## IMEKO Event Proceedings Search

Page 12 of 907 Results 111 - 120 of 9067

**Insertion Depth Effect for Vane Anemometers**

In this paper we show that velocity indication of a vane anemometer in a wind tunnel can significantly and non-trivially depend on length of the part of the anemometer’s mounting rod which is exposed to flow – the so-called insertion depth. The insertion depth dependencies for four vane anemometers with various dimensions are presented. For a small size vane anemometer with a propeller diameter of 22 mm, for example, a change of the insertion depth by 10 cm can cause a reading variation by up to 5 % - a value which is an order of magnitude larger than a typical expanded uncertainty of calibration in wind speed laboratories of national metrology institutes. Therefore, this effect has important consequences for selection of transfer standards for interlaboratory comparisons, since each participant can have a different insertion depth value, and also for the calibration practice where possible differences between the insertion depth of the user and the calibration laboratory should be taken into account.

**clamp-on AND transit time difference AND smart meter**

A new, miniature design of a clamp-on ultrasonic transit-time difference flow meter for use in liquids is presented, with particular application to small diameter, thin walled metal pipes, opening up new areas of application, including smart water metering. The particular embodiment of the hardware is low cost and can be installed by unskilled users, and uses a type of guided wave mode that is significantly different to previous examples of clamp-on flowmeters that have used a leaky guided wave in the pipe to generate compression waves in the liquid. In the example presented in this paper, the entire liquid-pipe system acts as a wave guide, providing large amplitude ultrasonic signals with outstanding signal to noise, even from a drive voltage of just a few volts. The flowmeter is capable of measuring flow rates down to a few millilitres per second, with an accuracy better than 0.5 millilitres per second. The results presented mainly focus on 15 mm diameter copper pipes of wall thickness 0.7 mm, but the same approach works well on pipes with larger diameters and slightly thicker walls, up to around 30mm diameter in the current embodiment, In many instances, in previous work, the presence of the guided wave modes has prevented clear interpretation of the ultrasonic signals that are detected.

**The research on discharge coefficient of a non-standard Venturi meter with a swirler**

Flow measurement plays an important role in the modern engineering field. And flow rate is one of the mostimportant parameter in this process. One traditional method of deriving flow rate is measuring the pressure difference (DP) along the pipe while the concerned fluid flowing through a DP instrument, such as Venturi meter. This DP instrument is among the most widely used flow measurement instruments, available inplumbing, energy transport pipeline, petroleum chemical industries, etc.In this research, a non-standard Venturi structure is proposed to satisfy the measurement demand of the inlet multi-phase flow with complex flow pattern. Compared to the standard Venturi meter,the angles of the divergent and the convergent of the proposed device are changed to obtain a shorter pipeline. Besides, a swirler is also placed into the convergent, which would force the flow to swirl with tangential velocity and adjust the inlet gas-liquid two phase flow to annular flow. The focus of the study is directed toward the pressure profile and the discharge coefficient Cd of the proposed structure. Computational simulation of single phase flow is carried out to measure the pressure drop along x- axis via FLUENT. According to the simulation results, the addition of swirler brings an extra pressure drop in advance. At the end of the throat, there is a sudden drop of pressure, decreasing to the lowest point, which is caused by the characteristics of the precession vortex. Then the final static pressure value is obviously lower than the initial static pressure value.

**Water holdup measurement of oil–water two-phase flow using dual-mode microwave method**

Water cut is one of the key parameters in the process of oil and gas production. In the present study, wepropose a microwave resonant cavity sensor(MRCS) which can work in both TM010 and TM110 modes, andestablished a water cut measurement of vertical upward oil–water two-phase flow in the range of 0-100 %. The response characteristics of the two resonant modes to water cut are analyzed by the coupling simulation offlow field and electromagnetic field using COMSOL finite element simulation software. A flow experimentisconducted with the designed MRCS measurement system. The sensitivity of the two modes resonantfrequency in different water holdup range is compared. The results show that 95 % of the experimental points’ relative errors is less than ± 5 %.It is indicated that the model can predict water hold with high accuracy, which may provide a solution for wellhead water cut measurement of oil field.

**A Void Fraction Measurement Method of Gas-water Flow Based on Microwave Method**

In the natural gas industry, measuring void fraction with high accuracy is challenging, because the flow pattern of gas-flow is complicated and changeable. This research presents a microwave sensor to measure void fraction of gas-water flow based on the microwave transmission line method. The sensor contains horizontal and vertical electrodes resulting in a spatial orthogonal transmission line combination structure, so that the gas-water flow regime can be detected and its influence on the measurement can be accounted for. The electromagnetic fields inside the sensor for stratified and annular distribution structure are simulated and analyzed using COMSOL software. Furthermore, the variation characteristics of the horizontal and vertical electrode phase outputs of the stratified distribution structure are investigated by static experiments. Finally, flow experiments covering stratified, wavy, slug, annular gas-water flow regimes, indicates that the void fraction are positive correlated to the sensor outputs and can be predict by the sensor.

**Experimental Investigation on Measurement Characteristics of WMS for Gas-Liquid Slug Flow**

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.

**Optimization of electrode and contraction section of 90° bent electromagnetic flowmeter using CFD simulation**

Currently, electromagnetic flowmeters must typically be inserted into a straight pipe, which usually requires a larger installation space. To improve installation adaptability, a novel 90° bent electromagnetic flowmeter is proposed. As the measurement signal of the electromagnetic flowmeter is closely related to the flow state of its internal fluid, a large-eddy simulation (LES) was used to study the influence of the shape of the electrode and the contraction section of the flowmeter on the flow characteristics inside the flowmeter to reveal the relationship between them along with the measurement accuracy. A comparison between the numerical results and the experimental results was also performed. The velocity fluctuations of the monitoring points around the cone and flat electrodes were compared, and it was found that the overall measurement error of the cone electrodes was smaller than that of the flat electrodes. The experimental results showed that the pulsation of the voltage signal measured from the cone electrode is smaller than that of the flat electrode. In addition, the absolute value of the error in the small flowrate is much smaller than that of the flat electrode. Consequently, the measurement performance of the cone electrode is better. In addition, the largest velocity fluctuation occurred between the electrode wall and tube wall, indicating that installing the coil should avoid exciting strong magnetic fields here.

**Modelling of uncertainties of an emission concentration measurement in stacks**

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.

**Void fraction measurement based on electromagnetic wave sensor**

Gas-liquid two-phase flow is an unavoidable energy flow phenomenon in industries, and void fraction measurement is a crucial challenge in the two-phase flow. In the study, the coaxial line phase sensor is designed base on electromagnetic wave transmission principle, by which void fraction of the slug and stratified flow was acquired. The void fraction measured by new coaxial has a well time-domain and Probability Density Functions (PDF) distribution characteristics, four typical models with different physical backgrounds were selected to evaluate the measured values of the sensors. The mean absolute errors (MAPE) were 7.85 %, 24.41 %, 7.22 %, and 15.44 % for slug flow, and 12.31 %, 6.46 %, 12.68 %, and 2.95 % for stratified flow. The results indicated that the coaxial line phase sensor has well measurement accuracy and not limited by the flow regime.

**Effect of System Pressure on Liquid Film Behavior in Horizontal Annular Flow**

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.

Page 12 of 907 Results 111 - 120 of 9067