Fluid-thermal-solid Coupling Numerical Simulation Of An Engineering Structure

Temperature adjustment is one of the key parts of cryogenic-fluid experiment,which can effectively improve the experimental efficiency,save the experimental cost and achieve the experimental design objective.However,with the temperature adjusting too fast,the coupling effects of temperature gradient and flow field would cause the structure being subjected to stress and deformation,even leading to strength failure and damage of material.On the contrary,adjusting temperature too slow would significantly affect the experimental efficiency.Therefore,in the process of temperature adjustment,it is necessary to use Computational Fluid Dynamics(CFD)or other simulation methods to explore the timedomain characteristics of the model and environment,and thus find an optimal temperatureadjusting scheme.In this paper,basing on ANSYS Workbench,the weak-formed fluidthermal-solid coupling simulations are systematically performed to research the cooling and heating conditions of the model.Then,the optimal temperature-adjusting scheme is determined,and thus lays a preliminary foundation for the cryogenic-fluid experiment.The specific research contents and main conclusions of this paper are listed as follows:(1)The mechanical properties and thermal-physical parameters of the materials(i.e.18Ni(200)and 18Ni(250))are measured at different temperatures,and thus provide experimental data for the subsequent fluid-thermal-solid coupling simulation.(2)Different mesh-generation methods,including structured,unstructured and mixed elements,are used to check the mesh dependence of the model.To simultaneously guarantee computational accuracy and efficiency,an applicable calculating model is selected for subsequent studies.(3)With the SST k-omega turbulence model,transient calculation method is used to analyze the temperature field of the experimental model and temperature-adjusting environment under different design conditions.A specific temperature-adjusting scheme is provided for the model to achieve the temperature-adjusting objectives designed before.(4)Based on the flow field simulation results,the static structure analysis of the model is carried out to obtain the corresponding deformation/stress distributions.Under typical working conditions,the maximum value in the highest-stress area(i.e.the connection between the sides and main body of the structure)is 687 MPa,which is far less than the yield strength of material 18Ni(200)(i.e.1412.23MPa).And the reliability of temperatureadjusting scheme is effectively verified.(5)Using a simplified model,the correlation between geometric parameters(e.g.wall thickness of the main body)and temperature-adjusting time is explored,and some suggestions for improving the temperature-adjusting efficiency are provided.Within the range of experimental requirements,the cooling time and wall thickness or other parameters show close correlations to a certain extent.Finally,two empirical formulas are given,which provide theoretical bases for subsequent experiment design.