Abstract
The application of particle image velocimetry (PIV) technology for monitoring natural gas flow is a new method of flow measurement. Since the principle of this technology was proposed, there are still some potential issues. This article investigates the influence of a manifold structure on the measurement results of a PIV flowmeter. A comparison is performed between concentric and eccentric manifold structures, using a circular straight pipe as reference, in terms of the measurement error of the PIV flowmeter and the internal flow state of the natural gas. The results demonstrate that the manifold structure significantly affects the measurement reliability of the PIV flowmeter, especially the eccentric manifold structure. Under flow conditions ranging from 100 to 600 m3/h, the maximum measurement errors caused by the concentric and eccentric manifold structures are 2.49% and 3.05%, respectively, which show a noticeable increase compared to the maximum measurement error of 2.08% observed for the circular straight pipe. Additionally, the influence of the manifold structure on the downstream flow field is also evident, as the eccentric manifold structure increases the turbulence intensity of the downstream fluid by nearly twofold. The addition of a rectifier can effectively improve the flow state and enhance the measurement reliability of the PIV flowmeter. For the concentric manifold structure under the condition of a 600 m3/h flow rate, the inclusion of a rectifier produces highly accurate measurement results, similar to those obtained by an ultrasonic flowmeter, with an error value close to zero. This study provides technical support for further promoting the practical application of PIV flowmeters.