Search

Thrust vectoring can provide fighter with advantages regarding performance, survivability and detectability. Two types of fluidic control Convergent-Divergent nozzle thrust vector technology, which are Shock Vectoring controlling and Throat Shift, are numerically simulated and their performances are analyzed. A nozzle with fixed geometry from nozzle inlet to throat, and fixed length of divergent flap is researched. The relative position of the secondary injecting flow is fixed, and the injecting direction is always vertical to the nozzle main flow. The nozzle flow fields are obtained via CFD numerical simulation. It can be seen from the results that, Throat Shift method is suitable for the nozzle expansion ratio less than 1.5, and Shock Vectoring controlling method is contrary to Throat Shift method, which is suitable for the nozzle expansion ratio greater than 1.5. The Throat Shift method can restrict the nozzle mass flow besides thrust vectoring. The main influence of the secondary mass flow is the ratio of secondary total pressure to main flow total pressure. [ABSTRACT FROM AUTHOR]

The experimental investigation of blockerless cascade thrust reverser based on secondary injection was conducted on the dual flow transonic and supersonic cascade test facility. Effect of parameters including fan outlet pressure ratios, secondary pressure ratios, secondary injection positions and secondray injection angles on the performance of blockerless cascade thrust resver were studied. The final results show that fan outlet pressure ratios and secondary pressure ratios has some complex relationship. When secondary pressure ratio less than a certain value, cascase reverse mass flow decreases with the increase of fan outlet pressure ratio, however if secondary pressure ratio esceed the value, it would present a opposite trend. In the whole experimental conditions, there exist a best secondary injection position (58.77 mm ≤ Xj ≤ 77.87mmgle (θ - 60°) achieving highest thrust reverse. [ABSTRACT FROM AUTHOR]

Jet attachment is a critical restriction for the usage of counter-flow thrust vectoring nozzle, which will lead to the control invalidation of vector thrust. Therefore more attention should be paid to jet attachment phenomenon and detachment control. Based on CFD technology, the jet attachment mechanism, characteristic and forming course were investigated, and two methods for jet detachment were proposed. One is to increase suction pressure, and the other is to enhance nozzle pressure ratio(NPR). The results show that jet detachment would be successfully achieved by implement of suction pressure and NPR control. However, hysteresis phenomenon existed in the suction pressure control course. The jet attachment suction pressure was 60.68kPa, while detachment pressure 65.86kPa. [ABSTRACT FROM AUTHOR]