Numerical simulation of thermal–structural behaviour of liquid helium tank during filling process

In a large-scale helium cryogenic system, a tank is used to store liquid helium. To predict the cooling behaviour and thermal performance of the tank during liquid helium filling, a simple and efficient computational fluid dynamics methodology was used. The phase transition and temperature distribution in the tank were simulated through a two-dimensional thermal–fluid–structure coupling model. Based on the temperature data in the simulation, the stress and deformation on the wall surface were calculated using a finite element model. Liquid helium filling processes with different mass flow rates are analysed and compared, and the impacts on phase transition, liquid temperature, and thermal effects in the tank wall are discussed. The results show that the height of the liquid filling level has a significant influence on the boiling evaporation rate, the degree of temperature stratification, and the flow structure. The gas disturbance at the bottom of the tank is obvious, and the gas–liquid interface is in an unbalanced state, especially with a low liquid level. The simulation data indicate that the mass flow rate has a greater impact on the initial stage of filling. Oscillation of the gas–liquid interface is more evident with a lower mass flow rate. With an increase in the mass flow rate, temperature stratification becomes increasingly severe. According to the thermal calculation data, a filling rate that is too high or too low can lead to higher stress and larger deformation on the tank wall.