A Study For Inner-Outer Flow Coupling Of The Fluidic Thrust Vector Nozzle

Fluidic thrust vectoring nozzle is an important type of thrust vector technology in recent years,which can achieve the deflection of the jet through the flow control without the movement of the nozzle wall.The research designed a passive controlled multi-hole type fluidic thrust vectoring nozzle based on Coanda effect,finds its control law and flow structure,and its interference with the wing.Firstly,the control law of the thrust vector angle is studied.The experimental results shows a serious jump and hysteresis effect on the straight trailing edge nozzle,while the 45 degree oblique nozzle has good continuous control characteristics.The nozzle has been installed on a model aircraft and flown successfully,which confirmed its pitch controllability.Next,the near-wall and the whole flow field of the nozzle are studied through the flow display experiment in the water tunnel,in order to understand the mechanism of the none-linear control law.Flow display shows that when the jet turns close to the wall,there’s a strong shear on the leading edge,the shear-vortex attach to the wall to form a separation bubble,and push out the suction outer flow;when the jet turns away to the wall,outer flow is sucked through the control hole and enlarge the separation bubble until its broken,and the outer flow is sucked from the trailing edge.Finally,the research designs a wing model with trailing edge distributed thrust vector nozzle for the research on jet induced wing-surface pressure change,and its influence on lift,drag and pitch moment coefficient.The lift and moment coefficient curve of the wing is shifted by the deflected jet,lift-to-drag ratio during small AOA can be improved by down thrust vector,and the rolling moment can be controlled under all the AOA of experiment condition along with the reverse yaw moment.