Flow Measurement Method Research Articles

Improving Accuracy and Robustness of Space-Time Image Velocimetry (STIV) with Deep Learning

Image-based river flow measurement methods have been attracting attention because of their ease of use and safety. Among the image-based methods, the space-time image velocimetry (STIV) technique is regarded as a powerful tool for measuring the streamwise flow because of its high measurement accuracy and robustness. However, depending on the image shooting environment such as stormy weather or nighttime, the conventional automatic analysis methods may generate incorrect values, which has been a problem in building a real-time measurement system. In this study, we tried to solve this problem by incorporating the deep learning method, which has been successful in the field of image analysis in recent years, into the STIV method. The case studies for the three datasets indicated that deep learning can improve the efficiency of the STIV method and can continuously improve performance by learning additional data. The proposed method is suitable for building a real-time measurement system because it has no tuning parameters that need to be adjusted according to the shooting conditions and the calculation speed is fast enough for real-time measurement.

Methods for Elliptic Flow Measurements with the MPD Experiment at NICA

Methods for Elliptic Flow Measurements with the MPD Experiment at NICA

Fluid velocity monitoring in oil well using fiber laser vibration sensing

A novel method of flow measurement in oil well based on turbulence vibration principle and fiber laser vibration sensor is proposed. The constitutive equations of flow velocity and pipe wall vibration were established, and a kind of optical fiber laser vibration sensor based on hinge structure was designed and installed on the outer wall of oil pipe to measure the fluid flow velocity inside oil pipe. When the fluid flows through the oil pipe, the dynamic pressure will cause the vibration of the pipe wall, resulting in the wavelength change of the fiber laser vibration sensor. The optical fiber interference demodulation technology is used to demodulate the wavelength change to obtain the vibration intensity. The sensitivity of the fiber laser vibration sensor is tested to be 25 pm/g. The field test in oil well showed that the relationship between the vibration intensity of the sensor and the flow rate is quadratic curve, and the minimum flow rate is measured to be 0.041 m/s, which indicates that the system can realize the real-time online measurement of the flow.

Comparison of stereoscopic particle image velocimetry and volumetric particle tracking velocimetry in the wake of a ducted propeller

The interaction of ship and waterway is of utmost importance in inland navigation. Regulations and waterway maintenance rely on assumptions for the damage potential of propeller jets. Scours are to be avoided or repaired at an early stage. As preparation for the validation of future CFD simulations, measurements were carried out in the propeller jet using different methods.2D3C PIV is a non-invasive method for flow measurements in a 2D plane. However, for applications with transient flows, volumetric measurements are desired. Previous Particle Tracking Velocimetry systems suffered from low resolution and difficulties with high seeding density. The system used here attempts to overcome these disadvantages with the Shake-the-Box algorithm and a new hardware design. The focus is on comparing this volumetric flow measurement technique with conventional 2D3C PIV. The test case is the wake flow of a ducted propeller in bollard pull condition.Since the tests were carried out in different facilities, the measured flow fields are not fully comparable. Nevertheless, it is shown that the method is suitable for phase-averaged measurements in addition to the advantages in three-dimensional flows. The findings from this first series of measurements are used for the further development of the system.

Towards flow measurement with passive accelerometers

The aim of this project has been to find suitable methods for flow measurement and characterization with passive accelerometers. The objectives were twofold. Firstly, the process industry could make use of such a sensor for process surveillance. Secondly, the water utilities of today lack simple and cost-efficient alternatives to equip their ageing infrastructures with online flow meters. These kinds of efforts are necessary for the realization of smart maintenance and for the decrease of the currently increasing amount of maintenance needs water utilities of today are experiencing. Liquid flowing in a pipe generates vibrations, detectable with accelerometers fitted along the pipe exterior. The correlated sound from synchronized accelerometers experience a lag which is dependent on the flow rate. Also, if the acquired sound is further processed, there exist a possibility to extract enough features to estimate some additional characteristics, in this case temperature. Experiments were performed at two nominal temperatures, 20 °C and 40 °C. A deep neural network was constructed for non-linear regression purposes to predict flow velocities based on lag and mean frequencies of the vibrations. Further, a proof of concept for this methodology was shown which reached a root mean square deviation from 100.8 L/min to 171.1 L/min for a nominal flow range of 0 to 1500 L/min. In addition, we train a k-nearest neighbour classifier to predict the nominal temperature of our validation dataset with 83 percent accuracy. The work was performed at RISE Research Institutes of Sweden, serving as Sweden’s national metrology institute for liquid flow and acoustics.

Integral absorbance measurement for a non-uniform flow field using wavelength modulation absorption spectroscopy.

Combined with computed tomography (CT), the laser absorption spectroscopy technique is used to measure the two-dimensional distribution information of the flow field. The CT method needs an "integral parameter" as a known quantity. The integrated absorbance satisfies the criterion in the laser absorption spectral measurement. The direct absorption spectroscopy method directly measures the integrated absorbance. However, fitting the absorbance curve is difficult due to the distorted baseline in harsh environments. By contrast, the wavelength modulation spectroscopy (WMS) method has satisfactory noise rejection capability. The difficulty that introduces WMS method to measure the non-uniform flow distribution is the integrated absorbance cannot be written in a mathematical expression. Previous efforts focused on solving the average temperature, concentration, and pressure and recalculating the integrated absorbance. This paper aims to develop an integrated absorbance measurement based on the calibration-free WMS method for non-uniform flow, which is called the calibration-free WMS-A method. First, the relationship between the transmissivity and integrated absorbance was established. Then, integrated absorbance was written into the WMS harmonic signals and solved by comparing the measured and simulated signals. The systematic comparison between the WMS-A and the previous WMS method showed the effectivity of the WMS-A method for non-uniform flow measurement. The reliable integrated absorbance can considerably improve the two-dimensional reconstruction quality.

A multi-level assessment and correction method for Venturi tube flow measurements

The main feed water flow for nuclear power units is measured by Venturi tubes. These use the principle of differential pressure to act as throttling devices. Over the course of their operational life, the passage of medium- and high-speed fluids can erode Venturi tubes, undermining the measurement accuracy of the differential pressure and flow. Venturi tubes play a vital role in nuclear power units, participating in the regulation of the water level in steam generator control systems and protecting reactor signals. Thus, the accuracy of their signal measurements directly affects the safe and stable operation of nuclear power units. This paper analyzes statistical data regarding the main feed water flow measurements from 26 nuclear power units. Combined with the working principles of Venturi tubes, it establishes the mechanism governing erosion in Venturi tubes and its characteristics over long-term operation. A multi-level assessment method for Venturi tube erosion then is proposed that can evaluate the accuracy of flow measurements in terms of degradation, failure and replacement. On the basis of this method, accurate corrections of the differential pressure can be implemented or the tubes replaced. The method was applied in nuclear power units and its effectiveness verified. It can therefore provide a reliable basis for improvements in the safety of nuclear power unit operation and serve as a reference for other chemical and thermal power fields where Venturi tubes are used for measurement and regulation.

An adaptive magnetization structure and method for low field NMR two-phase flow measurement

In low field NMR multiphase flow measurement, the magnetization time and magnetization length are affected by the two-phase flow velocity and water fraction, so it is difficult to realize the complete magnetization of multiphase flow with fixed length magnet. In this paper, an adaptive magnetization structure for two-phase flow is proposed. The pre-magnetization model of the adaptive structure is established based on the magnetization theory of nuclear magnetic resonance. And parameters of the adaptive magnetization structure are determined by analyzing the influence of two-phase flow parameters such as velocity and water fraction on magnetic susceptibility. Finally, the simulation analysis shows that the adaptive magnetization structure can achieve complete magnetization effect for two-phase flow in the range of water fraction 0-36% and flow rate 0-4.66m/s, which provides the necessary conditions for the accurate measurement of NMR two-phase flow and provides a new idea for the design of NMR two-phase flow measurement sensor.

Simulation of Lake Water Volume in Ungauged Terminal Lake Basin Based on Multi-Source Remote Sensing

Obtaining the water volume of small- and medium-sized lakes in enclosed watersheds with scarce data is a global focus of research. River flow into a lake is an important factor affecting the water volume. However, most river flow measurement methods involve long cycles, low efficiency, and transdisciplinary expertise, making rapid assessments in ungauged basins impossible. This paper proposes a remote sensing flow estimation method based on multi-source remote sensing data, which quickly assesses river flow and provides important input data for lake water volume simulation. The cross-section flow was estimated by extracting the river width. The calculated results were consistent with the measured data, with accuracy greater than 90%. The results compared with daily data measured at hydrological stations, and the Nash coefficient was greater than 0.9. Additionally, the simulation method for lake area, water volume, and water level was constructed using river inflow input data, greatly reducing the parameters required by the conventional lake water volume simulation method. Based on the remote sensing discharge estimation method, we quickly and conveniently obtained changes in river flow into the lake, simulated lake water volume, and provided the basis for water resource management in terminal lake basins with scarce data.

Precise electroosmotic flow measurements on paper substrates

A novel method for electroosmotic flow (EOF) measurement on paper substrates is presented; it is based on dynamic mass measurements by simply using an analytical balance. This technique provides a more reliable alternative to other EOF measurement methods on porous media. The proposed method is used to increase the amount and quality of the available information about physical parameters that characterize fluid flow on microfluidic paper-based analytical devices (μPADs). Measurements were performed on some of the most frequently used materials for μPADs, i.e., Whatman #1 , S&S, and Muntktell 00A filter paper. Obtained experimental results are consistent with the few previously reported data, either experimental or numerical, characterizing EOF in paper substrates. Moreover, a thorough analysis is presented for the quantification of the different effects that affect the measurements such as Joule effect and evaporation. Experimental results enabled, for the first time, to establish well-defined electroosmotic characteristics for the three substrates in terms of the magnitude of EOF as funtion of pH, enabling researchers to make a rational choice of the substrate depending on the electrophoretic technique to be implemented. The measurement method can be described as robust, reliable, and affordable enough for being adopted by researchers and companies devoted to electrophoretic μPADs and relatedtechnologies.

Experimental Research on the Efficiency of Impulse Turbine Based on Ultrasonic Flow Measurement Method

In this paper, we studied the impulse turbine of a power station based on the ultrasonic flow measurement method. Efficiency tests were carried out on the nozzle head, nozzle needle and deflector disc spring of the unit before and after the transformation. The results showed that the absolute efficiency of the unit before and after the transformation was basically the same. The efficiency value and economic performance have been improved to a certain extent, and the results obtained by using the ultrasonic method to carry out the unit efficiency test are correct and credible.

Invariant method for measuring wet gas flow rate

The article deals with one of the important tasks of modern flow measurement, which is related to the measurement of the flow rate and the amount of wet gas. This task becomes especially important when it becomes necessary to obtain information about the separate amount of the dry part of the gas that is contained in the form of a mixture in the wet gas stream. The paper presents the principle of operation and structure of the invariant system for measuring the flow rate of wet gas, which is based on the combined use of differential pressure flowmeters and Coriolis flowmeters. The operation of the invariant wet gas flow rate measurement system is based on the simultaneous application of the multichannel principle and the partial flow measurement method. Coriolis flowmeters and the differential pressure flowmeter are used as the main elements of the system. The proposed measurement system does not offer applications for gases with abundant drip humidity. The article provides information about the test results of the proposed invariant system. The estimation of the metrological characteristics of the invariant system when measuring the flow rate of wet gas is given. The obtained test results of the invariant wet gas flow rate measurement system are relevant for natural gas production, transportation, and storage facilities.

Feasibility of using thermal response methods for nonintrusive compressed air flow measurement

Robust, low-cost nonintrusive flow meters are of interest in many industries. In particular, a reliable nonintrusive flow measurement for the diagnosis of air leaks in compressed air systems is desirable. Measurement of the air flow due to leaks in the system ensures an accurate estimation of potential cost and energy savings. This study evaluates a novel method of using thermal responses to nonintrusively measure leakage rates in compressed air lines. The method uses heat and the resulting thermal response to calculate the flow rate inside the compressed air line. Compared to the current methods for flow measurement, this method can simplify flow measurement while decreasing the sensitivity to errors when measuring flow rates. In this study, the methodology of the proposed method is explained along with the potential advantages to the design. Two approaches are evaluated: a dynamic step response and sinusoidal frequency response. Simulated tests evaluate the feasibility of the proposed methods, followed by experiments that validate the simulation results. A clear correlation between the thermal step response and the flow rate indicate viability of the proposed method in simulation. Experimental results yielded similar results, confirming the validity of the proposed method. The results of a field test in an industrial environment demonstrate the capability of the approach to other flow rate measurement techniques.

Methods for anisotropic flow measurements with the MPD Experiment at NICA

The anisotropic collective flow is one of the important observable values sensitive to transport properties of strongly interacting matter created in relativistic heavy-ion collisions. The performance of Multi-Purpose Detector (MPD) at NICA collider for elliptic flow measurements with Monte-Carlo simulations using collisions of Au+Au and Bi+Bi ions employing several state of the art event generators is studied. Different methods for flow measurements as event plane and direct cumulants are used to investigate the contribution of non-flow correlations and flow fluctuations.

Determination of zero-flow for the thermal dissipation method of sap flow measurements in Mediterranean climates

Determination of zero-flow for the thermal dissipation method of sap flow measurements in Mediterranean climates

Multimodal Two-Phase Flow Measurement Using Dual Plane ECT and GRT

This work assesses the accuracy of two-phase flow measurement, based on cross correlation (XC) and cross-spectrum (CS) velocity computation, using dual plane nonintrusive electrical capacitance tomography (ECT), over a broad spectrum of horizontal flow configurations, combined with fraction distribution measurements from gamma-ray tomography (GRT). The measurement of two-phase flow encompasses the measurement of both the velocity and the phase concentration of the flow components. The accuracy of the flow velocity is still an open discussion and remains a key challenge in the field of multiphase flow measurement. The velocities of the two-phase components vary, both in between them and across the pipe cross section. This study assesses the use of XC techniques as methods for calculating the cross-sectional velocity distribution by deriving the transit time of the fluid flowing through two parallel ECT sensor arrays mounted on the perimeter of a pipe. The spectral distribution of the velocities is assessed for improved accuracy of individual component velocities. A dual-plane ECT is adopted for the velocity measurements and is combined with state-of-the-art density-based cross-sectional phase fraction distribution from a GRT system to measure the volumetric flow rates of the two phases. The results show that the CS method provides enhanced velocity estimation for both flow phases over the conventional XC technique. Further improvement was reported using a simple predictive correction model resulting in flowrate estimation accuracy of ±10%. The method for two-phase flow measurement suggested in this work leverages the accuracy of the tomography systems on accurate fraction measurement and fast data acquisition to lead to potential enhancement in process control by enabling a more accurate prediction of components velocities.

Underwater low-velocity gas flow measurement based on passive acoustics with stable volume resolution

Underwater gas escape is widespread in the marine and industrial fields and the low-velocity gas caused by trace gas escape is difficult to be detected or measured. An underwater low-velocity gas flow measurement method based on passive acoustics with stable volume resolution is proposed in this paper. The elastic wave signal generated by the underwater gas is acquired by a hydrophone and filtered by the wavelet packet filtering method. The flow rate can be cumulatively estimated by the relationship between the bubble and the spectrum characteristics. The volume resolution of the bubble is stable, which is achieved by adjusting the signal frequency resolution. This method is adaptive to the processing of bubbles in different volumes. The stable volume resolution is helpful to reduce the random error for the cumulative continuous bubble volume estimation. Underwater gas leakage experimental platforms were established under laboratory conditions and lake conditions. The results show that the method has high accuracy and stability. For a single bubble and low-velocity flow conditions under laboratory conditions, the minimum error is 0.3% and the maximum error is 3.9% between 5 and 25 ml min−1. For the low-velocity flow under lake conditions, the minimum error is 0.8% and the maximum error is 8% between 10 and 60 ml min−1.

Adaptive filtering based sodium flow measurement method for in-situ calibration

Permanent magnet sodium flowmeter is used to measure the coolant-sodium flow to ensure the safe operation of the fast reactor. Due to the requirements of the actual working environment, it had to be calibrated in situ. An adaptive filtering method is applied to the calculation of the output signal delay time of the permanent magnet sodium flowmeter with embedded vortex generator. According to the mean square error minimization principle of output signal and expected signal, the feedback structure of the algorithm is designed. The error of output signal and expected signal is used as feedback information, and filter parameters are automatically adjusted in the iteration process, so that the first signal continuously approximates the second signal after passing through the filter, and finally the value of the abscissa corresponding to the maximum peak of filter function reflects the delay time between the two signals. It achieves the 0.5-level measurement accuracy.

Flow measurement method of complex flow in heat exchange casing

Fluid plays an important role in engineering application and the accurate control of the carrier is the premise of energy efficient conversion and management, such as the primary air volume of the boiler, the reactor inlet flowrate, the amount of oil and air intake of internal combustion engine, etc. Therefore, flowmeter plays an important role in energy conversion and management. In this work, a high-low frequency combined with reflection-penetration synchronization flowmeter was designed to measure the flowrate in casing device based on the characteristics of different frequencies of sound. The flowrate calculation method of casing device is given and verified by numerical simulation. The results show that the flowrate of different flow states can be calculated accurately by using the high-low frequency combined with reflection-penetration synchronization method. At the same time, the method can also be used in electromagnetic wave, optical and other fields.

A large Flow Signal Processing and Measurement Method based on Ultrasonic Gas Meter

Ultrasonic flowmeter is extensively used in petrochemical, metallurgical and other industries for its non-contact measurement, large measuring range, stable measurement results and no pressure loss. The time difference measurement method is adopted by the ultrasonic gas meter that can reduce the error caused by the variation of sound velocity with the temperature of the fluid. But there are some problems in the large flow point and small flow point in the time difference measurement method, such as low precision, low repeatability, poor stability. According to study the influence of flow velocity on ultrasonic echo signals, a method of variable threshold and variable gain based on peak detection is proposed and the prototype of gas ultrasonic flowmeter is designed in this paper. The national standard device, 100L automatic bell cover test device, is applied to verify the design scheme proposed in this paper. The experimental results indicates that the validity of variable threshold and variable gain ultrasonic signal processing method based on peak sampling is verified, in addition, the measurement accuracy and repeatability of the ultrasonic gas meter are enhanced at the point of large flow (large flow rate).