为了得到具有优良的射流流场激光喷嘴, 设计了一种组合型超音速喷嘴, 建立了该喷嘴计算流体动力学(CFD)分析所需的控制方程。其中湍流模型采用标准k-ε方程, 计算网格采用三角形非结构网格。基于有限体积法对控制方程进行离散并采用耦合式求解器求解。利用SIMPLEC算法解决速度与压力耦合问题, 进而实现对喷嘴流场分析。分析结果表明超音速喷嘴最佳入口压力就是其设计压力(7×105 Pa), 此时其射流流场特性最好, 适合于高速、大厚度激光切割。将CFD分析结果与已有纹影图实验方法的结果进行对比, 发现二者具有较好的一致性, 证明了CFD方法的可行性。

In order to obtain excellent gas jet from laser’s nozzle, a combinatorial supersonic laser jet cutting nozzle is designed. The control equation for computational fluid dynamics (CFD) is also derived, where standard k-ε model is used for onflow. Using triangle unstructured grid for computing, applying finite volume algorithm to discretizing the control equation, the equation is solved by coupling solver. Velocity and pressure coupling problem is solved by applying SIMPLEC algorithm, and further more the jet field analysis is fulfilled. The analysis indicate that the optimum pressure-inlet is its designed pressure (7×105 Pa), under which the jet field performs best and so it can be sufficiently applied to cut thick workpiece with high velocity. Comparing the results of CFD analysis with that of image lab obtained, it is found that the two results have a quite good consistency. Thus, the CFD analyzing method is proved practical.