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

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.