Influencing Factors On Flow Characteristics Of The Perforated Plate In A Balanced Flowmeter For Cryogenic Fluids

Due to the advantages of simplicity,reliability,high precision and low pressure drop,the balanced flowmeter has a promising application prospects in the field of cryogenic fluid flow measurement.As the critical throttling components,the perforated plate's structure and its flow characteristics under different application conditions will have a certain impact on the accuracy of flow measurement.In order to optimize the structure of the balanced flowmeter applied to cryogenic fluids,the following investigations were mainly carried out in this paper:1.Numerical simulation method to study the flow characteristics of the perforated plate.Based on the basic principle of perforated plate flow measurement,the relevant factors that influence the flow measurement were theoretically deduced and analyzed.On this basis,the computational models of numerical simulation were established.2.Influence of the perforated plate's structure.Flow characteristics of liquid nitrogen through the perforated plate with different structures were numerically investigated.The effect of each structural factor on the performance of the perforated plate was sorted out,which provides a theoretical reference for the optimization design of perforated plates.Simulation results reveal that the equivalent diameter ratio is the key influence factor of the pressure loss coefficient and stable region.The perforating form,such as the hole number,the hole diameter and the hole pitch,also has some influence on the discharge coefficient and pressure loss coefficient.Increasing the equivalent diameter ratio,the thickness or the chamfer can effectively improve the performance of the perforated plate.3.Influence of the perforated plate's application conditions.Flow characteristics of the perforated plate under different application conditions were numerically simulated to explore the stable working region of the balanced flowmeter.According to the simulation results,the discharge coefficient and the pressure loss coefficient in the stable region are not affected by the applied conditions.However,the Reynolds number range of the stable working region can be increased by increasing the pipe diameter,decreasing the inlet temperature or increasing the outlet pressure.Besides,the cavitation phenomenon has a certain effect on the discharge coefficient and pressure loss coefficient.When the Reynolds number is further increased,another stable region of the discharge coefficient will appear in the cavitation zone.