Numerical Simulation Of Mixing Cold And Hot Fluid In T-junction And Structure Stress Of T-junction

In the process of actually transporting fluid in a pipeline system,the flow of fluid in the pipeline is mainly unsteady flow.When there is a non-isothermal fluid in the tube,the wall temperature is affected by the fluid.Temperature changing of the pipe wall can cause different degrees of free contraction or expansion of the pipe.However,due to the structural constraints of the pipeline itself and the constraints of external conditions,the pipeline cannot be freely deformed,resulting in thermal stress on the pipe wall.When the thermal stress is an alternating stress,it may cause thermal fatigue failure of the pipe.Therefore,the analysis of the flow and heat transfer characteristics of fluids in pipelines is of great significance for optimizing pipeline design.Based on the previous research,this paper uses the large eddy simulation(LES)turbulence model to simulate the mixing process of T-tube and embedded T-junction,and obtains distribution of temperature and velocity field in the T-tube.Temperature dimension,temperature fluctuation intensity and temperature fluctuation frequency were analyzed using dimensionless temperature,dimensionless RMS temperature and temperature PSD,indicating that the embedded T-junction can improve the mixing efficiency of hot and cold fluids and reduce the supervisor fluctuations in wall temperature and helps to weaken the thermal fatigue of the main pipe.Based on the flow field analysis,the unidirectional fluid-solid coupling numerical simulation of the T-tube and the embedded T-tube was carried out.Through the analysis of stress and deformation displacement,the stress distribution states of two T-tubes are revealed,and the mechanism of the embedded T-junction to improve the stress of the pipeline is revealed.The main research of this paper is as follows:(1)Establish a mathematical model for numerical simulation of mixing of hot and cold fluid in T-junction and embedded T-junction,and a fluid-solid coupling method for structural static simulation of two T-tubes;(2)Under the conditions of wall jet,deflecting jet and impinging jet,the LES turbulence model is used to simulate the mixing process of the hot and cold fluids in the the two structures of T-tubes,revealing the flow and heat transfer mechanism of the hot and cold fluid mixing process in the tube;The flow field temperature and velocity distribution in the T-tubes of the two structures are analyzed,and the influence of the embedded T-junction on the flow field temperature and velocity distribution in the tubes is illustrated;(3)The wall temperature field and pressure field obtained under wall jet conditions are taken as the external load of the solid pipe.The unidirectional fluid-solid coupling numerical simulation of the T-tube and embedded T-junction is carried out,and the stress and deformation displacement are compared and analyzed.Size,revealing the mechanism of the embedded T-junction to prevent thermal fatigue failure of the pipeline;This study preliminarily explored the influence of the embedded T-junction on the temperature fluctuation in mixing process of the hot and cold fluid.It reveals that the structure of the embedded T-junction reduces the temperature fluctuation in mixing process of the hot and cold fluid.The foundation provides a basis for the optimized design of the T-junction structure and the reduction of stress.