管道流的激光湍流相屏模型

Modelling Laser Phase Screen Induced by Turbulence in Channel Flow

基于直接液冷的固体激光技术发展需要,理论研究了管道流冷却流场的湍流特征诱导出激光波前相位畸变的物理机理。利用管道湍流的统计特性,提出了一套管道湍流激光相屏的构造方法。在不可压缩流假设下研究了两种湍流热效应(输运传热和耗散产热)引起的温度脉动对光束波前的影响。结果表明,此状态下光束质量的退化主要来自于输运传热,而非耗散产热。进一步讨论了轻微密度扰动导致的波前畸变量大小。

Inspired by the technique development of solid-state lasers cooled by liquid directly, the phase aberrations at laser wavefront induced by the turbulence in channel flow is investigated theoretically. By means of the statistic characteristic of the channel-flow turbulence, a method to model the laser phase-screen induced by turbulence in channel flow is proposed. Within the assumption of incompressible fluid, there are two kinds of turbulence thermal mechanics, which are heat transfer of transport and heat generation of dissipation, that generate temperature fluctuations in both temporal and spatial regions, and further generate the phase screen induced by the channel-flow turbulence. The numerical result shows that the degeneration of beam quality is mainly caused by heat transfer of transport instead of heat generation of dissipation. The phase aberration induced by the density fluctuations is discussed as well.