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建立了自由射流模型,采用了可压缩流体轴对称N-S方程和RNGkε-模型,重点分析了出流为欠膨胀波时的马赫盘(MSD)结构。对出口静压为6.145×105Pa的自由喷射外流场进行数值仿真,描述了不同出口马赫数时的射流场结构,分析了马赫盘与喷嘴出口马赫数之间的关系,揭示了随着出口马赫数的增加,马赫盘的宽度呈现出收敛趋势,表明超音速喷嘴设计在保证常用工作压力时不出现过膨胀的情况下应适当提高出口马赫数。揭示了实际切割过程中,随着出口马赫数不断增大,马赫盘将收敛于一固定位置。对求解模型进行流场可视化对比验证,证明了仿真结果的准确性和结论分析的有效性。
A free-jet model was established. Axial symmetry N-S equation and RNGkε-model of compressible fluid were adopted, and the Mach disk (MSD) structure was analyzed emphatically. The free jet outlet flow field with exit static pressure of 6.145 × 105Pa was numerically simulated. The jet field structure at different exit Mach number was described. The relationship between the Mach number and the nozzle exit Mach number was analyzed. The increase of the number, the width of the Mach plate showed a convergence trend, indicating that supersonic nozzle design to ensure that the common working pressure without over-expansion should be appropriate to improve the export Mach number. It reveals that Mach-plate will converge to a fixed position as the Mach-number of exit increases in the actual cutting process. The flow field of the solution model is verified by comparison with the flow field, which proves the accuracy of the simulation results and the validity of the conclusion analysis.