对流冷却下板状激光介质热效应的三维模拟

高热负荷固体激光介质的热效应是制约激光器功率提高的严重障碍。以不均匀换热系数模型为基础,研究了具有非均匀内热源的侧面双向抽运板状激光介质在强制对流冷却下的耦合换热问题。结果表明:忽视对流换热系数的非均匀性将导致介质温度场和热应力场计算结果偏低;在平均导热系数取值基准下,介质热物性的温度依存性对其温度分布影响不大。与一维理想模型(均匀换热系数、常物性)的结果不同,采用三维模型并考虑入口段效应时,介质最大应力随R eyno lds数的增大而减小,而对介质膨胀系数的非线性作用不敏感,采用平均膨胀系数即可满足要求。

Three-dimensional simulation of thermal effects in a laser slab cooled by forced convection

Thermal effects in high-power solid-state laser slabs limit enhancements of their laser powers.The coupled heat transfer in a laser slab cooled by forced convection with two pumped sides and a non-uniform interior heat source was analyzed using a non-uniform heat transfer coefficient model.The results show that neglect of the non-uniformity of the convective heat transfer coefficient will lead to underestimation of the temperature and thermal stress fields and that the temperature dependence of the slab thermal properties slightly influences the slab temperature distribution.Unlike the results of a one-dimensional ideal model with uniform heat transfer coefficients and constant physical properties,the three-dimensional model with consideration of the entrance effect indicates that the maximum stress in the slab decreases with increasing Reynolds number.Since the maximum stress in the slab is insensitive to the slab expansion coefficient non-linearity,an average expansion coefficient can be used in the simulation.