以锥型和收敛型两种典型的会聚型喷嘴为对象，建立了包含工件的激光切割平面对称三维撞击射流模型，采用N-S方程积分形式和RNG k-ε湍流模型，对辅助气体流场结构进行计算，研究喷嘴工件距对钢板切缝的气体流场影响。发现收敛型喷嘴的切缝气体动力学性能优于锥型喷嘴，且至少存在两个合理的切割区域。最后，进行了激光切割实验和分析。

Adopting two typical assemble nozzles which called taper nozzles and convergence nozzles as targets, the three-dimensional and plane symmetrical impinging jet model of laser cutting comprised workpieces is established and the flow field of assist gas is computed by adopting the integral form of N-S equation and RNG k-ε onflow model. The flow structure of assist gas and study the influence of standoff distance on flow field in cutting slot are calculated. The investigation reveals that the dynamics in cutting slot of convergence nozzle is more predominant than that in taper nozzle and at least two reasonable cutting scopes exist to make the assisting gas in cutting slot have predominant dynamic characteristic. In the end, laser cutting experiment and analysis are shown.