关键词: 射流推力矢量, 逆流矢量喷管, 数值模拟, 非定常流动, 主流附体

Abstract: Unsteady phenomena induced in a counterflow vectoring thrust nozzle by the flow itself are studied by numerical simulation. The results show that when suction back pressure drops to a certain range (about 50.66-60.80 kPa), the main flow oscillates periodically at a location near the collar, and flow parameters (suction flow mass, vectoring angle and synthesis thrust coefficient) also oscillate periodically at a small amplitude, but the coflow keeps stable. This indicates that it is the counterflow shear layer that leads to the unsteady phenomena induced by the flow itself. Mechanism analysis reveals that vortex forms and develops periodically in the counterflow shear layer, and the main flow does not behave unstably. Meanwhile the velocity ratio in the shear layer is much higher than that under steady flow. Therefore the flow exhibits characteristics self-excited oscillation.

Key words: fluidic vectoring thrust, counterflow vectoring nozzle, numerical simulation, unsteady flow, main flow attachment