张段型线等设计参数对喷管的矢量效率、推力系数以及内部流态均有着显著影响,而在扩张段开缝则可以作为一种抑制尾喷流过膨胀的有效措施.若将内凹型扩张段与开缝方案相结合,仅需消耗2.8%的次流便可获得24.12°的推力矢量角和0.929的推力系数.

A design concept of vector-enhanced thrust-vectoring nozzle was proposed to overcome the shortcoming of dual-throat thrust-vectoring nozzle of small vector angle.In the newly designed nozzle,two expansion ramps were added after the second throat of the nozzle to achieve greater vector angle using the Coanda effect.The feasibility of the design concept was firstly analyzed by 2-D simulation,and then the design law of the expansion ramps was studied.Results show that,with the expansion ramps,the efficiency of thrust-vectoring is remarkably enhanced with a vector angle over 20°.But some loss of thrust efficiency is also found.In the researched parametric range,the expansion angle,expansion length and expansion contour affect obviously the performance and the internal flow pattern of the nozzle.Furthermore,placing slots on the concave expansion ramps can suppress the overexpansion of the exhaust flow effectively,and obtain a vector angle of 24.12° and a thrust ratio of 0.929 with consumption of only 2.8% secondary flow.