Research on Piston Gas Flow Device Based on P-V Automatic Adjustment
To research the flow characteristics and differences between ultrasonic and thermal gas meters under the conditions of air medium and natural gas medium,a piston gas cycle flow standard device based on pressure-volume(P-V)automatic adjustment is designed.The basic architecture and working principle of the device are introduced.The reasons affecting the measurement accuracy in the closed loop of fluid flow are analyzed.A mathematical model of P-V automatic adjustment control for realizing constant flow is established.The device adopts an active disk-shaped piston flow standard with volume expansion uncertainty Ur=0.07％;configures a column-shaped piston as volume compensation,and adjusts the direction and speed of the piston movement by monitoring the change of gas pressure to achieve the purpose of constant pressure.The device is equipped with a six-meter station work bench,with a maximum working pressure of 0.1 MPa,a maximum flow rate of 10 m3/h,and a range ratio of 1 000∶1;by testing six G2.5 ultrasonic gas meters,the pressure fluctuation obtained is less than 5 Pa,and the stability of flow rate is better than 0.02％.In the field of flow testing,the P-V automatic adjustment method can provide a new solution idea for realizing constant flow.
MetrologyGas meter detectionPiston gas flow standard devicePressure-volume(P-V)automatic adjustmentFlow stabilityConstant flow
NETL
NSTL
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