Numerical Simulation Reserach On Flow Stabilizing Effect Of The Surge Tank With Different Internal Structure

The performance parameters of various heat exchangers,valves and flow meters used in the fluid transmission and distribution network have a very important influence on the system operation process.When testing the performance parameters of these devices,the surge tank is a common pressure-stabilizing equipment used in the flow standard test,which has the function of reducing flow pulsation and attenuating pressure,so as to improve the accuracy and repeatability of the test results of the relevant device performance parameters.In this paper,the method of numerical simulation was used to study the influence of the internal structure parameters of the surge tank on the pressurestabilizing and flow stabilizing performance,which provided support for the product design of the surge tank and the selection of the location of the downstream pipeline flow measurement points.According to the similarity of the numerical simulation results and the flow fluctuation coefficient of the surge tank downstream pipeline in related experiment,the reliability of the numerical simulation method was verified.The transient numerical simulation on the gas-liquid two-phase pulsating flow was used to analyze the flow stability of the surge tank with the flow fluctuation as the evaluation index.The results showed that decreasing the aperture diameter of the horizontal partition is conducive to reducing turbulent viscosity in the outlet area and improving the flow stabilizing effect of the surge tank;when the vertical partition orifice is located at the lower part,the pulsating fluid entering the surge tank along the inlet pipe directly impacts the fluid in the outlet area through the orifice,which is not conducive to the flow stability.Therefore,it is appropriate to arrange the orifice at the upper part.The flow velocity distribution in the horizontal section of the front of the downstream pipe is symmetrically distributed,while in the longitudinal section a certain length of straight pipe section is still required to rectify in order to meet the uniformity.By analyzing the turbulent viscosity and flow velocity distribution of the surge tank and the downstream pipeline,the influence of the surge tank structure parameters on the flow stabilizing effect was studied.The structure parameters includes the amount of horizontal partition layers,aperture and spacing of the partition;and vertical partition position,orifice location and height.The simulation results showed that: for the surge tank in this example,it is better to arrange a two-layer horizontal partitions than the three-layer for flow stabilizing effect;Decreasing the aperture diameter of horizontal partition is conducive to reducing turbulent viscosity in the outlet area and improving the flow stabilizing effect of the surge tank;When the spacing between the horizontal partitions is 125 mm,the degree of fluid turbulence in the outlet area of the surge tank is smallest,and flow stabilizing effect is best;When the vertical partition is located D/3 away from the inlet of the surge tank,the flow stabilizing effect is best;When the orifice of the vertical partition is at the upper part,the flow stabilizing effect is better than that at the middle part;When the dimensionless height L/H of the vertical partition is 0.70,the flow stabilizing effect is best.The velocity distribution of the longitudinal section at the position of 10 times the diameter of the downstream pipe of the surge tank cannot be restored to the boundary condition of the axisymmetric distribution of the outlet section of the upstream pipe.If the surge tank is used to the relevant test system as a pressurestabilizing source,the measurement section where the flow sensor or other equipment to be tested should be installed at least 10 times the pipe diameter downstream.