With the development of the gas-liquid two phase flow dynamics theory and the continuous improvement of two phase flowrate measurement requirements, the importance of slug flow research has become increasingly prominent. The wire mesh sensor (WMS), which consists of the perpendicular "cross-point" between the transmitting wires and receiving wires, forms a particular "hard field" measurement mode. This paper aims toinvestigate the measurement characteristics and accuracy of a 16×16-electrode conductivity WMS with a spatial resolution of 3.125 mm for gas-liquid two phase slug flow by means of flow experiments. Experimentswere performed in a 50 mm horizontal pipe with air and water as the working medium at atmospheric conditions, meanwhile, the time series data were collected by WMS. Comparing the cross sectional, a good correspondence can be found in the cross sectional direction between axial reconstructed images of fluid distribution and averaged void fraction time series. The WMS can realize the quantitative measurement of local void fraction and the qualitative spatial phase reconstruction of fluid distribution. Furthermore, distribution characteristics of the cross sectional averaged void fraction time series of gas-liquid two phase slug flow were analyzed. We found when superficial gas velocity is less than 3 m/s, the gas phase mainly exists in the form of elongate gas slug. When superficial gas velocity is around 5 m/s, it appears as typical bullet-shape gas slug. As superficial gas velocity increases to 10 m/s, the liquid slug becomes blurred and the gas phase almost penetrates through the liquid slug structures. In addition, a Probability Density Function (PDF) is generated from the instantaneous cross sectional averaged void fraction data for different flow regime conditions. The results show that the PDFs for lower superficial gas velocity case (3 m/s), two peaks in the void fraction signal are observed. Nevertheless, with an increase in superficial gas velocity, it is seen that the peak in the low void fraction region, which corresponds to the liquid slug structures, becomes much smaller even disappears.

This contribution describes a research of measurement uncertainty of industrial emissions flowing through vertical stacks and its dependence on different geometrical configurations and physical conditions. Since the legislative requirements for emission limits from industrial processes are decreasing, the higher measurement accuracy is becoming more important and new uncertainty standards needs to be implemented. Thiscontribution is a part of the research project 18NRM04 Heroes under European Metrology Program for Innovation and Research (EMPIR). CFD modelling is used to analyse particle distributions in stacks with three different geometries of a supply pipe, different size of the particles and several concentrations. Vertical stack with a circular cross section of a diameter of 0.75 m is considered with the supply pipe containing none, one or two bends. The number of particles entering the stack defines the initial volumetric concentration from 0.1 to 10 mg/m³ with the particle size from 10 to 50 µm.Concentration fields in several cross-sections were compared and the particle distributions were analysed as functions of the physical conditions and the chosen geometry of the stack. The results show not very high sensitivity of the concentration profiles on the initial concentrations. On the other hand, significant changes of the concentration fields are observed when the stack geometry or the particle diameter is changed. This should be taken into account in the iso-kinetic sampling practise where the overall concentrations are calculated from measurements in several points.

The measurement of liquid film parameters is of great significance in the momentum transfer and heat transfer characteristics of gas-liquid two phase in annular flow. The liquid film at the bottom of the horizontal annular flow is the thickest and produces the greatest influence on the nature of the annular flow. In large diameter horizontal pipes, the effect of pressure on liquid film behavior lacks systematic discussion. Therefore, a dynamic measurement system for annular flow liquid film was designed based on near-infrared(NIR) sensing technology to complete the measurement of annular flow liquid film thickness data under five pressures. The average liquid film thickness at the bottom is obtained by variational modal decomposition(VMD) of the time series signal, and the wave velocity parameter is obtained by mutual correlation velocimetry. The article initially discusses the effect of pressure on the average thickness of the bottom liquid film as well as the interfacial wave velocity.

Ultrasonic flowmeter is a velocity flowmeter, and its measurement accuracy is greatly affected by the flowfield in the pipeline. In the actual use process, due to the installation conditions are not ideal, the formation ofvortex flow, pulsating flow, asymmetric flow and other non-ideal flow field in the pipe, which in turn affects the accuracy of ultrasonic flowmeter. This study is based on CFD numerical simulation technology, 90° elbow, reducer, upstream and downstream flange diameter difference of one level and other typical disturbanceelements on the impact of the flow field in the pipe, simulate the flow field of the gas in the closed pipe after the disturbance elements, and calculate the resulting error, found that the impact of each disturbance element on the ultrasonic flowmeter measurement error increases with the increase in operating flow. For 90° elbow, the upstream and downstream flange diameter differ by one level, we use these two installation conditions to carry out real flow test, through the test data and simulation results for comparison and analysis, the results are consistent. At the same time, the use of experimental data on the simulation model correction, can guide the construction and transformation of ultrasonic flowmeter metering process, improve the accuracy of the measurement results, and effectively maintain the fairness of the trade handover.

With the ultrasonic flowmeter (Ultrasonic Flowmeter) in the natural gas metering is widely used, ultrasonic flowmeter accuracy is increasingly concerned. however, by the limitations of the calibration operation conditions, there aredifferences between the calibration operation conditions and actual operation conditions , and operation conditions on theimpact of ultrasonic flowmeter metering lack of systematic research, Wuhan branch station established a mobile natural gas metering standard device can be carried out in different pressure conditions of the gas transmission station calibration services.In this paper, we study the calibration tests carried out by the mobile natural gas metering standard device at different pressures, and through analyzing and integrating data, we derive the metering deviation caused by ultrasonic flowmeter under different working conditions, establish the mathematical model of Reynolds number error correction toguide the use of ultrasonic flowmeter, and eliminate the deviation introduced by the different operation conditions of calibration and use, improve the accuracy of trade measurement, while the research results can be the technical support for the revision of relevant standards and norms.