局部干法横焊排水罩内流场数值模拟
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摘要
针对局部干法横向焊接条件,建立排水罩数值模型,对罩内流场进行分析,并进行实验验证。模拟结果表明:随着进气压力的增大,排水效果逐渐变好,但是压力增大到一定程度后,进气压力再增大,排水效果也不会进一步变好。进气气压力小于0.05 MPa时,无法把水完全排干,同时过程中会有外界水的回流现象,气体压力大于0.05 MPa时,可以基本消除这一现象。排水气在罩内产生了一个自下而上的层流流场,气体的流速随压力的增大而增大,越接近母材,该流场速度越大,可以对横焊熔池起到支托作用。最后实验表明:采用较小的气压就能实现排水的目的,排水后罩内环境相对干燥,排水罩内气体流动方式与模拟结果吻合。这为下一步开展局部干法横焊实验提供良好的基础。
Aiming at local dry horizontal welding, a numerical model of drain cover was established. The flow field inside the cover was analyzed and experimentally verified. The simulation results show that with the inlet pressure increases,the drainage effect gradually becomes better, while the pressure increases to a certain extent, with the inlet pressure increasing,the drainage effect will not get better. When the inlet pressure is less than 0.05 MPa, the water cannot be completely drained,and there will be a backflow phenomenon of water outside in the process. When the gas pressure is more than 0.05 MPa, this phenomenon can be eliminated. The drainage gas creates a bottom-up laminar flow field in the cover. The flow rate of the gas increases with the increase of pressure. The closer to the base metal is, the higher the flow rate is, which can play a support role for the molten pool of horizontal welding. Finally, the experiment shows that smaller air pressure can achieve the purpose of drainage, and the environment inside the cover is relatively dry after draining. The air flow pattern in the cover is consistent with the simulation results. Above results lay a good foundation for local dry horizontal welding experiments in next step.
Aiming at local dry horizontal welding, a numerical model of drain cover was established. The flow field inside the cover was analyzed and experimentally verified. The simulation results show that with the inlet pressure increases,the drainage effect gradually becomes better, while the pressure increases to a certain extent, with the inlet pressure increasing,the drainage effect will not get better. When the inlet pressure is less than 0.05 MPa, the water cannot be completely drained,and there will be a backflow phenomenon of water outside in the process. When the gas pressure is more than 0.05 MPa, this phenomenon can be eliminated. The drainage gas creates a bottom-up laminar flow field in the cover. The flow rate of the gas increases with the increase of pressure. The closer to the base metal is, the higher the flow rate is, which can play a support role for the molten pool of horizontal welding. Finally, the experiment shows that smaller air pressure can achieve the purpose of drainage, and the environment inside the cover is relatively dry after draining. The air flow pattern in the cover is consistent with the simulation results. Above results lay a good foundation for local dry horizontal welding experiments in next step.
引文
[1]Li H,Sun Q J,Liu X M,et al.Research status and development trend of horizontal welding technology[J].Advanced Materials Research,2013,753-755:407-412.
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[3]黄军芬,黄继强,孙亚玲,等.水下局部干法焊接中排水罩内的流体状态分析[J].上海交通大学学报,2016,50(10):1622-1626.
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[2]李兰,薛龙,黄军芬,等.水下局部干法焊接圆形排水罩的流体仿真分析[J].焊接学报,2016,37(2):43-46.
[3]黄军芬,黄继强,孙亚玲,等.水下局部干法焊接中排水罩内的流体状态分析[J].上海交通大学学报,2016,50(10):1622-1626.
[4]唐家鹏.ANSYSFLUENT16.0超级学习手册[M].北京:人民邮电出版社,2016.