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针对大口径宽波段激光发射通道密封防护较难的问题,提出了正压净化通风密封方法。该方法利用送入内通道的干燥洁净的净化气流,排出原有空气并充满内通道,基于正压原理阻挡外界空气和微粒,实现发射通道的密封。借助计算流体力学软件Fluent对激光发射内通道的正压通风流场进行了连续相和离散相的数值模拟,发现正压通风方法形成的正压净化气流不仅可以阻挡外界空气,而且在小于4.71E-3 kg/m3的颗粒浓度范围内,净化气流对空气中各种粒径的尘埃颗粒也起到很大阻挡作用。另外,通过分析流场的气体折射率的非均匀分布发现,对于0.8~10.6μm波段范围的激光,正压通风引起的光程差约为0.32μm。正压通风实验的测量结果显示,颗粒浓度与仿真曲线变化趋势基本一致,证明了正压通风方法的有效性。
Aiming at the problem that the large-diameter wide-band laser emission channel is difficult to seal and protect, a positive pressure purifying ventilation sealing method is proposed. The method utilizes a clean and clean purge gas flow sent into the inner channel to expel the original air and fill the inner channel, and block the outside air and particles based on the principle of positive pressure so as to realize the sealing of the transmitting channel. The numerical simulation of continuous flow and discrete flow in the positive pressure ventilation flow field of laser emission inner channel was carried out by computational fluid dynamics software Fluent. It was found that the positive pressure purge flow formed by positive pressure ventilation not only can block the outside air, but also in less than 4.71E -3 kg / m3 of particle concentration range, the purified air flow on the air of various particle size dust particles also played a large barrier. In addition, by analyzing the non-uniform distribution of the gas refractive index of the flow field, it is found that the optical path difference caused by the positive pressure ventilation is about 0.32 μm for the laser in the wavelength range of 0.8~10.6 μm. The results of positive pressure ventilation experiments show that the trend of particle concentration and simulation curve are basically the same, which proves the effectiveness of positive pressure ventilation method.