Flow Metrology Research Articles

Dynamics of physical flows measured by positron emission techniques

Short lived positron emitting species are used to produce flow-following tracer particles to study flow dynamics in a technique known as positron emission particle tracking (PEPT). The photon pairs produced by positron annihilation are detected in time coincidence by arrays of high-speed position sensitive detectors. Reconstruction of consecutive annihilations are used to determine the near-instantaneous position of the tracer particle. Hence, the resulting bulk flow dynamics are derived, including residence times, velocities, accelerations, and related kinematic properties. The Department of Physics at the University of Cape Town uses PEPT to study dynamic physical processes, turbulent, and multiphase flows. Studies aim to address global challenge topics including problems in water scarce environments, reducing industrial wastes, and enhancing developments towards sustainable economies through improved process efficiencies and design led approaches. The PEPT Cape Town enterprise is discussed, including the development of flow metrology systems and complementary nuclear measurement techniques. Research encompasses four key themes: radioisotope tracer production, instrumentation & detector development, data acquisition & processing, and flow metrology.

CFD Model of a Mechanical Oscillator Flowmeter

Most of the studies on mechanical oscillator flowmeters were conducted in the '80s and '90s when computational fluid dynamics (CFD) was not a viable scientific tool in flow metrology. Still, many topics related to the application of mechanical oscillator flowmeters require further investigation. In the article, a numerical model of a mechanical oscillator flowmeter is developed with the commercial software ANSYS Fluent. The model is validated against experimental data obtained at a water calibration stand. The influence of the selected turbulence model, dynamic mesh method, as well as grid and time step size is studied. The model's qualitative behavior is correct, allowing investigation into the flowmeter operation in detail. It can provide a base for the improvement of the flowmeter's performance. Relative differences in the frequency of oscillations did not exceed 4% for a DN50 flowmeter in the flow rate range (2-40) m3/h.

Towards a new transfer standard for speed of sound measurements in liquids at cryogenic temperatures

Traceability of fluid flow measurement is a prerequisite for the accurate determination of transferred mass, heat and energy. However, considering the wide range of flow-rates, temperature, pressure, viscosity and densities, which is of interest for practical applications of fluid flow metrology, the accurate calibration of ultrasonic flow meters still represents a demanding task. Alternative to the usual gravimetric calibration, the possibility to provide traceability through using a speed of sound standard has been less explored. In this work, we describe and discuss the performance of an ultrasonic cell, and the feasibility of using this sensor to provide traceable measurements of the speed of sound. The instrument has been designed to serve as transfer standard for speed of sound and, its features make it suitable for the calibration of ultrasonic flowmeters both in the laboratory and on industrial pipelines. The sensor has been tested by performing speed of sound measurements in liquid methane between 100 K and 162 K and for pressure up to 10 MPa. The expanded relative uncertainty (k=2) of the speed of sound w is Ur(w)=0.15% for temperature below 130 K and Ur(w)=0.32% above 130 K. The obtained results are found in agreement with previously published measurements and with the predictions of the Setzmann and Wagner and GERG equations of state. Along with the results of speed of sound measurements and their expanded (k=2) uncertainty, we provide a detailed discussion of the procedures adopted to improve the stability of the sensor, and the specific corrections applied considering the cryogenic working conditions.

Investigating reproducibility in multiphase flow metrology: Results from an intercomparison of laboratories

This paper presents the results of an intercomparison of multiphase flow laboratories. Conducted as part of EMPIR project 16ENG07 – MultiFlowMet II, the primary focus of the investigation was to determine the influence of laboratory-specific factors on the reproducibility of measurements made by multiphase flow metres (MPFMs). To minimise these effects as much as possible, a portable transfer package was designed, including the MPFM, a transparent viewing section, and a straight pipe section with a length of 100 internal pipe diameters. A reproducibility parameter, ζ, was developed to quantify both the reproducibility of the transfer package. Across the three laboratories, metrological compatibility was achieved for the majority of test points. By presenting the ζ values as functions of the gas volume fraction (GVF) and water liquid ratio (WLR), it was possible to identify flow regimes that may be more susceptible to reductions in reproducibility.

Influence of neodymium magnet field on fuel gas metering with diaphragm gas meters

The article deals with the problem of illegal fuel gas consumption among individual consumers in households, especially with regard to gas theft using neodymium magnets attached to diaphragm gas meters. First, the author presents a historical outline of the use of neodymium magnets for the purpose of illegal consumption of fuel gas. The current legal status regarding the requirements for gas meters resistance to tampering and the activities of the Oil and Gas Institute – National Research Institute (INiG – PIB) and Distribution System Operators aimed at eliminating the possibility of illegal gas consumption with the use of neodymium magnets were discussed. Currently possible methods of confirming gas theft using gas meters exposed to the magnetic field of neodymium magnets were presented. Next, the methods of performing at the INiG – PIB laboratory expert examinations of gas meters suspected to be used for illegal gas consumption after their removal from the distribution network were described, and the criteria for assessing these gas meters were given. Based on the expert examinations of gas meters carried out at the Laboratory of Flow Metrology INiG – PIB in the years 2006–2020, a summary of the share of gas meters tampered with the use of neodymium magnets and gas meters with an increased remanence level was presented in relation to performed in a given year expert examinations of gas meters suspected to be used for illegal gas consumption. The methods of counteracting the theft of fuel gas with diaphragm gas meters tampered with the use of neodymium magnets were shown. It has been proved that at present the EC type examination certificate (MID Directive) and the certificate of compliance with the requirements of EN 1359 or OIML R 137-1 & 2 specification do not confirm gas meters resistance to gas theft involving the use of a strong magnetic field. Requirements for new diaphragm gas meters in terms of their resistance to neodymium magnets were presented, and updated criteria for the evaluation of the test results of gas meters exposed to these magnets were given. Finally, a conclusion was proposed regarding the necessity to include provisions on the resistance of diaphragm gas meters to magnetic field in the relevant normative documents for gas meters in order to provide a systemic safeguard for the parties to fuel gas supply contracts.

Model and Simulation Studies of the Method for Optimization of Dynamic Properties of Tachometric Anemometers.

Mechanical tachometric anemometers, based on the phenomenon of the exchange of momentum between the flow and rotating measuring element, represent an important class of instruments used in flow metrology. In particular, they are used in meteorological and ventilation measurements. Mechanical anemometers with rotating measuring element are, however, known for their drawback related to their poor dynamic properties resulting from relatively large dimensions and mechanical inertia of the measuring element. In these instruments, the phenomenon of overestimating the measured average velocity caused by the inertia of the rotor takes place. Optimization of the dynamics of the measurement process, as well as the estimation and minimization of the measurement uncertainty, can be performed based on mathematical model of anemometer. In this study, a new, original concept of optimization of dynamic properties of tachometric anemometers is proposed, and the results of model and simulation studies are presented. The new concept of measuring instrument is based on the use of feedback and active control of the rotor. The new method was tested using model research, where two types of flow velocity excitations were applied: sinusoidal and rectangular. The tests carried out showed that the developed method allows for minimization of the dynamic uncertainty of the measurement and minimizes the phenomenon of average flow velocity overestimation occurring in time-varying flows. It has been shown that the use of optimization system allows for approximately tenfold reduction of the error of average velocity measurement in the case of pulsating flows. In addition, the optimization systems allow for anemometer’s transmission bandwidth to be extended about a hundred times. This creates new application possibilities for these instruments and allows for a large reduction of measurement uncertainty.

Validation of simulations in multiphase flow metrology by comparison with experimental video observations

One important task in flow metrology is to evaluate the uncertainty in multiphase flow metering. A first important step towards this goal is to establish an accurate computational fluid dynamics (CFD) model of multiphase flows. In this contribution, results of multiphase flow simulations are validated by comparison with experimental data. For the evaluation and quantification of experimental observations, a tool for video analysis has been implemented. This tool extracts the liquid level over time, which is then used for further analysis and comparison with simulation data. Additional relevant parameters are obtained by frequency analysis, which is applied to both, experimental and simulation data. A comparison of the results shows good agreement between experiment and simulation.

An alternative mathematical model of vane anemometers based on the balance of power

Anemometers based on the exchange of momentum between the flow and rotating measuring element comprise an important class of instruments used in flow metrology, especially in meteorological and ventilation measurements. In these instruments, overvaluation of the measured average velocity, caused by the inertia of their rotors, takes place. To analyse this phenomenon and the dynamics of the measurement process, as well as to estimate and minimize the measurement uncertainty, it is required to be acquainted with the mathematical model of the anemometer. In this study, the model of the vane anemometer based on the equation of motion of its rotor available in the literature is analysed, and a new model based on the power balance is proposed. Model testing and a comparison of both models has also been performed.

Optimization of the generation of temperature waves in flow metrology

ABSTRACTTemperature waves are used in metrology to determine flow velocities, as well as the coefficient of thermal diffusion, chemical composition, and other parameters of the flowing medium. This study presents a method for precise generation of temperature waves in flows, based on digitally controlled electronic system. A mathematical model and structure of the system implementing the method is described. The system consists of a wire temperature wave transmitter, supplied by the system setting the preset temperature function in time. The mathematical model of such system, together with results of model and optimization testing are presented. The system allows one to generate temperature waves of the shape preset by a digital signal, generated by a computer-based control system. Such a system may be used in analytical instrumentation.

New multi-million pound flow metrology programme for TUV NEL to include carbon capture and other emerging technologies

New multi-million pound flow metrology programme for TUV NEL to include carbon capture and other emerging technologies

Three-dimensional particle imaging by defocusing method with an annular aperture

We propose an annular-aperture-based defocusing technique for three-dimensional (3D) particle metrology from a single camera view. This simple configuration has high optical efficiency and the ability to deal with overlapped defocused images. Initial results show that an uncertainty in depth of 23 microm can be achieved over a range of 10 mm for macroscopic systems. This method can also be applied in microscopy for the measurement of fluorescently doped microparticles, thus providing a promising solution for 3D flow metrology at both macroscales and microscales.

The effects of rheological and wetting properties on underfill filler settling and flow voids in flip chip packages

As the bump diameter and bump pitch of flip chip packages get smaller, the underfill becomes more resistant to flow. Therefore, low viscosity underfills are used in the process to increase the throughput. Problems associated with low viscosity underfills include filler settling and flow induced voids due to fast edge flow. In this paper, we will discuss how the rheological properties can affect underfill filler settling and flow voids. The effects of yield stress of underfill on filler settling and the effects of shear thickening of underfill at large shear rates on flow voids of underfill were investigated. It was shown that the underfills with small fillers have shear-thickening viscosity and yield stress. The filler settling of underfills with yield stress was greatly reduced. A video underfill flow metrology with quartz die packages was developed for flow void observation. The correlation between underfill, substrate properties, and flow voids formation based on the video underfill flow measurement will be discussed.

Final report on the CIPM key comparisons for compressed air and nitrogenconducted in November 2004/June 2005: CCM.FF-5.b

The calibration of gas meters for flow rate measurements of natural gas at high pressure is of critical importance for gas importers, gas distributors and international trade. It is recommended to calibrate gas meters actually with natural gas at high pressure; however, some countries apply compressed air or nitrogen as a surrogate fluid.Key comparisons (KCs) have been organized among all national metrology organizations (NMIs) worldwide that maintain national standards and take care of compressed air/nitrogen flow metrology. It turned out that, for the time being, only four NMIs were ready to participate, as no other NMIs or countries maintain national standards. These four NMIs are LNE in Paris, NEL in Great Britain, CMS/ITRI in Chinese Taipei, and KRISS in Korea. PTB-pigsar in Germany has been used as the pilot lab for the initial calibration of the transfer standard.All existing facilities in the world were invited to participate, but they all refrained from participation, as they are not yet ready, e.g. CEESI, SwRI, NIST. Russia does not maintain a calibration facility for this type of fluid flow so far. For more details we refer to the full report.The KC for compressed air was conducted during November 2004/June 2005 successfully at flow rates over a wide overlapping range of flow rate and pressure using a set of turbine meters. The transfer package comprises of two turbine meters put in series. Flow rates between 65 m3/h and 1000 m3/h and pressures between 5 bar and 40 bar have been applied.It shall be mentioned here that the weighted average for the KCRV according to a BIPM recommendation for KCs has been used as the first choice. The final report presents the degree of equivalence among the participants as well as the degree of equivalence to the KCRV and confirms all claimed uncertainties of the national calibration facilities of France, Great Britain, Korea and Chinese Taipei. In addition, a link to CCM.FF-K5a for natural gas can be made. Quantitative En values for the degree of equivalence of all participants referred to the KCRV as well as the degree of equivalence among the participating NMIs have been reported too.It turned out that all claimed uncertainties of the calibration and measuring capabilities of the participating facilities could be confirmed.Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

A mathematical model of the self-averaging Pitot tube: A mathematical model of a flow sensor

Flowmeters with self-averaging Pitot tubes are more and more often applied in practice. Their advantages are practically no additional flow losses, usability in the case of high temperature of fluids and simplicity of fitting. A mathematical model of a self-averaging Pitot tube including the influence of the probe shape, selected constructional features and flow conditions on the quantity of differential pressure gained has been given in this paper. The values and ranges of variations of the coefficients established for the model have been assessed on the basis of the numerically computed velocity and pressure fields around and inside the probe. Velocity and pressure fields were calculated by means of solving conservation equation and turbulence models. The characteristics linking values of the flow coefficient with values of the Reynolds number have been presented. The conclusions have been formulated taking flow metrology needs into account.

All-Union Conference on flow metrology

All-Union Conference on flow metrology