Flow Velocity Measurement Method Research Articles

Experimental Validation of the Remote Sensing Method for River Velocity Measurement Using an Open-Source PIV Scheme—Case Study: Antisana River in the Ecuadorian Andes

This study presents the experimental validation of a remote sensing method for river flow velocity measurement, from which discharge is calculated, using Particle Image Velocimetry (PIV) combined with Unmanned Aerial Vehicles (UAVs). The case study focuses on the Antisana River in the Ecuadorian Andes, a region with challenging geography where accurate flow measurement is crucial for hydroelectric projects. The validation results demonstrate that the velocity measurements obtained through PIV closely align with those from standardized traditional methods. Furthermore, integrating technologies such as LiDAR for cross-sectional measurements, along with UAVs, would enable the accurate estimation of discharge in difficult-to-access areas. This approach has the potential to significantly enhance hydrological studies and water resource management in remote regions, especially for hydroelectric projects in the Ecuadorian Andes.

A model for multiphase flow velocity calculation in pipelines based on ultrasonic sensors

In the petroleum and natural gas industry, a wide variety of multiphase fluids are prevalent, and precise measurement of their flow velocity in pipelines holds significant importance for different stages of well drilling and construction. However, due to the presence of large solid particles and the corrosive nature of the liquid phase in multiphase fluids within the petroleum industry, invasive measurement methods struggle to maintain long-term acceptable detection accuracy. Therefore, the non-contact fluid flow velocity measurement method based on ultrasonic sensors exhibits substantial research value. Nonetheless, when employing this approach for pipeline multiphase fluid flow velocity measurement, the abundance of background interference noise at the site poses challenges in Doppler echo signal reconstruction and results in lower precision for frequency shift extraction, leading to considerable errors in flow velocity calculation results. To address this issue, the present study utilizes a transmit-receive separated continuous wave ultrasonic sensor. First, a mathematical model is developed for the superimposed signal of ultrasonic Doppler echoes within the pipeline. Next, a novel signal reconstruction method is proposed by employing Chebyshev polynomials for interpolation computation of the sampled discrete signals. Subsequently, a Doppler shift model is introduced, leading to the formulation of a new model for multiphase flow velocity calculation in pipelines based on ultrasonic sensors. Finally, a comparison experiment for full-pipe multiphase flow velocity detection is conducted to validate the computational performance of the new model. The experimental results show that, compared with the FFT model and the conventional cross correlation model, the comprehensive meter factor of the ultrasonic flow measurement system with the new model is reduced by 0.024 445, the accuracy is reduced by 2.98%, the nonlinear error is reduced by 2.4405%, the average relative error is reduced by 0.646%, the standard deviation is reduced by 0.045 175, and the root mean squared error is reduced by 0.029 615.

Fundamental Study on the Development of an Inexpensive Velocity Meter for River Floods Using Stagnation Points

In recent years, climate change has occurred on a global scale, causing frequent flooding in many regions. In response to this situation, watershed-wide flood management is attracting attention around the world as a promising approach. Under these situations, Japan has also made a policy shift to watershed-based flood management, which aims to manage floods and control runoff in the entire watershed. For this management, it is essential to obtain areal hydraulic information, especially flow information, from each location in the watershed. To measure river flow, it is necessary to measure water level and velocity. While it is becoming possible to make area-based observations of water levels using simple methods, various attempts have been made to measure the velocity, but continuous data cannot be obtained using simple methods. Low-cost flow velocity meters would facilitate the simultaneous and continuous accumulation of data at multiple points and enable the acquisition of areal flow information for watersheds, which is important for watershed-based flood management. This study aims to develop an inexpensive, simple velocity meter that can be used to make areal measurements within watersheds, and to make this velocity meter usable by residents, thereby contributing to citizen science. Therefore, experimental studies were conducted on a method of measuring flow velocity based on the simple physical phenomenon of rising water surface elevations due to increased pressure at the stagnation point. First, we placed the cylinders in the river or waterway, observed the afflux, and compared the velocities calculated using Bernoulli’s theorem with the velocities at the experimental site. By multiplying the calculated flow velocity by 0.9, the average flow velocity was found to be obtained. Then, by using a large pitot tube with a hole diameter of about 5 mm, the rise in water level in the pitot tube was measured using a pressure-type water level meter, and the flow velocity was calculated using the pitot tube theory and compared with the flow velocity at the location of the hole at the experimental site. By multiplying the calculated velocity by 1.04, the velocity at the location of the hole can be obtained. In addition, the same experiment was conducted using a pitot tube with a slit. The slit tube was placed vertically with the slit facing upstream. Measurements were taken in the same method as for the pitot tube velocity meter and compared to the velocity at that point. By multiplying the calculated flow velocity by 0.99, the average flow velocity at that location can be obtained. These results indicate that a flow velocity measurement method utilizing stagnation points can lead to the development of inexpensive velocity meters. Because of the simplicity of this meter, there is a possibility that citizens can participate in the observation to obtain information on the flow velocity during floods and areal information within a watershed.

A new flow velocity measurement method based on the ring electrostatic sensor

Gas-solid two phase flow widely lies in industry process, while its parameters measurement (flow velocity, the mass flowrate, particle sizes, et al.) is very difficult. This paper mainly studies the solid phase flow velocity measurement questions of gas-solid two phase flow with the ring electrostatic sensor. During the flow velocity measurement study, a new mathematical model of the electrostatic sensor is established, and by simulating the obtained model the spatial filter characteristics of the electrostatic sensor are obtained. By the spatial filter characteristics analysis of the ring electrostatic sensor, a new flow velocity measurement method is obtained in this paper. At last, some experiments are accomplished in the laboratory with line sand. The new method of measuring flow velocity is effective in these experiments. The flow velocity obtained with the new measuring method is calibrated with the cross-correlation velocity. When the line sand velocity is less than 7m/s, the repeatability error of the measured velocity is less than ± 10%.

A Flow Velocity Measurement Method Based on Turbulent Pressure Fluctuation Characteristics

In order to perform flow velocity measurements without interfering in the flow field itself, a flow velocity measurement method based on the characteristics (the rule by which the power spectrum varies with the flow velocity) of turbulent pressure fluctuations is proposed. This method is based on the characteristics of turbulent pressure fluctuations in the turbulent boundary layer (TBL) and uses a polyvinylidene fluoride (PVDF) sensor to convert pressure fluctuations into voltage outputs. First, TBL pressure fluctuation characteristics are studied. Second, the piezoelectric characteristics of PVDF piezoelectric sensors are studied and a sensor array signal processing method that can improve the signal-to-noise ratio is provided. Then, numerical simulations are performed to verify the characteristics of turbulent pressure fluctuations in the TBL. Finally, a PVDF sensor is made and flow velocity measurement experiments are performed. The results show that the power spectrum of the PVDF sensor response to excitation by turbulent pressure fluctuations is proportional to the fourth power of the flow velocity. It is feasible to use this characteristic to measure the flow velocity.

In-vivo full-field measurement of microcirculatory blood flow velocity based on intelligent object identification.

.Microcirculation plays a crucial role in delivering oxygen and nutrients to living tissues and in removing metabolic wastes from the human body. Monitoring the velocity of blood flow in microcirculation is essential for assessing various diseases, such as diabetes, cancer, and critical illnesses. Because of the complex morphological pattern of the capillaries, both in-vivo capillary identification and blood flow velocity measurement by conventional optical capillaroscopy are challenging. Thus, we focused on developing an in-vivo optical microscope for capillary imaging, and we propose an in-vivo full-field flow velocity measurement method based on intelligent object identification. The proposed method realizes full-field blood flow velocity measurements in microcirculation by employing a deep neural network to automatically identify and distinguish capillaries from images. In addition, a spatiotemporal diagram analysis is used for flow velocity calculation. In-vivo experiments were conducted, and the images and videos of capillaries were collected for analysis. We demonstrated that the proposed method is highly accurate in performing full-field blood flow velocity measurements in microcirculation. Further, because this method is simple and inexpensive, it can be effectively employed in clinics.

A novel particle tracking velocimetry method for complex granular flow field**Project supported by the National Natural Science Foundation of China (Grant Nos. 11572201 and 91634202).

Particle tracking velocimetry (PTV) is one of the most commonly applied granular flow velocity measurement methods. However, traditional PTV methods may have issues such as high mismatching rates and a narrow measurement range when measuring granular flows with large bulk density and high-speed contrast. In this study, a novel PTV method is introduced to solve these problems using an optical flow matching algorithm with two further processing steps. The first step involves displacement correction, which is used to solve the mismatching problem in the case of high stacking density. The other step is trajectory splicing, which is used to solve the problem of a measurement range reduction in the case of high-speed contrast The hopper flow experimental results demonstrate superior performance of this proposed method in controlling the number of mismatched particles and better measuring efficiency in comparison with the traditional PTV method.

Hhaynu micro hydropower scheme: Mbulu – Tanzania comparative river flow velocity and discharge measurement methods

The objective of the study has been to determine the river discharge by measuring the river flow velocity using two different measurement methods together with the area method and compare the accuracy of the results.Two river flow velocity measurement methods were used, the floating method and the use of current meter. In floating method a floating object was used to determine the water flow velocity on the surface by allow a float to move a distance of 1 m along the river and record the time it takes to travel that distance in seconds. Ten readings were taken and manually recorded and the flow velocity was determined by taking the distance travel by the float (1 m) divide by the time taken by the float (in seconds). On the other hand, the current meter method measure directly the average flow velocity across the river depth, twenty readings were taken and recorded manually and the average velocity were calculated. The use of current meter display flow velocity directly without the need of calculations.The result shows that both methods produce very close value, but the floating method have displayed higher value of around + 2% than current meter method which is a good value, despite the fact that floating method measures the surface velocity and the use of calculation. Many literature highlighted the accuracy of flow velocity measurement using current meter due to the fact that it measures the average velocity across the river, but from the findings when the floating method flow velocity measurement is properly applied it will produce as accurate results as the current meter with a fraction of cost in terms of instrument cost and expertise requirement in measurements.The floating method flow velocity measurement method could be applicable as alternative to current meter in micro hydropower projects river flow measurements in rural areas of developing countries with limited funding and local expertise.

Studi Kecepatan Aliran Air dengan Menggunakan Tabung Pitot

The tools and methods used in the measurement of water flow velocity are now very diverse, such as by using Venturi Meter, Orifice, Current Meter, Pitot Tube, and so forth. To learn more about water flow velocity measurement method, in order to improve professionalism in the field of water resources can be done research at Hydraulics Laboratory by researching Water Flow Analysis by Using Pitot Tubes. The research process will be carried out using three varied channel basis samples: reviewing the velocity of the water flow at the bottom of the channel with slippery base, reviewing the flow rate of the water on the gravel base channel, and reviewing the flow rate of the water on the channel with the decking concrete base. The expected result of this research is knowing the distribution of velocity in a cross section such as drainage channel, irrigation channel and river, so construction of water structure can be adjusted position placement in the open channel section. In addition it can be used as a reference in planning an open channel. One of the benefits to construction cofferdam construction speed distribution is to determine the dewatering system to be carried out during construction.Keywords— Flow Speed, Speed Distribution. Channel Basic Variations

Wide-field absolute transverse blood flow velocity mapping in vessel centerline.

We propose a wide-field absolute transverse blood flow velocity measurement method in vessel centerline based on absorption intensity fluctuation modulation effect. The difference between the light absorption capacities of red blood cells and background tissue under low-coherence illumination is utilized to realize the instantaneous and average wide-field optical angiography images. The absolute fuzzy connection algorithm is used for vessel centerline extraction from the average wide-field optical angiography. The absolute transverse velocity in the vessel centerline is then measured by a cross-correlation analysis according to instantaneous modulation depth signal. The proposed method promises to contribute to the treatment of diseases, such as those related to anemia or thrombosis.

Crowd-based velocimetry for surface flows

Flow velocity measurement is important in hydrology. Recently, owing to the popularity of sensors and processors, image-based flow velocity measurement methods have become an important research direction. Particle image velocimetry (PIV) is a key example. However, due to the uncertainty of the features, PIV sometimes provides very inaccurate results and always requires customized setups. In this research, we take advantage of the human perception system, that is, the strong abilities related to feature identification and tracking, in order to estimate the surface flow velocity of a river. We developed a method called crowd-based velocimetry (CBV) to incorporate the human perception capacity in the estimation of the flow velocity. CBV includes three main steps: (1) video processing, (2) crowd processing, and (3) statistical processing. We validated CBV by measuring a fast, steady, and uniform river surface flow in an artificial canal. The results show that compared to radar measurements from the center of the flow, CBV measured the surface flow velocity with a deviation ranging between +12.1% and +17.3% from the radar measurement, while PIV resulted in a −1.7% to −24.3% deviation. With rapidly improving mobile devices, CBV allows enormous numbers of people to engage in flow measurement, making CBV more reliable, more efficient, and more economical.

FLOW VELOCITY MEASUREMENT METHODS USING ELECTRICAL CAPACITANCE TOMOGRAPHY

The current methods of calculating the velocity field based on a twin-plane electrical capacitance system for multiphase flows are presented. The described methods allow to calculate the velocity profile of the multiphase flow in cross-section of industrial installation. The theoretical assumptions of the considered methods are also noticed. The main advantages and disadvantages of the authors’ flow velocity measurement methods are discussed.

Oil–water two-phase flow velocity measurement with continuous wave ultrasound Doppler

A flow velocity measurement method based on continuous wave ultrasound Doppler (CWUD) and flow profile modeling is presented. A theoretical model is proposed to relate the overall superficial velocity of oil–water two-phase flow with the mean velocity measured in the sensing volume of CWUD, by introducing velocity profile correlation. A CWUD measuring system was built to emit an ultrasonic wave of 1MHz and collect the frequency shift of the reflected waves. Dynamic experiments were carried out in a horizontal pipe of inner diameter of 50mm with the CWUD system. Six flow patterns of horizontal oil–water two-phase flow were observed including both the water continuous flow and the oil continuous flow. According to the results, the average frequency shift in oil–water two-phase flow varies with the flow pattern. The flow velocity correlations are separately established for the oil continuous dispersed flow, water continuous dispersed flow and stratified flow, based on the analysis of flow velocity profile correction. The average relative error of the overall superficial velocity is 3.63% with a maximum relative error of 12.22%.

Energy Demodulation Algorithm for Flow Velocity Measurement of Oil-Gas-Water Three-Phase Flow

Flow velocity measurement was an important research of oil-gas-water three-phase flow parameter measurements. In order to satisfy the increasing demands for flow detection technology, the paper presented a gas-liquid phase flow velocity measurement method which was based on energy demodulation algorithm combing with time delay estimation technology. First, a gas-liquid phase separation method of oil-gas-water three-phase flow based on energy demodulation algorithm and blind signal separation technology was proposed. The separation of oil-gas-water three-phase signals which were sampled by conductance sensor performed well, so the gas-phase signal and the liquid-phase signal were obtained. Second, we used the time delay estimation technology to get the delay time of gas-phase signals and liquid-phase signals, respectively, and the gas-phase velocity and the liquid-phase velocity were derived. At last, the experiment was performed at oil-gas-water three-phase flow loop, and the results indicated that the measurement errors met the need of velocity measurement. So it provided a feasible method for gas-liquid phase velocity measurement of the oil-gas-water three-phase flow.

Quantification of Ultrasound Correlation‐Based Flow Velocity Mapping and Edge Velocity Gradient Measurement

This study investigated the use of ultrasound speckle decorrelation- and correlation-based lateral speckle-tracking methods for transverse and longitudinal blood velocity profile measurement, respectively. By studying the blood velocity gradient at the vessel wall, vascular wall shear stress, which is important in vascular physiology as well as the pathophysiologic mechanisms of vascular diseases, can be obtained. Decorrelation-based blood velocity profile measurement transverse to the flow direction is a novel approach, which provides advantages for vascular wall shear stress measurement over longitudinal blood velocity measurement methods. Blood flow velocity profiles are obtained from measurements of frame-to-frame decorrelation. In this research, both decorrelation and lateral speckle-tracking flow estimation methods were compared with Poiseuille theory over physiologic flows ranging from 50 to 1000 mm/s. The decorrelation flow velocity measurement method demonstrated more accurate prediction of the flow velocity gradient at the wall edge than the correlation-based lateral speckle-tracking method. The novelty of this study is that speckle decorrelation-based flow velocity measurements determine the blood velocity across a vessel. In addition, speckle decorrelation-based flow velocity measurements have higher axial spatial resolution than Doppler ultrasound measurements to enable more accurate measurement of blood velocity near a vessel wall and determine the physiologically important wall shear.

Lateral blood flow velocity estimation based on ultrasound speckle size change with scan velocity

Conventional (Doppler-based) blood flow velocity measurement methods using ultrasound are capable of resolving the axial component (i.e., that aligned with the ultrasound propagation direction) of the blood flow velocity vector. However, these methods are incapable of detecting blood flow in the direction normal to the ultrasound beam. In addition, these methods require repeated pulse-echo interrogation at the same spatial location. A new method has been introduced which estimates the lateral component of blood flow within a single image frame using the observation that the speckle pattern corresponding to blood reflectors (typically red blood cells) stretches (i.e., is smeared) if the blood is moving in the same direction as the electronically-controlled transducer line selection in a 2-D image. The situation is analogous to the observed distortion of a subject photographed with a moving camera. The results of previous research showed a linear relationship between the stretch factor (increase in lateral speckle size) and blood flow velocity. However, errors exist in the estimation when used to measure blood flow velocity. In this paper, the relationship between speckle size and blood flow velocity is investigated further with both simulated flow data and measurements from a blood flow phantom. It can be seen that: 1) when the blood flow velocity is much greater than the scan velocity (spatial rate of A-line acquisition), the velocity will be significantly underestimated because of speckle decorrelation caused by quick blood movement out of the ultrasound beam; 2) modeled flow gradients increase the average estimation error from a range between 1.4% and 4.4%, to a range between 4.4% and 6.8%; and 3) estimation performance in a blood flow phantom with both flow gradients and random motion of scatterers increases the average estimation error to between 6.1% and 7.8%. Initial attempts at a multiple-scan strategy for estimating flow by a least-squares model suggest the possibility of increased accuracy using multiple scan velocities.

An improved method for shallow water flow velocity measurement with practical electrolyte inputs

summary The measurement of shallow water flow velocity is of interest to hill-slope hydrology and soil erosion mechanics. Lei et al. [Lei, T., Xia, W., Zhao, J., 2005. Method for measuring velocity of shallow water flow for soil erosion with an electrolyte tracer. Journal of Hydrology 301, 139–145] proposed an electrolyte pulse method for the purpose but found that the velocity measured at short distances from the salt injector was not as well estimated as those further away from the injector, though it is desirable to estimate velocity at short distances for the purpose of portable device development. In this study, the system was improved over the previous development. An additional sensor was added at the salt injection location to register the input signal as the actual boundary condition function instead of using the pulse assumption. Two function forms, a Normal distribution function (Normal Model) and a Sine function (Sine Model) were suggested to approximate the measured boundary conditions. These two determined boundary models were used to fit the experimentally obtained data using the least square method to determine the model parameters of the boundary conditions. The determined Normal Model and the Sine Model were both used to solve the transport processes as the convolution integrals of the pulse response and the actually determined boundary functions, so as to determine the shallow water flow velocity. Laboratory experiments were conducted to get data to verify the proposed methods and computational procedures. The experiment device included a flume, 4 m long and 15 cm wide, a solute injector, a data logger for control and data acquisition and a computer with specially designed software for data measurement and velocity estimation. The experiments involved three flow rates (12, 24 and 48 L min � 1 ) and three slope gradients (4 ,8 and 12). Six sensors were used to measure the solute transport processes at 5, 30, 60, 90, 120 and 150 cm from the location where the salt solute was injected into the water flow. The solutions of both the Normal Model and Sine Model fitted the measured data very well for all the experimental conditions. The velocities at different distances from the salt solution injector and under different flow rates and slope gradients, as computed by the two models were almost identical, which indicated the feasibility of the method and the computational procedures as well as the two suggested models for velocity estimation. The velocity values estimated by the Normal and Sine Models agreed also with those measured by using the floating objects and the volumetric method. These demonstrated the rationality of the improved methods for shallow water flow velocity measurement. The results will be useful to design a practical system for the measurement of shallow water flow velocity.

Ultrasound low-velocity flow estimations using cross-correlation and decorrelation: A thread phantom study

In this paper, two time-domain flow velocity measurement methods, cross-correlation and decorrelation, were implemented and compared in measuring low blood-flow velocities, ranging from 0.05 to 5 cm/s, at known beam-vessel angles of 50–90° in a thread phantom. Both methods achieved a significant correlation between the measured and the known velocities ( r = 0.99; P < 0.001) in the thread phantom measurements, at 50–70° beam-vessel angles. Although the cross-correlation method showed a significant correlation ( r > 0.99; P < 0.001), this method caused large errors (>45%) at 80° and 90°, whereas the decorrelation method not only achieved a significant correlation ( r > 0.99; P < 0.001) but also resulted in smaller errors (<19%) at 80° and 90°. This study demonstrates the potential of time-domain decorrelation method for measuring low flow velocity at large beam-vessel angles near perpendicular conditions.

Acoustic flowmeter for the measurement of the mean flow velocity in pipes.

This paper proposes a new technique for measuring the gas flow velocity averaged along the finite length of a pipe as well as over its cross-sectional area. Unlike the conventional gas flowmeters, the proposed technique exploits the one-dimensional plane waves that propagate uniformly across the pipe cross-sectional area. When a fluid flows along the pipe, the plane waves are superposed with the flow field such that the positive-going and negative-going plane wave components undergo the change of their wave numbers. Such wave number variation due to the mean flow velocity has provided a major motivation for developing a new way of measuring the mean flow velocity in the pipe, which is referred to as the acoustic flowmeter. To examine the feasibility of the developed flow velocity measurement method, including its theoretical backgrounds, experimental setups are illustrated in this paper. Detailed experimental data for the flow velocity range of 2-27 m/s reveal the linearity of the proposed acoustic flowmeter and its salient environmental robustness for the different acoustic pressure patterns in the pipe and, furthermore, for different velocity profiles over the pipe cross-section area.

Estimation of the correlation amplitude of RF signals in small cutaneous vessels

Time domain correlation technique is a widely used method for blood flow velocity measurement. The time shift between a pair of windowed ultrasonic echoes is estimated by searching the temporal position of the maximum of the interpolated normalized correlation function. Between two consecutive echoes, the acoustical footprint of a group of scatterers, which are transported with the flow, moves and is deformed. This implies a decreasing of the amplitude of the normalized correlation coefficient. In the case of microcirculation (low flow rate, low SNR), the amplitude of the correlation peak can be used to detect the presence of blood flow and to discriminate false and true detections (reliability index). We have numerically evaluated the statistical performances of the cross-correlation algorithm used as a correlation peak amplitude estimator in severe conditions (short correlation window length, low SNR). These theoretical results have been compared with in vitro experimentation on a 100-/spl mu/m-diameter microcirculatory phantom and with in vivo experimentation on a 180-/spl mu/m-diameter vessel of a human leg carrying erysipelas.