Flow Measurement Method Research Articles

Invariant system for measuring the flow rate of wet gas on Coriolis flowmeters

One of the important tasks of modern flow measurement is to measure the flow rate and the amount of wet gas. This task becomes especially important when there is a need to obtain information about the amount of dry gas at the production facilities. The paper presents the principle of operation and structure of the invariant wet gas measurement system. The work of the invariant flow measurement system is based on the application of the principle of multichanneling and the method of partial flow measurement. Coriolis flowmeters are used as the main elements of the system. The proposed measurement system does not imply the use for gases with abundant droplet moisture. The authors propose a method of verification of the measurement system, which is currently limited by the measurement error of moisture in the gas equal to 5%. The article also provides information on the results of the test of the system.

An improved single probe method for sap flow measurements using finite heating duration

Because of its low cost and simple fabrication, it is easy to advocate for the single probe method as a method of choice in sap flow studies. An improved single probe method with finite heating duration (F-SPHP) is verified both in cut stem segments and in the field using mature beech (Fagus sylvatica L.) trees. The F-SPHP method is based on an analytical solution of the partial differential equation for combined heat conduction and convection, which shows large relative sensitivity to thermal conductivity (K). The F-SPHP method is able to measure sap flux densities (SFD) between 2 and 36 cm3 cm−2 h−1 (heat pulse velocity (Vh): 3–60 cm h−1) in the cut stem segment experiment. This is an improvement compared to the instantaneous single probe heat pulse (I-SPHP) method which cannot accurately measure low (Vh < 20 cm h−1) sap flow. Sapflow+ (a four-needle heat pulse method) is used for field validation, and when compared with gravimetric measurements, slopes of 0.853 and 0.730 are obtained for F-SPHP and Sapflow+, respectively. Patterns measured with F-SPHP and Sapflow+ in mature beech trees in the forest are similar at all measurement positions and temperature correction is needed for both methods when natural temperature gradients are steep. Compared with multi-probe methods, the single probe method with finite heating duration has the advantage of causing less damage to conductive tissue.

Skin blood flow measurements during heat stress: technical and analytical considerations.

During heat stress, the skin vasculature can greatly increase conductance secondary to vasodilation. The subsequent increase in skin blood flow allows for convective heat transfer from the core to the skin and between the skin surface and the surrounding environment. Measurement of skin blood flow, therefore, provides valuable information regarding heat exchange between the body and the environment. In addition, assessment of skin blood flow can be used to study vascular control mechanisms. Most often, skin blood flow is measured by venous occlusion plethysmography, Doppler ultrasound, laser-Doppler flowmetry, and, more recently, optical coherence tomography. However, important delimitations to each of these methods, which may be dependent on the research question, must be considered when responses from these approaches are interpreted. In this brief review, we discuss these methods of skin blood flow measurement and highlight potential sources of error and limitations. We also provide recommendations to guide the interpretation of skin blood flow data.

소듐 유량 측정을 위한 분절형 웻지 유량계 설계 평가

In order to measure the flow rate of liquid sodium, the flow measurement method should be determined by considering the opacity of sodium, the chemical reaction with air and water, and so on. By using the segmental wedge flowmeter which is one of the representative devices for flow measurement, the methodology for measuring the liquid sodium flow was examined and the flow characteristics were observed. The variations of the discharge coefficients according to various flow conditions were also evaluated. In addition, the structural integrity at high temperature condition was evaluated by using the liquid sodium as a working fluid and these study results were reflected in the design of the segmental wedge flowmeter.

Study on flow measurement method of vertical axial flow pump based on the relationship between flow and differential pressure of two points in elbow inlet passage

Under the support of computational fluid dynamics (CFD), a new flow measurement method for vertical axial flow pump with elbow inlet passage was put forward. In order to select suitable turbulence model to predict wall pressure in elbow inlet passage, Standard k-ε, RNG k-ε and Realizable k-ε models were used to simulate the flow field. In comparison with experimental results, the conclusion could be drawn that it is feasible to predict the wall pressure of elbow inlet passage with Realizable k-ε turbulence model. For model pump, based on the data from the model test and the numerical simulation respectively, the equations about discharge of pump and two-point differential pressure were obtained with the least square method and the results indicated that coefficients of the equations were slightly different. Based on the same numerical simulation method as model pump, the differential pressures were obtained by cloud computing with large parallel for prototype pump. In order to improve the prediction accuracy of discharge of prototype pump, a new corrected method was proposed on the condition that the relative errors about two-point differential pressures between numerical simulation and experiment for model pump were the same as those for prototype pump according to Euler similarity criterion. It is concluded that the method improves the accuracy and simplicity of flow measurement for vertical axial flow pump with elbow inlet passage and the approach to predict the flow of pump is feasible.

Development of laser speckle blood flowmeter for evaluating the physiological function of skin

Objective: We developed and demonstrated laser speckle flowgraphy (LSFG) for two-dimensional (2D) skin blood flow (SBF) measurements to facilitate the noninvasive comparisons of SBF between individuals. Approach: By using morphing technology with a face mesh to compare SBF spatial distributions among individuals, we examined the practicability of SBF measurement with LSFG. Main results: (1) The uniformity of SBF measurement was demonstrated by examinations at different distances and angles for healthy subjects. (2) Mean blur rate (MBR)—a blood flow index of LSFG—exhibited significant correlation with the thermal diffusion method (TDM)—an established blood flow measurement method—suggesting that MBR is an effective index of SBF. (3) Blowout time, the half-width duration/duration of one cardiac cycle, exhibited significant negative correlation with age and positive correlation with stratum corneum hydration. Significance: These results suggest that LSFG is useful for evaluating SBF-related skin properties, and it has significant potential in medicine and cosmetology.

A robust calibration method for seven-hole pressure probes

Multi-hole pressure probe remains an incomparably efficient method of flow measurement due to its simplicity and convenience. An appropriate calibration method is necessary to establish the relations between flow parameters and pressure data. In this paper, a robust calibration method for seven-hole pressure probes is presented, which can also be applied when a hole port is malfunctioning. First, a seven-hole probe was designed and manufactured by 3D printing techniques, and calibration measurements were conducted with a two-degree of freedom calibration apparatus in wind tunnel. Second, theoretical expressions for static pressure coefficients of seven-hole probes were deduced, which guides the establishment of new pressure normalization method in the absence of static and total pressure. Thereafter, a calibration algorithm using the new pressure normalization method was proposed. Finally, effects of sample selection criteria, sample size, and atmospheric static pressure offset on the calibration accuracy of the new algorithm were evaluated. And the case that one port is invalid was studied. Based on the findings obtained from this study, the feasibility and robustness of the new calibration method were validated, and the method can also be easily applied to other multi-hole (including but not limited to seven-hole) pressure probes.

Two-dimensional velocity distribution modeling for natural river based on UHF radar surface current

Non-contact flow measurement method plays an increasingly important role in river discharge measurement. However, most channel cross-section velocity distribution models proposed by researchers have certain limitations in application, underwater velocities are always necessary when applied in narrow channels, which makes it challenging to calculate natural river discharge using water-surface velocities measured by remote sensing instruments. This letter takes water-surface velocities detected by UHF radar as boundary conditions and a new velocity distribution model is derived based on the Reynolds-Averaged Navier-Stokes (RANS) equations. UHF radar measures surface velocities of the cross-section, and velocities on the river bed of the cross-section are considered to be 0. The RANS equations are simplified to be a two-dimensional Poisson equation and the cross-section velocity distribution is solved by using the closed boundary conditions. Some field experiments were conducted in the Hanjiang River at Xiantao, Hubei, China in September 2017 and April–July 2018, the processing results of which show that the proposed model is superior to the power law and the log law models, especially near the side wall (narrow channel region). River discharges calculated by this method are highly consistent with those provided by Hubei Xiantao hydrologic station, which verifies the reliability of the model and the feasibility of using UHF radar to measure natural river discharge continuously and automatically.

Sensitivity of the Winter-Kennedy method to different guide vane openings on an axial machine

This work studies the effects of guide vane openings (GVOs) on the Winter-Kennedy (WK) flow measurement method using CFD. The dependence of the WK coefficient with GVOs and its physical mechanism are presented. Although the WK method is reported to be sensitive to different factors including GVO, it is still unclear to which extent the GVO can be changed without modifying the WK coefficient significantly and the mechanism leading to such modification, if any. A numerical model of a Kaplan model turbine with a semi-spiral casing is developed and used to such purpose. Previously conducted experiments on the model turbine are used to validate the numerical results. The magnitude and behavior of the secondary flow are investigated together with the WK coefficients. The GVO is found to have an impact on the WK method, and the impact increases with the GVOs as the flow structure change. A suitable location to minimize the impact of the GVO is suggested. Furthermore, the theoretical WK constant with a suitable location and configuration are also presented; this can be useful in the absence of the measured WK coefficient.

A gas flow meter with linear sensitivity based on freely-suspended nanofilms of smectic liquid crystal

A technique of mechanical airflow sensing based on coupling to a film of fluid smectic liquid crystals is presented. A gas jet confined to a narrow channel induces flow in a continuous, freely suspended film with racetrack geometry, whose velocity field is then mapped using video microscopy and particle tracking techniques. Because the nanofilm has so little mass compared to the air, its velocity provides a direct readout of the velocity profile of the gas in the channel. This method of flow measurement offers several advantages over conventional mechanical flow meters: It has linear sensitivity, and so, it can operate at low flows, and the energy lost due to the measurement is negligible.

Diagnostic methods for measurement of peripheral blood flow during exercise in patients with type 2 diabetes and peripheral artery disease: a systematic review.

Measurement of systolic ankle and to some extent toe pressure in patients suffering from combined type 2 diabetes mellitus (T2DM) and peripheral arterial disease (PAD) face several obstacles due to complex changes in the vascular bed. The aim of this review was to address the current literature on blood flow during exercise in patients with PAD and T2DM and assess the feasibility of these methods to diagnose and grade arterial insufficiency. A systematic review of the PubMed and EMBASE databases, supplemented by hand searching was performed according to PRISMA guidelines. Clinical studies evaluating methods to investigate peripheral blood flow in patients with PAD and T2DM during exercise were included. In total nine eligible studies consisting of 1105 non-diabetic PAD patients, 336 diabetic PAD patients, 161 diabetic patients without PAD and 69 healthy controls were included in the review. Near-infrared spectroscopy (NIRS) was described in three studies, transcutaneous oxygen pressure measurement (TcpO2) in two and the following methods described in single studies: thermodilution, contrast enhanced ultrasound (CEUS), scintigraphy and TcpO2 in combination with ultrasound. These studies shows that patients with PAD and T2DM compared with patients with only PAD suffers different atherosclerotic lesions characterised by increased arterial stiffness and microcirculation abnormalities, not well differentiated by pressure measurement alone. Investigating patients with PAD and T2DM during exercise reveals that NIRS, TcpO2, CEUS, and scintigraphy have distinct advantages over ankle and toe-pressure. Using methods like NIRS, TcpO2, CEUS and scintigraphy, peripheral blood flow during exercise can be measured at a detailed level and potentially improve future severity grading in patients with combined T2DM and PAD.

Heterogeneity and Variability in Pressure Autoregulation of Organ Blood Flow: Lessons Learned Over 100+ Years.

Pressure autoregulation is an organ's intrinsic ability to maintain blood flow despite changes in perfusion pressure. The purpose of this review is to discuss autoregulation's heterogeneity among different organs and variability under different conditions, a very clinically relevant topic. Systematic search of Ovid MEDLINE; nonsystematic search of PubMed, Google Scholar, and reference lists. Animal or human studies investigating the potency or variation of pressure autoregulation of any organs or the association between autoregulation and outcomes. Two authors screened the identified studies independently then collectively agreed upon articles to be used as the basis for this review. Study details, including subjects, organ investigated, methods of blood pressure intervention and blood flow measurement, and values of the lower limit, upper limit, and plateau were examined. Comparative canine studies were used to demonstrate the heterogeneity of pressure autoregulation among different organs and validate the proposed scale for organ categorization by autoregulatory capacity. Autoregulatory variability is discussed per organ. The association between cerebral autoregulation and outcome is summarized. The organs with robust autoregulation are the brain, spinal cord, heart, and kidney. Skeletal muscle has moderate autoregulation. Nearly all splanchnic organs including the stomach, small intestine, colon, liver, and pancreas possess weak autoregulation. Autoregulation can be readily affected by a variety of clinically relevant factors. Organs with weak or weakened autoregulation are at a greater risk of suboptimal perfusion when blood pressure fluctuates. Cerebral autoregulation and outcomes are closely related. These lessons learned over 100+ years are instructive in clinical care.

Flowmeter based on a piezoelectric PVDF tube

The present work aims at demonstrating the applicability of using tubes made of the polymer PVDF as intrinsic flowmeters, considering the peculiar piezoelectric properties of the PVDF-β polymorph and using as flow measurement method the Flow-Induced Vibration (FIV) technique. The work methodology consisted of initially characterizing the material of a commercial PVDF tube spectroscopically, using the Fourier Transform Infrared Spectroscopy (FTIR) technique, to confirm the presence of PVDF-β. Then, the PVDF tube was installed in a hydraulic test circuit and electromechanically tested, to identify the levels of electrical voltages generated by the vibration caused by the passage of water through the tube. To compare the vibration signals, simultaneous measurements were made with commercial accelerometers and with a commercial PVDF film built specifically as a piezoelectric transducer. The results of the FIV tests allowed confirming that the standard deviation of the voltage signal measured by the PVDF tube is related to the flow rate. The uncertainties associated with flow rate measurement by the tube showed a considerable reduction in the higher flow rates. On the other hand, in the lowest flow rate levels, a high instability was observed, possibly due to the process of initial mechanical accommodation of the tube. Despite this, a strong relationship between the signal generated by the PVDF tube and the flow rate that induced this vibration has proven the potential applicability of the PVDF tube as a water flowmeter.

High pressure measurement of mud density and flow rate for oil and gas well construction: Making the case for X-Ray metering

Abstract With a myriad of flow and density sensors available, it can be difficult to decide on the right metering technology to make density and mass flow rate measurements, that suits both application and cost requirements. Operational specifications listed in product brochures typically apply to tests done under highly controlled conditions and generally fail to account for the extreme variability in flow conditions of drilling and completions fluids in the real world. Thus, time and other resources can be wasted by the end users in trying to validate the various meters. Even when right metering technology is selected the measured values often have low accuracy and low measurement frequency. The intent of this paper is to provide a high level overview of the working principles of some of the mainstream metering technologies, identify applications they are well suited for, clarify their limitations, and provide an overview into current research to address these limitations. The paper will allow the reader to narrow down options for appropriate density and flow metering solutions for particular applications, and at the same time highlight the gaps and needs that need to be addressed by further research and development. The paper also discusses an X-ray based metering technology that overcomes some of the disadvantages and deficiencies of established meters. Recent work on characterizing the drilling fluid density and flow rate at the high pressure well inlet using X-rays has shown that these measurements can now be made with greater than 99% accuracy and at 1 Hz measurement frequency. Such level of accuracy and measurement frequency is not offered by any of the mainstream metering technologies. It is expected that the X-ray based technology when implemented will lead to a step-change improvement in current density and delta flow (flow in – flow out) assessment, and will thereby positively contribute to improved hydraulics management, better and earlier kick detection, and further enhanced managed pressure drilling control. In this paper we build upon the existing work on X-ray based density and flow rate measurements of drilling fluids. Specifically, we discuss preliminary work towards development of a new flow measurement technique which can measure flow rate using an X-ray flat panel detector. Using a flat panel detector offers a cheaper alternative to the existing high speed imaging based flow measurement methods. We also share results from a method developed for real-time calibration of the X-ray detectors. Using the calibration method X-ray measurements are shown to have a repeatability of greater than 99%. A section is also dedicated to characterizing the intensity output from the X-ray source. Finally, we show that X-ray density measurements conducted with static fluids in existing literature remain unaffected when the same density fluid flows through a pipe.

Calibration of Midstream Buoy Coefficient Based on Flow Measurement

The midstream float method is a standby flow measurement method adopted by hydrological stations when the river floods are rising and falling sharply and the flow meter is difficult to measure or special water regime occurs. In this paper, based on the Years of measured flow data of Xiaolongtan Hydrological Station of Nanpanjiang River, the Midstream Buoy Coefficient in the natural river course of Nanpanjiang River Basin is calculated and analyzed. The average buoy coefficient is calculated by measuring the actual flow divided by the imaginary flow and the average value is 0.76 and the maximum variation is less than 14%. This method can solve the actual needs of high flow measurement. The results can provide technical basis for sudden flood, special water regime, emergency monitoring, flood prevention and early warning. The flow measurement under the condition of insufficient testing personnel.

The Past and Present of Discharge Capacity Modeling for Spillways—A Swedish Perspective

Most of the hydropower dams in Sweden were built before 1980. The present dam-safety guidelines have resulted in higher design floods than their spillway discharge capacity and the need for structural upgrades. This has led to renewed laboratory model tests. For some dams, even computational fluid dynamics (CFD) simulations are performed. This provides the possibility to compare the spillway discharge data between the model tests performed a few decades apart. The paper presents the hydropower development, the needs for the ongoing dam rehabilitations and the history of physical hydraulic modeling in Sweden. More than 20 spillways, both surface and bottom types, are analyzed to evaluate their discharge modeling accuracy. The past and present model tests are compared with each other and with the CFD results if available. Discrepancies do exist in the discharges between the model tests made a few decades apart. The differences fall within the range −8.3%–+11.2%. The reasons for the discrepancies are sought from several aspects. The primary source of the errors is seemingly the model construction quality and flow measurement method. The machine milling technique and 3D printing reduce the source of construction errors and improve the model quality. Results of the CFD simulations differ, at the maximum, by 3.8% from the physical tests. They are conducted without knowledge of the physical model results in advance. Following the best practice guidelines, CFD should generate results of decent accuracy for discharge prediction.

A New Algorithm for Blood Flow Measurement Based on the Doppler Flow Spectrogram

The blood flow is traditionally obtained by multiplying the cross sectional area of the blood vessel and the average blood speed in the cross section, or is given by the integral of the product of the cross section and blood velocity of each element. However, both methods are affected greatly by the measurement precision of the area and velocity. A new algorithm, which is based on the Doppler blood flow spectrogram, is proposed to measure the blood flow in this paper. In the algorithm, the blood flow is calculated according to the double integral of a Doppler blood flow spectrogram. To verify the feasibility of the proposed algorithm, experiments have been performed on the Doppler blood-mimicking system $KS205D-1$ using the SonixTouch ultrasonic system. In addition, linear-regression analysis is carried out to observe the correlation factors between the experimental values and real values of different flow rates. Experimental results show that the calculated values and real values correlate significantly $(r>0.969, P . Experimental results both on males and females also verified the proposed algorithm $(r>0.915, P . Hence the proposed algorithm is proven effective for relative mean blood flow measurement. Due to the special structure of the human brain, it is difficult to measure the cross sectional area of blood vessel with ultrasound imaging. In this algorithm, there is no need to measure the cross sectional area of the blood vessel. Therefore, the proposed algorithm has the potential to be a new method for clinical ultrasonic blood flow measurement, especially cerebral blood flow measurement.

Quantification of blood flow in the fetus with cardiovascular magnetic resonance imaging using Doppler ultrasound gating: validation against metric optimized gating

IntroductionFetal cardiovascular magnetic resonance (CMR) imaging is used clinically and for research, but has been previously limited due to lack of direct gating methods. A CMR-compatible Doppler ultrasound (DUS) gating device has resolved this. However, the DUS-gating method is not validated against the current reference method for fetal phase-contrast blood flow measurements, metric optimized gating (MOG). Further, we investigated how different methods for vessel delineation affect flow volumes and observer variability in fetal flow acquisitions.AimsTo 1) validate DUS gating versus MOG for quantifying fetal blood flow; 2) assess repeatability of DUS gating; 3) assess impact of region of interest (ROI) size on flow volume; and 4) compare time-resolved and static delineations for flow volume and observer variability.MethodsPhase-contrast CMR was acquired in the fetal descending aorta (DAo) and umbilical vein by DUS gating and MOG in 22 women with singleton pregnancy in gestational week 360 (265–400) with repeated scans in six fetuses. Impact of ROI size on measured flow was assessed for ROI:s 50–150% of the vessel diameter. Four observers from two centers provided time-resolved and static delineations. Bland-Altman analysis was used to determine agreement between both observers and methods.ResultsDAo flow was 726 (348–1130) ml/min and umbilical vein flow 366 (150–782) ml/min by DUS gating. Bias±SD for DUS-gating versus MOG were − 45 ± 122 ml/min (−6 ± 15%) for DAo and 19 ± 136 ml/min (2 ± 24%) for umbilical vein flow. Repeated flow measurements in the same fetus showed similar volumes (median CoV = 11% (DAo) and 23% (umbilical vein)). Region of interest 50–150% of vessel diameter yielded flow 35–120%. Bias±SD for time-resolved versus static DUS-gated flow was 33 ± 39 ml/min (4 ± 6%) for DAo and 11 ± 84 ml/min (2 ± 15%) for umbilical vein flow.ConclusionsQuantification of blood flow in the fetal DAo and umbilical vein using DUS-gated phase-contrast CMR is feasible and agrees with the current reference method. Repeatability was generally high for CMR fetal blood flow assessment. An ROI similar to the vessel area or slightly larger is recommended. A static ROI is sufficient for fetal flow quantification using currently available CMR sequences.

Design and implementation of a low-cost device for measuring sap flow in woody species

Transpiration is a key variable in water balance. Sap flow measurement methods allow to estimate transpiration at plant level, but scalable at the stand, river basin or ecosystem level. This requires recording data continuously, for which there are commercial devices, but they are specialized and expensive. This document shows that it is possible to integrate a data capture, management and storage system, as a counterpart to a commercial system such as Campbell's CR-100, for measuring and recording environmental variables, with a notable reduction in costs. The methodology used to develop a device for the estimation of sap flow using the heat ratio method, the design of the Arduino-based electronic circuit and the software, with register 13-64-171 of the Dirección Nacional de Derechos de Autor, is presented.

Non‐invasive three‐dimensional power Doppler imaging for the assessment of acute cerebral blood flow alteration in a mouse model of subarachnoid haemorrhage

We aimed to evaluate the feasibility of a non-invasive method of cerebral blood flow (CBF) measurement using high-frequency power Doppler ultrasound imaging in a mouse model of subarachnoid haemorrhage (SAH). The 3-dimensionally (3D) reconstructed blood flow signals (%vascularity) within the brain volume of the middle cerebral artery territory correlated well with reference parameters, baseline carotid artery blood flow (r2 =0.52, P<0.0001) and normalized CBF changes (r2 =0.74 P<0.0001). These data suggest that the 3D power Doppler analysis may have the potential for reflecting real-time CBF changes during the acute phase of experimental SAH, which may be applicable to preclinical studies on early brain injury.