氧碘化学激光器（COIL）在化学反应条件下,由于光腔及扩压器的气流通道内存在残余化学反应放热,从而导致“热堵”现象发生,影响了扩压器的正常启动及光腔内超声速流场的流动品质。采用数值模拟方法对COIL光腔与超声速扩压器流道内的化学反应流场进行研究,对超声速扩压器插入段的长度、楔形体的数量级扩散段长度对化学反应流场的影响进行研究。数值模拟结果表明：通过优化插入段及楔形体长度、取消扩压器侧壁的半楔形体,改善了因化学反应放热对光腔及扩压器流场造成的不利影响。优化后,光腔内的流动不再受气流分离产生的斜激波的影响,扩压器二喉道内的分离现象消失,扩压器壁面的分离区减小,出口流动更加均匀,“热堵塞”现象消失。化学反应条件下的气流总压损失比冷流时提高约15%,光腔与扩压器的总压恢复系数为0.426,进出口的静压比为3.75,比优化前提高了约25%。

Within a typical chemical oxygen-iodine laser(COIL), the residual heat could cause “heat blocking” in the pressure recovery system due to the chemical reaction in the laser cavity and the diffuser, which contributes to the failures of the diffuser start-up and the uniformity deteriorations of the supersonic flow in the cavity. For the pressure recovery performance, the total pressure losses due to the reaction could be up to 15%. By numerical simulations of the reaction flow in COIL cavities and supersonic diffusers, we investigated different configurations of the COIL supersonic diffuser, focusing on insert section length, number and shape of wedges, and diffuser length. The results show that under the adverse effect of residual reaction, the performance of the pressure recovery system can be improved by optimizing the insert section, adjusting the wedge length, and removing the semi-wedges in the diffuser side wall. The optimal diffuser geometry proposed in this paper proves to be “heat-blocking-free”, where the supersonic flow in cavity is not affected by the oblique shock waves due to separation. There is no separation in the choke of the diffuser. The separation area in the diffuser side wall decreases, and a more uniform outflow is achieved. For the pressure recovery system and COIL configuration in the paper, the optimal geometry achieves a total pressure recovery ratio of 0.426 and a static pressure ratio of 3.75, which are 25% better than the original design.