Flow Measurement Method Research Articles

Spatiotemporal laser speckle flowmetry based on elastic-walled U-shaped tubing apparatus: optical method for urinary flow measurement

We propose an optical method for uroflowmetry, exploiting the laser speckle contrast imaging (LSCI) technique onto an intermediate tubing apparatus having an elastic wall that can sensitively respond to flow-induced shedding vortices. Based on the method, we devised and fabricated an elastic-walled U-shaped tubing apparatus (EWUSTA), using the three-dimensional printing technique. We utilized the spatiotemporal contrast scheme for the LSCI as a fast and reliable computational algorithm. We investigated three different materials of flex-vinyl, ninja-flex, and natural rubber latex for the elastic wall of the EWUSTA in steady flow conditions, and verified that their optimal operational ranges could extend up to 7, 15, and 25 ml/s, respectively. We characterized the natural-rubber-latex-based EWUSTA in dynamic flow conditions in comparison with a commercial reservoir-weight-transducer-based gravimetric flowmeter, and verified its feasibility. We stress that the proposed method can offer precise and accurate information on flow dynamics. In addition, we found that the upper limit of the optimal operational range of the proposed apparatus had strong correlation with the tensile strength of the elastic-wall material. We reckon that the proposed and demonstrated method has great potential not only for uroflowmetry but also for other flow-related medical and industrial applications.

Two-dimensional flow visualization and velocity measurement in natural convection near indoor heated surfaces using a thermal image velocimetry method

Indoor velocity measurement techniques are categorized into point-wise and global-wise measurement techniques. Currently, measurements are either intrusive or restricted to the measurement area. This study presents a thermal image velocimetry (TIV)-based flow measurement method that is suitable for visualizing indoor two-dimensional velocity fields near indoor heated surfaces. The proposed technique uses only an infrared camera for mapping the surface temperature fluctuations. Image processing steps that are used to recover the velocity distribution include the decomposition of the video files into individual frames, the application of filtering to remove background noise, cross-calculation to estimate the velocity, and a final velocity correction based on the continuity equation. To investigate the feasibility of this method, natural convection was studied close to a heated vertical surface in a rectangular cavity. Thermal image velocimetry and particle image velocimetry (PIV) were used to visualize the flow field above a heating unit. The results indicate that the airflow field can be visualized by TIV, and the results measured by TIV are shown to be similar to those for the surface of 6 mm away from the heated surface measured by PIV. A linear correlation is established between TIV and PIV.

Transient process based electromagnetic flow measurement methods and implementation.

The ordinary electromagnetic flowmeter (EMF) utilizes the steady-state period of the excitation current for measuring the flow rate in order to ensure zero stability and measurement accuracy. In this paper, the transient process of EMF is studied to measure the flow rate so as to realize applications requiring ultra-low power consumption, for example, water meters. For this reason, the dynamic excitation current and signal voltage of the transient process are analyzed, and three kinds of transient measurement methods are proposed to determine the relationship between the processing results of the signal voltage and flow rates. They are the voltage-current ratio method, voltage-current differential method, and differential interference compensation method. In order to verify these measurement methods, a DSP (Digital Signal Processor) that is the same processing chip as the current ordinary electromagnetic flow transmitter is selected to design a hardware system of the transmitter, and the excitation current and signal voltage of the transient process are acquired. Analysis of experimental data shows that there is a good linear relationship between the processing results of the signal voltage and flow rates. The software of the electromagnetic flow transmitter based on DSP is developed, and the transient measurement methods are realized in real time so as to perform the water flow calibration experiments and power consumption tests. The experimental results show that the measurement accuracy is 0.5% which is the same as the ordinary EMF. Comparisons of power consumption show that the excitation power consumption of EMF based on the transient measurement principle is 1/1200 of that of the ordinary EMF.

Design and measurement methods for a lithium vapor box similarity experiment.

The lithium vapor box divertor is a concept for handling the extreme divertor heat fluxes in magnetic fusion devices. In a baffled slot divertor, plasma interacts with a dense cloud of Li vapor which radiates and cools the plasma, leading to recombination and detachment. Before testing on a tokamak, the concept should be validated: we plan to study detachment and heat redistribution by a Li vapor cloud in laboratory experiments. Mass changes and temperatures are measured to validate a direct simulation Monte Carlo model of neutral Li. The initial experiment involves a 5 cm diameter steel box containing 10 g of Li held at 650 °C as vapor flows out a wide nozzle into a similarly sized box at a lower temperature. Diagnosis is made challenging by the required material compatibility with lithium vapor. Vapor pressure is a steep function of temperature, so to validate mass flow models to within 10%, absolute temperature to within 4.5 K is required. The apparatus is designed to be used with an analytical balance to determine mass transport. Details of the apparatus and methods of temperature and mass flow measurements are presented.

High-performance approach for estimating stage-discharge curves in the open channels

The stage-discharge relationship is one of the frequently used methods for continuous river flow measurement. In the management of water resources and flood control, the accuracy of the rating curve is a key priority. Various methods have been proposed for estimating the stage-discharge curves in open channels, including the model of Ahmadi et al. (2017) in which the rating curve was identified by utilizing the information of discharge at a referenced water level. In the present study, a novel approach was taken to improve that model by modifying its basic assumptions and employing multi-objective optimization. To this end, multivariate relationships were presented to determine the actual mean velocity in the flow cross-section. The unknown exponents of the proposed relationships were obtained by using the second version of the Strength Pareto Evolutionary Algorithm (SPEA2), and the appropriate equation was selected by applying the TOPSIS (Technique for Order Preferences by Similarity to an Ideal Solution) approach. The validity of the proposed method was assessed across 6 artificial and 6 natural hydraulic cross-sections. Results showed a close agreement between the estimated and observed data. In the next step, the results of the proposed method were compared with those of the previous model using the Mann-Whitney U test. The results demonstrated that the proposed model was more efficient than the previous one.

A practical approach to use the thermodynamic efficiency method for flow measurements

The thermodynamic efficiency method represents the most accurate technique to measure the efficiency of hydraulic machines exceeding 1 kJ/kg of specific energy. On large-scale machines, it is common to use this method also to measure the discharge by simultaneous measurement of the mechanical power. This is either done iteratively or by the use of analytical solutions for simple test setups. We present here an extension of these analytical solutions to arbitrary test setups and conditions, which appear in practical applications. A sign convention has been introduced to harmonize relevant test codes, which deal with performance testing of hydraulic turbines and pumps, in the future.

Flow rate measurement in stacks with cyclonic flow – Error estimations using CFD modelling

Two methods of flow measurement in stacks are investigated to determine their errors in presence of cyclonic flow. One method – based on velocity measurements with a Pitot tube in a grid of points – is the standard reference method according to EN ISO 16911-1. The second method – ultrasonic flow measurement – is often used as the automated measurement system in stacks according to EN ISO 16911-2. Several typical stack configurations are considered and the flow field in the stacks is obtained using validated computational fluid dynamics (CFD) modelling with OpenFoam software. We show that possible errors of the standard reference method due to the cyclonic flow are significant compared to the requirements of the EU’s Emissions Trading System. For the ultrasonic flow meter we compare various configurations (number, orientation, position) of the ultrasound beams and we demonstrate the flow profile pre-investigation by CFD as prescribed in section 8.3 of EN ISO 16911-2.

PIV measurement of cross flow in a rod bundle assisted by telecentric optics and matched index of refraction

Spacer grids induce local flow disturbance in fuel assembly including lateral cross flow and elevated turbulence fluctuation. In order to investigate the cross flow downstream of spacer grids and to provide the high-fidelity data for the CFD validation of rod bundle flow, a flow measurement method has been proposed to measure the flow in the full cross section of the 5 × 5 rod bundle. A two-dimensional (2D) particle image velocimetry (PIV) system is utilized for the flow measurement. A telecentric lens is employed to minimize the perspective angle when the CCD camera is located distant from the measured cross section. The matched refractive index technique is also introduced to eliminate the non-uniform laser illumination behind the rods which is resulted from the laser refraction on the convex rod surface. Such configuration is examined for the cross flow measurement of a 5 × 5 rod bundle in a small scale test facility. It has been shown that the cross flow pattern can be well depicted in the entire cross section when the measuring plane is within 10 Dh downstream of a spacer grid. The obtained distribution of sampled flow velocity appears in good agreement with the normal distribution.

Using Laser Doppler Imaging and Monitoring to Analyze Spinal Cord Microcirculation in Rat.

Laser Doppler flowmetry (LDF) is a noninvasive method for blood flow (BF) measurement, which makes it preferable for measuring microcirculatory alterations of the spinal cord. In this article, our goal was to use both Laser Doppler imaging and monitoring to analyze the change of BF after spinal cord injury. Both the laser Doppler image scanner and the probe/monitor were being employed to obtain each readout. The data of LDPI provided a local distribution of BF, which gave an overview of perfusion around the injury site and made it accessible for comparative analysis of BF among different locations. By intensely measuring the probing area over a period of time, a combined probe was used to simultaneously measure the BF and oxygen saturation of the spinal cord, showing overall spinal cord perfusion and oxygen supply. LDF itself has a few limitations, such as relative flux, sensitivity to movement, and biological zero signal. However, the technology has been applied in clinical and experimental study due to its simple setup and rapid measurement of BF.

Uncertainty estimates of tracer gas dilution flow measurements in large-scale exhaust ducts

Accurate measurements of volume or mass flow in large conduits can be difficult to achieve due to non-ideal flow characteristics such as asymmetry of the velocity profile and off-axis flow components due to swirl. The tracer gas dilution method is independent of these and other non-ideal flow characteristics, but relies on the conservation and uniform mixing of the tracer. This study demonstrates the application of the tracer gas dilution method to measure the volume flow in a large-scale exhaust duct used for flue gas venting. The estimated measurement uncertainty was less than ± 3.5% and considered contributions from instrumentation, degree of mixing, and repeatability of the method. This level of uncertainty demonstrates that the method can be applied as an independent comparison or quality check for other flow measurement methods in large exhaust ducts or flow conduits.

High-precision Ultrasonic Flowmeter for Mining Applications based on Velocity-area

The flowmeter is widely used in coal mining because of its higher measurement precision and simple installation without channel project modification. In this paper, a flow measurement method based on velocity-area is investigated, and a functional flowmeter for mining applications with higher precision is designed. The two key parameters, the liquid level and flow velocity are required to be obtained for achieving the proposed method. The proposed flowmeter is composed of three main functional modules: (1) flow velocity detection module based on ultrasonic time difference method, (2) liquid level detection module, and (3) mud level detection module based on ultrasonic pulse echo method. All the measured data are transferred to the monitoring station for analysis and displayed in real-time through M-BUS. The flowmeter is designed focusing on mining applications, and has higher benefits for preventing water disasters in coal mines

Hybrid PET/MRI imaging in healthy unsedated newborn infants with quantitative rCBF measurements using 15O-water PET

In this study, a new hybrid PET/MRI method for quantitative regional cerebral blood flow (rCBF) measurements in healthy newborn infants was assessed and the low values of rCBF in white matter previously obtained by arterial spin labeling (ASL) were tested. Four healthy full-term newborn subjects were scanned in a PET/MRI scanner during natural sleep after median intravenous injection of 14 MBq 15O-water. Regional CBF was quantified using a one-tissue-compartment model employing an image-derived input function (IDIF) from the left ventricle. PET rCBF showed the highest values in the thalami, mesencephalon and brain stem and the lowest in cortex and unmyelinated white matter. The average global CBF was 17.8 ml/100 g/min. The average frontal and occipital unmyelinated white matter CBF was 10.3 ml/100 g/min and average thalamic CBF 31.3 ml/100 g/min. The average white matter/thalamic ratio CBF was 0.36, significantly higher than previous ASL data. The rCBF ASL measurements were all unsuccessful primarily owing to subject movement. In this study, we demonstrated for the first time, a minimally invasive PET/MRI method using low activity 15O-water PET for quantitative rCBF assessment in unsedated healthy newborn infants and found a white/grey matter CBF ratio similar to that of the adult human brain.

Тенденции совершенствования современных ультразвуковых расходомеров

Special measuring instruments — flowmeters — are used to measure the flowrates of various fluids moving in pipelines. In view of a large number of different requirements for flowmeters, various flow measurement methods have been developed and implemented, which are applied depending on the physicochemical properties of the fluid flowing through a pipe, requirements for metrological characteristics, and the simplicity of measuring device design and its maintenance. The ultrasonic measurement method is one of the most promising and intensely developing liquid flowrate measuring methods. It features high reliability and accuracy, ability to measure the flowrate of non-conducting fluids, and the possibility to perform measurements without upsetting the pipeline wall integrity. At the same time, the use of this method involves certain specific features and problems that are inevitably encountered by all developers of ultrasonic flowmeters. The article analyzes the main error components in the measurement results obtained using ultrasonic flow meters (such as the hydrodynamic error, time interval measurement error, error in measuring the difference of propagation times, etc.), examines the methods for improving their accuracy that are used in the modern ultrasonic flow meters, and discusses the ways of their further improvement. The study is primarily focused at reviewing the current state of the art in the development of this method and the possibilities for its further improvement, and providing some information about the major companies producing ultrasonic flowmeters, the instruments manufactured by them, and the applied design and circuit engineering solutions. The article is relevant for the readers who need information about the possibilities of ultrasonic flowmeters and about the prospects of using them, and who are striving to develop a high-precision ultrasonic flowmeter with improved metrological characteristics.

Study on Flow Mapping Method of Ultrasonic Flow Measurement by Robot Remote Control

Study on Flow Mapping Method of Ultrasonic Flow Measurement by Robot Remote Control

F.V. Hunt and my travels with fricative consonants

My training as an electrical engineer aligned well with the way acoustics of speech was modeled, as I learned when working at Bell Laboratories and then in Ken Stevens’ lab at MIT. However, fricative consonants require turbulence noise for their production; studying them for my Ph.D. led me toward aeroacoustics and testing whether circuit models really were adequate for modeling fricatives. The 1984–1985 Hunt and the NATO 1985–1986 postdoctoral fellowships gave me two years in which to learn more. I studied flow measurement methods at MIT’s Mechanical Engineering Department (supervised by Prof. Richard Lyon), then used them in experiments on mechanical models of fricatives and of vocal folds at the Institute of Sound and Vibration Research (ISVR) at the University of Southampton, UK (supervised by Dr. Stephen Elliott and Dr. Phil Nelson). At the Department of Speech Communication and Music Acoustics at KTH, Stockholm, Sweden, supervised by Prof. Gunnar Fant, I analyzed human speech and experimented with v...

Experimental methods for flow and aerosol measurements in human airways and their replicas

Recent developments in the prediction of local aerosol deposition in human lungs are driven by the fast development of computational simulations. Although such simulations provide results in unbeatable resolution, significant differences among distinct methods of calculation emphasize the need for highly precise experimental data in order to specify boundary conditions and for validation purposes. This paper reviews and critically evaluates available methods for the measurement of single and disperse two-phase flows for the study of respiratory airflow and deposition of inhaled particles, performed both in vivo and in replicas of airways. Limitations and possibilities associated with the experimental methods are discussed and aspects of the computational calculations that can be validated are indicated. The review classifies the methods into following categories: 1) point-wise and planar methods for velocimetry in the airways, 2) classic methods for the measurement of the regional distribution of inhaled particles, 3) standard medical imaging methods applicable to the measurement of the regional aerosol distribution and 4) emerging and nonconventional methods. All methods are described, applications in human airways studies are illustrated, and recommendations for the most useful applications of each method are given.

Study on the measurement of paste flow based on the optical fiber system

PurposeFlow measurement plays an important role in modern industrial production. Flow measurement methods based on optical fiber systems have become a main research focus.Design/methodology/approachApplying flow measurement theory and the structural characteristics of optical fiber, flow measurement of paste can be achieved through a combined laser Doppler and optical fiber sensing system based on the principle of optical fiber grating sensors and flow sensors. The system is developed to include light selection, photoelectric detection, a voltage amplifier circuit and a signal filtering circuit.FindingsThe system is shown, through a comparative experiment, to be of higher accuracy than the traditional ultrasonic method.Originality/valueA new method for measuring the paste flow is presented, which is based on the principle of optical fiber Doppler. The method has the advantages of convenient installation, high accuracy and low cost. Experiments show that the method is feasible.

Water flow meter calibration with a master meter method

Master meter method is an efficient way to calibrate flow meters with less time and costs. The master meter method has simpler flow configuration than the gravimetric flow measurement method requires. Maintenance efforts of the master meter method are easier than the gravimetric method. However, the guidelines of master meter method have not been established completely. It is because the notion of relative deviations, which are used as a measure and for comparison calibration, is not clearly understood. On the other hand, the system uncertainty, which is typically used as the calibration and measurement capability of the gravimetric flow standards, are understood very well. In this study, a complete explanation on the master meter method is attempted. First, appropriate calibration conditions are assumed. Second, a suitable calibration procedure is suggested. Third, a mathematical model for the relative deviations is described. Fourth, uncertainty factors of the relative deviations are evaluated. Finally, two examples of the comparison calibration are explained in detail. The master meter method is compatible with the guide to the expression of uncertainty in measurement (GUM, ISO/IEC Guide 98-3:2008). In the examples, it is found that the master meter method can achieve the measurement uncertainty as low as 0.20%.

Mass emissions and carbon trading: a critical review of available reference methods for industrial stack flow measurement

Flow measurements in industrial ducts and stacks are combined with pollutant or greenhouse gas concentrations to deduce mass emissions. These are then used to populate pollutant emission inventories and are traded under emissions trading schemes. Reference methods for flow are described in ISO 10780 and more recently in EN ISO 16911-1. This paper discusses the key differences between the two standards. We consider sources of error in flow measurement and discuss how each standard addresses them. We find that EN ISO 16911-1 introduces a series of improvements that when combined provide critical uncertainty gains that support compliance with the EU’s Emissions Trading System (EU ETS). All these areas are either not addressed or only partially dealt with in ISO 10780. More specifically, EN ISO 16911-1, (a) specifies a wider range of reference techniques enabling the optimal one to be used for different flue gas environments. (b) Provides a method to correct for cyclonic flow effects. (c) Addresses measurement assembly misalignment and specifies tolerance values for it and (d) provides wall effect correction factors. Most importantly, it has been validated through laboratory and field work. However, the quality control specified in EN ISO 16911-1 is more suitable for measurements to support EU ETS requirements and at times can be too onerous for pollutant mass emission reporting that will usually have less stringent uncertainty requirements.

Mass flowrate measurement using the swirl motion in circular conduits

In this paper, a method of mass flow measurement was presented based on swirl motion motivated by specific shapes of swirlers. The measuring principle of the method has been proposed by theoretical analysis and has been verified by experiment and numerical simulation. The relationship between the average axial velocity (vz̅) and the static differential pressure between the pipe wall and pipe center of a cross section downstream of a swirler (∆P) was especially emphasized. It shows that vz̅ is in direct proportion to ∆P when certain fluid flows through a specific swirler. For a certain cross section downstream of a swirler, there exist two places with different radius and different corresponding tangential average velocities, whereas with the same values of tangential average acceleration. The RSM was used as the turbulence model in simulation. Compared with the experiments, the relative errors of the flow coefficient (α) are 1.25% and 4.74% for the cross sections of 2.7D and 11.8D downstream of the swirler, respectively, which are within the scope of acceptable. In addition, we conducted the numerical simulation work of the influences of swirler on α. The results show that the bigger the angle between each slice and pipe cross section and less numbers of slices will achieve less ∆P and bigger α. This method may provide an alternative way to mass flow measurement which is easier to be standardized than other nonstandard differential pressure flowmeters.