Abstract:
The bypass dual throat nozzle (BDTN) is a new type of dual-throat fluidic thrust-vectoring nozzle, which introduces secondary flows by a bypass set between the upstream minimum area and the upstream convergent section. The BDTN can achieve a good thrust vectoring performance without setting complex secondary-flow channels in the engine. Numerical studies were performed to analyze the thrust-vectoring performances of a BDTN with injections at the divergent section under different injection locations and secondary pressure ratios. The main results show that the BDTN with injection at the divergent section can improve the thrust-vectoring performances. With the injection location moving backward, the thrust vector angle increases first and then decreases, while the thrust ratio increases slowly. The secondary pressure ratio rise makes the thrust vector angle and efficiency increase to constant values. But it can lead to a thrust loss when it is larger than a certain value. For the optimal case of the modified BDTN, the thrust vector angle and thrust ratio respectively reach 27.59 degree and 0.956, yielding a vector efficiency of 3°/1% per rate of secondary flow, which indicates that the modified nozzle can achieve a fine thrust vectoring performance.