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保持光传输通道内单一均匀的低吸收系数气体,对削弱内通道中的气体热效应有重要意义。采用气帘作为封装设备,对气帘的结构进行了设计。取气帘入口气体为氮气,出口气体为空气,借助现有计算流体力学软件FLUENT提供的组分输运模型,对气帘进行了数值模拟。结果表明,气帘入口段形成的平面射流可以阻挡外界空气的回流;在氮气与氧气相混合的区域内,尽管气体密度存在一定起伏,但气体密度变化的梯度方向与光传输方向基本是平行的,这种密度起伏只会对光场相位的活塞项产生影响,不会影响激光的远距离传输。最后,对气帘的性能进行了实验测试,实验结果表明,设计的气帘能够对管道内的气体进行密封,并避免了较大光程差的引入。
Maintaining a single uniform, low absorption coefficient gas in the optical transmission channel is of great importance to weakening the gas thermal effect in the inner channel. Air curtain as a packaging equipment, the structure of the air curtain were designed. Taking the air inlet of the air curtain as nitrogen and the outlet air as the air, the air curtain was numerically simulated by using the component transport model provided by the existing computational fluid dynamics software FLUENT. The results show that the plane jet formed at the entrance of the air curtain can block the backflow of the outside air. In the region where nitrogen and oxygen are mixed, the gradient direction of the gas density is basically parallel with the light transmission direction despite the fluctuating gas density, This density fluctuation will only affect the phase of the light field piston, will not affect the long-distance laser transmission. Finally, the performance of the air curtain was experimentally tested. The experimental results show that the designed air curtain can seal the gas in the pipeline and avoid the introduction of large optical path difference.