论文部分内容阅读
连续波(CW)DF/HF化学激光器喷管中一般有近20%的氟原子复合为氟分子,这是影响激光器抽运效率和激射强度的重要因素。尤其是壁面复合反应对氟原子的损耗占主要地位。通过喷管型面设计等方法减少氟原子的复合效果不共明显。结合航空领域中气膜冷却方案设想通过在喷管收缩段位置处注入氦气层,隔离氟原子气流与喷管壁面,实现降低氟原子损耗的目的,同时保护喷管壁面及喉道部分避免过度烧蚀。数值模拟结果显示此方法可同时实现对喷管壁面的冷却保护和有效提高氟原子的冻结效率。但注入的氦气将占据部分气流通道,影响主气流在喷管中的传输。在主气流属性保持不变的情况下,喷管出口平面(NEP)上氟原子绝对流率将下降。针对引入的不足,提出了几种改进方案。
Nearly 20% of the fluorine atoms in a continuous wave (CW) DF / HF chemical lasers nozzle are complexed to fluorine molecules, which is an important factor that affects the pumping efficiency and lasing intensity of the laser. In particular, the composite wall reaction of fluorine atoms occupy the main loss. Through the nozzle surface design and other methods to reduce the compound effect of fluorine atoms are not obvious. Combining with the film cooling scheme in the aviation field, it is envisaged to reduce the fluorine atom loss by injecting a helium gas layer at the position of the contraction section of the nozzle to isolate the fluorine atom gas flow from the nozzle wall, and to protect the nozzle wall and the throat part from excessive Ablation. Numerical simulation results show that this method can achieve the cooling protection of nozzle wall and effectively improve the freezing efficiency of fluorine atoms. However, the injected helium will occupy part of the gas flow channel, affecting the main gas flow in the nozzle. With the main stream properties unchanged, the absolute fluorine atom flow rate at the nozzle exit plane (NEP) will decrease. In view of the problems introduced, several improvement schemes are put forward.