喷管、光腔及压力恢复系统一体化设计

Integrative design of nozzle,cavity and pressure recovery system

对氧碘化学激光(COIL)系统的喷管和扩压器进行了3维数值模拟,对比分析了几种喷管和扩压器的设计方案,计算了从光腔入口到扩压器出口的气动力学过程。光腔内主副气流借助翼片辅助方法实现充分混合,翼片长0.77 cm,宽0.254 cm,满足气流混合要求。扩压器是1/4结构,即计算区域为入口截面高30mm、宽60 mm的长方型,之后等截面延续500 mm,然后宽度仍然不变,高度以4°角扩张,延续700 mm,最终的出口截面高度为79 mm。采用空气入射,入口处(光腔出口)马赫数3.2,静压1232 Pa,温度110 K;计算得到出口处总压13300 Pa,总温300 K。结果表明:出口静压超出入口静压近10倍,该扩压器很好地起到了压力恢复的作用,而总压下降到1/4.5左右(从60648 Pa到13300 Pa),从而能够减轻后续的引射器的工作压力。利用高光腔压力设计可以减少一级引射器,达到整个系统小型化设计的目的。

The 3-dimensional numerical simulation of nozzle and diffuser for COIL system is performed. Several nozzle and diffuser designs are compared and analzed. The gasdynamic process from cavity inlet till diffuser outlet is computated. The sufficient mixing of primary and secondary flows in cavity cart be reached by means of aiding tab, which is 0.77 cm× 0. 254 cm. The computational model of diffuser is the 1/4 construction, of which the input cross-section is 30 mm×60 mm. After keeping the same cross-section size till the length is 500 mm, the diffuser is continued with the same width and 4°divergent angle in height till the length is 700 ram. The final output area size of diffuser is 79 mm× 60 mm. The input （output of cavity） gas condition of diffuser is air with Mach number of 3.2, static pressure of 1 232 Pa and temperature of 110 K. The output condition is total pressure of 13 300 Pa and total temperature of 300 K. The results show that the output static pressure is more than 10 times high as the input one and this diffuser has very good pressure recovery capability. On the other hand, the total pressure decreases till 1/4.5 （from 60 648 Pa till 13 300 Pa）, which can lessen the ejector＇s working load then. Using the high static pressure cavity design can at least remove one stage of ejector in order to miniaturize the whole system.