Numerical Simulation And Flow Field Analysis Of Gas-liquid Two-phase Flow Around A Staggered Tube Bundle

The phenomenon of gas-liquid two-phase fluid flowing around blunt objects is very common in industrial production,especially in heat exchangers.Many heat exchangers achieve the purpose of exchanging heat through the phase change of the surrounding fluid.The phase change can accelerate the heat.Exchange,but it may cause bubbles to accumulate on the surface of the tube bundle,so that the heat of the heat exchange equipment cannot be exchanged,which will cause the heat exchange equipment to overheat,and the heat exchange equipment will also be fatigued and damaged,reducing the use of industrial equipment Life expectancy will even be directly destroyed during the work process,causing immeasurable losses to the company and the country.Therefore,it is necessary to conduct in-depth research on the flow channel of the tube bundle structure in the heat exchanger,which can provide the professionals designing industrial equipment with accurate design parameters and provide sufficient assistance for the safe operation of the equipment.This paper studies the flow field around a gas-liquid two-phase fluid that rises vertically around a staggered cylindrical tube bundle.Numerical simulation methods are used to obtain the details of the flow field.The numerical simulation work uses the multiphase Euler Foam solver of OpenFOAM open source software and the simulation program composed of large eddy simulation k equation.First,by simulating the flow field of the rotating triangular tube bundle,and analyzing the results of the numerical simulation,it can be found that the gas-liquid two-phase fluid around the rotating triangle arranged cylindrical tube bundle has a stable time-averaged gas velocity distribution and time-averaged flow field.Gas fraction distribution.And through the comparison with the experiment,the credibility of the numerical simulation scheme used is verified.The entire flow field can be divided into the S-shaped main flow zone and the stagnation zone between the tube bundles.The stagnation zone is formed by the combined action of the stagnation point in front of the cylinder and the vortex behind the cylinder.There are many factors influencing the flow field of the tube bundle,mainly exploring the effects of different inlet flow rates,different inlet gas fractions,different initial gas phase diameters,and different staggered tube bundle arrangement forms on the tube bundle flow fieldWith the increase of the inlet flow rate,the time-average gas velocity in the Sshaped mainstream zone of the flow field increases,and the time-average gas velocity in the stagnant zone does not change much,but the vortex intensity increases.Therefore,the gas fraction in the S-shaped main flow zone increases,and the gas phase in the stagnant zone gathers toward the center of the vortex.The inlet flow velocity has little effect on the pressure distribution trend on the surface of the cylinder,but it will increase the pressure difference between the front and rear of the cylinder.The gas fraction has little effect on the distribution trend of the gas fraction in the flow field.The effect on the time-average gas velocity field is divided into two parts.It has a small effect on the distribution of the time-average velocity in the gas phase of the A and C sections,and has a small effect on the B and D sections.The influence of the time-averaged velocity distribution in the gas phase is relatively large.The pressure distribution before and after the cylinder tends to be stable with the increase of gas fraction,and the pressure difference before and after the cylinder decreases with the increase of gas fraction.The average particle size of the gas phase has a relatively large impact on the flow field.With the increase of the gas inlet particle size,the S-shaped mainstream area becomes larger and the stagnation area decreases.The mixing between gas and liquid begins to decrease,and the separation between gas and liquid becomes more and more obvious.The liquid area on the front of the cylinder increases,and the gas gathering area on the back of the cylinder decreases.The pressure on the surface of the cylinder is related to the distribution of the gas and liquid phases around the cylinder.Moreover,with the increase of the inlet gas particle size,the position where the vortex breaks away extends back to the cylinder.The arrangement has a great influence on the flow field velocity and gas fraction distribution,which can be said to completely change the flow field distribution.But on the whole,the distribution of gas and liquid phases still have the same characteristics.The gas phase is mostly concentrated in the vortex behind the cylinder.The boundary layer around the cylinder is basically the accumulation of liquid phases.There are only two gas phases behind the cylinder.The gathering area.