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基于沸腾两相流动与传热的基本理论,考虑冷却介质的相变,建立了工件淬火过程流固耦合的数学模型。通过对多物理场耦合分析软件COMSOL Multiphysics进行二次开发,完成了模型的数值求解并进行了可靠性验证。结果表明,创建的工件淬火过程流固耦合的数学模型是可靠的,可以较为准确地模拟出淬火工件表面温度随时间的变化历程以及淬火不同阶段的热传递速率特征。工件表面不同位置进入各个沸腾阶段的转折时间不同,棱角处最先进入过渡沸腾、核态沸腾和自然对流阶段,相应地该位置点温度下降也最快。在膜态沸腾阶段,工件表面被一层汽膜包裹,汽膜厚度随着工件高度坐标的增加而增厚。进入到过渡沸腾和核态沸腾阶段后,蒸汽的生成量增大,生成的蒸汽充斥在工件周围并不断上浮至自由液面溢出。
Based on the basic theory of boiling and two-phase flow and heat transfer, a mathematical model of the fluid-solid coupling in the workpiece quenching process was established considering the phase transition of the cooling medium. Through the secondary development of COMSOL Multiphysics, a multi-physics coupling analysis software, the numerical solution of the model was completed and the reliability was verified. The results show that the mathematical model of fluid-structure coupling is established, which can simulate the surface temperature change with time and the heat transfer rate in different stages of quenching. The transition time of different positions on the workpiece surface into different boiling stages is different. The edges of the workpiece first enter the transitional boiling, nucleate boiling and natural convection stage, and the temperature drop at this position is also the fastest. In the phase of film boiling, the surface of the workpiece is covered by a vapor film, and the thickness of the vapor film is thickened as the height coordinate of the workpiece increases. Into the transition boiling and nucleate boiling stage, the steam generation increased, the generated steam flooded around the workpiece and continue to float to the free surface overflow.