不同延伸段压力分布的双钟形喷管设计

Design of dual-bell nozzles with different extension pressure distributions

针对不同延伸段压力分布的双钟形喷管,采用特征线法,分别对最大推力、等压分布及等逆压梯度分布的延伸段型面开展了设计,通过仿真手段对设计方法进行了校验,并对不同延伸段压力分布的双钟形喷管工作过程开展了研究。结果表明:最大推力及已知壁面压力的反设计方法能够实现特定压力分布的延伸段型面设计。延伸段逆压梯度分布的双钟形喷管能够在小于发动机起动时间内完成工作模态转换,而延伸段顺压梯度和等压分布构型的模态转换时间较长。相较于最大推力型面,延伸段逆压梯度分布的双钟形喷管存在一定性能损失。当延伸段压升幅值为0.001 5倍的燃烧室压力时,双钟形喷管平均比冲下降了0.44%。

For dual-bell nozzles with different extension pressure distribution, the method of characteristics was used to design the maximum thrust, constant pressure distribution, and positive gradient pressure distribution’s extended contours. Then design methods were verified by simulation,and the operating processes of dual-bell nozzles with different extension pressure distributions were investigated. Results showed that,extended contours with specific pressure distributions could be designed by the maximum thrust and reverse design method with wall pressure known. Modes transition time of dual-bell nozzles with extensions positive gradient pressure distribution was less than engine start-up,but time of models with extensions negative gradient pressure and constant pressure distribution was longer. Compared with the maximum thrust contour,dual-bell nozzles with extension positive gradient pressure distribution had some performance loss. When extension pressure rising value was 0. 001 5 time combustion chamber pressure, the average specific impulse dropped by 0. 44%.