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This paper introduces a kind of on-line calibration facility based on weighing method and master meter method, which can carry out the on-site and laboratory calibration of 35MPa/70MPa hydrogen dispenser. At first, the working principle and technical specifications of the hydrogen dispenser is explained. Then the working principle and design structure of the calibration facility is depicted. Finally, the calibration facility is used to perform the real flow calibration test on hydrogen dispenser. According to the test results, the expanded uncertainty of the calibration facility of master meter method is about 0.7% (k=2), and the expanded uncertainty of the calibration result is 0.96% (k=2); and the expanded uncertainty of calibration facility of weighing method is about 0.097% (k=2), and the expanded uncertainty of calibration result is 0.48% (k=2). The real flow test shows that the two method calibration facilities both can be used for actual calibration of 2.5-level hydrogen dispenser. The calibration facility of weighing method is suitable for the occasions with high accuracy requirements because of its short traceability chain, while the calibration facility of master meter method can be used for flexible on-line calibration because of its simple structure.

To solve the problems of secondary flow, turbulent vortex, and instability of the flow field in the elbow of the water flow standard device, some 3D geometric models of the elbow were established, and the flow field numeral calculations of the elbows were carried out based on the 3D models. The study shows that appropriately increasing the turning angle and the number of deflectors has a significant effect on improving the flow field quality in the elbow. While it is not obvious that the effect of increasing the thickness of the deflector on the flow field quality, and which may increase the requirements for the power source of the standard device. It is concluded that the elbow with a 135°turning angle and 2 pieces deflectors may be the optimal choice.