Study On Numerical Simulation Of Flow And Measurement Error Characteristics Of A Diaphragm Gas Meter

Diaphragm gas meter is a flow measurement meter which uses flexible thin measuring chamber to measure the gas volume, with advantages like stable measurement performance, wide measurement range etc., and is very suitable for low pressure and small flow rate measurement. It is widely used in household and commercial gas pipelines and natural gas consumption measurement. Experiment and theory methods are usually used on studying diaphragm gas meter, but numerical simulation method is rarely used. CFD method on study the gas meter’s internal flow filed, pressure loss and measurement error of the diaphragm meter has been proposed and demonstrated. Main works and results are as follows:1. Dynamic numerical simulation of internal flow has been realized. Several technical problems have been resolved, including linkage relationship between the rotary valve and the diaphragms, realizing and controlling the movements of the rotary valve and the diaphragms with computer program. Dynamic simulations of diaphragm gas meter have been carried out by using the sliding mesh, moving mesh and UDF techniques. According to calculations, velocity streamlines and pressure distribution chart of the gas meter have been get.2. Measurement error has been analyzed. For the research on measurement performance, by numerical simulation of flow field, with the inlet flow from 0.267m3?h-1 to 4m3?h-1, at a condition of the rotary valve and valve seat gap of 1mm, measurement error and pressure loss could be obtained. By comparing analysis results of the experimental data, two trends were consistent and comply with the actual situation. Based on experimental data and theoretical analysis of the measurement error and pressure loss, relation curve between them could be established.3. The impact of motor valve on the diaphragm gas meter flow has also be investigated. For the measurement performance, by the numerical simulation of the flow field, with the same flow of inlet, measurement error and pressure loss could be obtained. With the increase opening of motor valve, measurement error and pressure loss decreased. The pressure loss has been small and stable when the valve ranges from 6.9 to 10.9mm.