薄壁低温容器加注过程降温及热应力特性研究

Study on cool-down and thermal stress characteristics of thin-walled cryogenic containers during filling process

通过FLUENT软件计算一定加注流量下液氮容器加注过程内部流场与温度场变化情况;采用单向流固耦合方法基于ANSYS软件平台构建热-结构模型进行壁面热应力分析。研究表明:数值计算结果与实验数据吻合良好,模型能够有效预测低温加注过程中容器壁面的降温特性和热应力变化与分布规律;底部加注时液体累积过程相对稳定,随液位增长对应不同高度处壁面温度相继降低至接近液体温度后趋于稳定;目标容器最大热变形出现在排气口与上封头区域,最大变形量达3 mm左右;容器壁面外侧一般经历先拉伸后压缩的热应力变化过程,热应力集中区域与加注液面位置保持一致,最高达到近30 MPa,出现在底部封头区域。

The flow field and temperature distribution during filling process of a liquid nitrogen container at a certain filling flowrate were calculated through software FLUENT.Using the software ANYSY,a thermal-structural model was established based on the one-way fluid-solid coupling method,to investigate the thermal stress characteristics of the tank wall.Results show:since the numerical simulations present good agreement with the experimental data,the cool-down and the thermal stress characteristics of the tank wall during cryogenic filling could be reasonable predicted by the current model.The liquid accumulation process is relatively stable when filling from a bottom inlet.As the liquid level increases,the temperature of the tank wall near the interface decreases quickly and then tends to be stable around the liquid temperature.The most serious thermal deformation of the target container exists in the region near the vent outlet and the upper enclosure,with a value of about 3 mm.The outer wall of the container during cryogenic filling usually experiences a tensile thermal stress first and then a compressive thermal stress.The region where the thermal stress is concentrated is in consistent with the position of liquid level.The maximal thermal stress is up to nearly 30 MPa,existing in the bottom region.