Ultrasonic Pulsed Doppler Method Research Articles

Applicability evaluation of the ultrasonic pulse-train Doppler method on the disturbed flow in a pipe

This manuscript presents an experimental study to evaluate the applicability of the ultrasonic pulse-train Doppler method (UPTD) to the disturbed flow in a pipe. The UPTD can expand the detectable velocity range compared with the conventional ultrasonic pulse Doppler method and has an advantage of trouble-free installation into conventional hardware. Comparative experiments were conducted using two different transducer frequencies, 1 MHz and 4 MHz. The UPTD was only applied to the 4-MHz condition to expand the velocity range fourfold, which is equal to the velocity range of a 1-MHz transducer. The probability density distributions of the measured velocities were almost the same between 1 MHz and 4 MHz, even though the measurement position was not only downstream of a long straight pipe but also downstream 10 or 5 pipe diameters from an obstacle plate. To estimate the influence of aliasing on the velocity measurement for a large fluctuating flow, experiments using a 2-MHz transducer were also conducted. These results indicated that it is possible to estimate the standard deviation of the velocities measured under the aliasing condition, and the accuracy of flow rate measurement decreases when the standard deviation of the velocity exceeds the measurable velocity by approximately twice. Additionally, the flow rate by the 1-MHz transducer was about −2% smaller than that by the 4-MHz transducer for both the straight pipe and disturbed conditions. Through the validation of the influence of the measurement volume between 1 MHz and 4 MHz conditions, the flow rate difference was found to be likely due to the influences of not only the measurement volume but also the standing wave formed by the pulses reflected on the opposite pipe wall.

Experimental study to establish an evaluating method for the responsiveness of liquid flowmeters to transient flow rates

An aim of this research work is to establish an evaluation method concerning a responsiveness of flowmeters for a transient flow rate. To this end, reference flow metering systems for the transient flow are proposed in this paper. Because a behavior of the responsiveness depends on the type of flowmeter, evaluations using different parameters, such as response time to sudden rise and sudden fall in flow rate, response to the frequency and amplitude of flow pulsation, mean characteristic and so on are needed. To achieve a precise evaluation, two reference flow metering methods for transient flow rates are proposed in this paper. One is a high-response weighing method and the other is a velocity profile measurement method using the ultrasonic pulsed Doppler method (UPDM). Since the behaviors of the transient flow rate measured by both methods show good agreement, we conclude them to be useable as a reference flow metering system.

Experimental study for transient flow rate measurement by means of ultrasonic pulsed Doppler method

This paper reports the investigations of the transient flow rate of the several flow meters and the ultrasonic flowmeter based on the pulsed Doppler method. The reference flow rate is given by the gravimetric method which is newly established in NMIJ. The flow rates are investigated for pulsation flow with 0.5 Hz – 8 Hz frequency. The fluctuations of flow rate by ultrasonic pulsed Doppler method and Coriolis flowmeter are agreed well each other and with the reference flow rate. The influence of the fluctuation of flow rate is less than 2% for the pulsed Doppler method. The result gives new advantage, which is high response for transient flow, for the ultrasonic flowmeter based on the pulsed Doppler method.

Application of partial inversion pulse to ultrasonic time-domain correlation method to measure the flow rate in a pipe

This paper proposes the application of a novel ultrasonic pulse, called a partial inversion pulse (PIP), to the measurement of the velocity profile and flow rate in a pipe using the ultrasound time-domain correlation (UTDC) method. In general, the measured flow rate depends on the velocity profile in the pipe; thus, on-site calibration is the only method of checking the accuracy of on-site flow rate measurements. Flow rate calculation using UTDC is based on the integration of the measured velocity profile. The advantages of this method compared with the ultrasonic pulse Doppler method include the possibility of the velocity range having no limitation and its applicability to flow fields without a sufficient amount of reflectors. However, it has been previously reported that the measurable velocity range for UTDC is limited by false detections. Considering the application of this method to on-site flow fields, the issue of velocity range is important. To reduce the effect of false detections, a PIP signal, which is an ultrasound signal that contains a partially inverted region, was developed in this study. The advantages of the PIP signal are that it requires little additional hardware cost and no additional software cost in comparison with conventional methods. The effects of inversion on the characteristics of the ultrasound transmission were estimated through numerical calculation. Then, experimental measurements were performed at a national standard calibration facility for water flow rate in Japan. The experimental results demonstrate that measurements made using a PIP signal are more accurate and yield a higher detection ratio than measurements using a normal pulse signal.

Development of ultrasonic pulse-train Doppler method for velocity profile and flowrate measurement

We present a novel technique for measuring the velocity profile and flowrate in a pipe. This method, named the ultrasonic pulse-train Doppler method (UPTD), has the advantages of expanding the velocity range and setting the smaller measurement volume with low calculation and instrument costs in comparison with the conventional ultrasonic pulse Doppler method. The conventional method has limited measurement of the velocity range due to the Nyquist sampling theorem. In addition, previous reports indicate that a smaller measurement volume increases the accuracy of the measurement. In consideration of the application of the conventional method to actual flow fields, such as industrial facilities and power plants, the issues of velocity range and measurement volume are important.The UPTD algorithm, which exploits two pulses of ultrasound with a short interval and envelope detection, is proposed. Velocity profiles calculated by this algorithm were examined through simulations and excellent agreement was found in all cases. The influence of the signal-to-noise ratio (SNR) on the algorithm was also estimated. The result indicates that UPTD can measure velocity profiles with high accuracy, even under a small SNR.Experimental measurements were conducted and the results were evaluated at the national standard calibration facility of water flowrate in Japan. Every detected signal forms a set of two pulses and the enveloped line can be observed clearly. The results show that UPTD can measure the velocity profiles over the pipe diameter, even if the velocities exceed the measurable velocity range. The measured flowrates were under 0.6% and the standard deviations for all flowrate conditions were within ±0.38%, which is the uncertainty of the flowrate measurement estimated in the previous report. In conclusion, UPTD provides superior accuracy and expansion of the velocity range.

UVPの計測速度限界拡張と流量計測への応用

The ultrasonic velocity profile (UVP) method is a powerful tool for measuring velocity profiles in a pipe and it has been applied for measuring flow rate. In this paper, a velocity extension method for use with ultrasonic pulsed Doppler method is introduced to increase the maximum detectable velocity which is limited by the Nyquist sampling theorem. The measurement volume is shown to be among the important parameters that must be considered in assessing the traceability of the reflector during the pulse emission interval. Hence, a larger measurement volume is required to measure higher velocities. In order to improve the flow rate accuracy, multi-wave ultrasonic method is introduced. The velocity profiles in the near-wall region are measured using an 8-MHz sensor with a small diameter, while those far from the transducer are measured using a hollow 2-MHz sensor in the multi-wave transducer. The techniques are shown to be particularly effective for measuring higher flow rates in a large-diameter pipe.

Multi-wave ultrasonic Doppler method for measuring high flow-rates using staggered pulse intervals

The ultrasonic pulsed Doppler method (UDM) can obtain a velocity profile along the path of an ultrasonic beam. However, the UDM measurement volume is relatively large and it is known that the measurement volume affects the measurement accuracy. In this study, the effect of the measurement volume on velocity and flow rate measurements is analytically and experimentally evaluated. The velocities measured using UDM are considered to be ensemble-averaged values over the measurement volume in order to analyze the velocity error due to the measurement volume, while the flow rates are calculated from the integration of the velocity profile across the pipe. The analytical results show that the channel width, i.e. the spatial resolution along the ultrasonic beam axis, rather than the ultrasonic beam diameter, strongly influences the flow rate measurement. To improve the accuracy of the flow rate, a novel method using a multi-wave ultrasonic transducer consisting of two piezo-electric elements with different basic frequencies is proposed to minimize the size of the measurement volume in the near-wall region of a pipe flow. The velocity profiles in the near-wall region are measured using an 8 MHz sensor with a small diameter, while those far from the transducer are measured using a hollow 2 MHz sensor in the multi-wave transducer. The applicability of the multi-wave transducer was experimentally investigated using the water flow-rate calibration facility at the National Institute of Advanced Industrial Science and Technology (AIST). As a result, the errors in the flow rate were found to be below −1%, while the multi-wave method is shown to be particularly effective for measuring higher flow rates in a large-diameter pipe.

A dealiasing method for use with ultrasonic pulsed Doppler in measuring velocity profiles and flow rates in pipes

The ultrasonic pulsed Doppler method (UDM) is a powerful tool for measuring velocity profiles in a pipe. However, the maximum detectable velocity is limited by the Nyquist sampling theorem. Furthermore, the maximum detectable velocity (also called Nyquist velocity), vmax, and the maximum measurable length are related and cannot be increased at the same time. If the velocity is greater than vmax, velocity aliasing occurs. Hence, the higher velocity that occurs with a larger pipe diameter, i.e. under higher flow rate conditions, cannot be measured with the conventional UDM. To overcome these limitations, dual-pulse repetition frequency (dual PRF) and feedback methods were employed in this study to measure velocity profiles in a pipe. The velocity distributions obtained with the feedback method were found to be more accurate than those obtained with the dual PRF method. However, misdetection of the Nyquist folding number using the feedback method was found to increase with the flow velocity. A feedback method with a moving average is proposed to improve the measurement accuracy. The method can accurately measure the velocity distributions at a velocity five times greater than the maximum velocity that can be measured with the conventional UDM. The measurement volume was found to be among the important parameters that must be considered in assessing the traceability of the reflector during the pulse emission interval. Hence, a larger measurement volume is required to measure higher velocities using the dual PRF method. Integrating velocity distributions measured using the feedback method with a moving average makes it possible to accurately determine flow rates six times greater than those that can be determined using the conventional pulsed Doppler method.

Measurement of Bubbly Two-phase Flow in Vertical Pipe Using Multiwave Ultrasonic Pulsed Dopller Method and Wire Mesh Tomography

Abstract Two measurement methods which are multiwave ultrasonic pulsed Doppler (multiwave UVP) method and wire mesh tomography (WMT) have been applied to the measurement of bubbly two-phase flow. Velocity profiles of bubbles and liquid have been measured using multiwave UVP. Simultaneously, cross-sectional void fraction distribution has been measured using WMT. As the result, a combination method has been set up. The measured parameters are indispensable in order to obtain detailed structures of two-phase flow. Multiwave UVP method exploits two basic ultrasonic frequencies which are 2 MHz and 8 MHz. Simultaneous measurement of velocity profiles of bubbles (using 2 MHz frequency) and those of liquid (using 8 MHz frequency), at the same position, is enabled. A multiwave ultrasonic transducer (multiwave TDX) which is able to emit and receive the two ultrasonic frequencies along the measurement line at the same time has been applied. The signal processing is based on the pulsed Doppler method. Using the combination method, first, instantaneous velocity profiles and void fraction distribution have been measured simultaneously for air-water counter-current bubbly flow in a vertical pipe. Flow structure has been clarified. Effect of initial condition on void fraction distribution has been confirmed. Next, measurements have been carried out for subcooled boiling bubbly flow in a vertical pipe. For measurement of subcooled boiling flow, a high temperature wire mesh sensor (WMS) has been developed. A method for separation of velocity profiles of bubbles with different sizes and velocities has been suggested.

0402 超音波パルスドップラ法の計測速度限界拡張による測定精度への影響評価

0402 超音波パルスドップラ法の計測速度限界拡張による測定精度への影響評価

ICOPE-15-1040 A new method for high flow rate measurement using ultrasonic multi-wave pulsed Doppler method with staggered trigger

ICOPE-15-1040 A new method for high flow rate measurement using ultrasonic multi-wave pulsed Doppler method with staggered trigger

Effects of the number of pulse repetitions and noise on the velocity data from the ultrasonic pulsed Doppler method with different algorithms

The ultrasonic pulsed Doppler technique known as the ultrasonic velocity profile (UVP) method has been widely used in many engineering fields. The analysis algorithms of the UVP, the number of pulse repetitions (Npulse), noise and reflector conditions, etc. all affect the measurement accuracy. Npulse is related to the temporal resolution, thus to improve this resolution it must be set as low as possible. However, it is known that the measurement accuracy of the instantaneous velocity becomes worse with decreasing values of Npulse. In this study, UVP analysis algorithms including the fast Fourier transform (FFT), autocorrelation, and the wavelet transform (WT) were compared via simulations and experiments using varying values of Npulse and the signal-to-noise ratio (SNR). We show that there is an appropriate Npulse for each algorithm that depends on the SNR; specifically, the value of Npulse increases with decreasing SNR. The difference between the algorithms for the velocity data was small under low noise conditions. However, a FFT with a Gaussian interpolation produced the best result under noisy conditions. In contrast the WT was relatively unaffected by noise. Therefore, a WT is the preferred choice for measuring velocity distributions if high sampling measurement is not required.

Ultrasound Pulsed Wave Doppler Imaging of the Esophagus Illustrates the Effects of Water Volume on Bolus Kinematics

AbstractThis study aimed to elucidate the effects of water volume on flow properties of bolus (passage time and velocities) at the esophagus orifice using ultrasonic pulsed wave Doppler method. Five healthy males and five females were asked to consume 3, 6, 9 and 12 mL water in a single swallow. An ultrasound probe was placed against each subject's neck to observe the flow properties of bolus. The velocity spectra of the bolus at the esophagus orifice were analyzed. Our results revealed that velocity of bolus was easily affected by volume of water, and the passage time and velocities increased as the increase in volume.Practical ApplicationsUltrasonography, using a medical ultrasound instrument, is an effective method for observing bolus kinematics during swallowing. The velocity spectra of bolus can be visualized for different volume of water using the pulsed wave Doppler method. When a bolus of food is swallowed, aspiration that the bolus partly enters the trachea instead of the esophagus may occur. Water is known to show a high possibility of aspiration. This study revealed that reducing volume of water decreases the passage time and velocities of bolus at the esophageal entrance. Therefore, this technique can be used for designing the texture of food materials for people who experience aspiration or suffocation by food.

Development of Multiwave Method Using Ultrasonic Pulse Doppler Method for Measuring Two-phase Flow

Development of Multiwave Method Using Ultrasonic Pulse Doppler Method for Measuring Two-phase Flow

GS03 超音波流速分布計測法を用いた高流量計測手法の開発

Ultrasonic pulsed Doppler method (UDM) can obtain velocity profile on the ultrasonic beam path. By integrating the velocity profile over the pipe, flow-rate can be derived with high accuracy. In order to measure higher velocity by using feedback method, the larger measurement volume is required. With increasing of the measurement volume, it has been reported that the measurement accuracy near-wall region becomes low. In order to improve the measurement accuracy, multi-wave ultrasonic method which employs two ultrasonic sensors with basic frequency of 2 & 8 MHz is proposed. The velocity distribution was accurately obtained over the pipe by combining velocity distributions at 8 MHz for the near-wall region and 2 MHz for the region far from the transducer. Furthermore, the accuracy of the flow-rate was also improved with the proposed method.

Measurements of single-phase and two-phase flows in a vertical pipe using ultrasonic pulse Doppler method and ultrasonic time-domain cross-correlation method

Ultrasonic Velocity Profile (UVP) method for measurement of single-phase and two-phase flow in a vertical pipe has recently been developed in the Laboratory for industrial and Environmental Fluid Dynamics, Institute of Mechanics, VAST. The signal processings of the UVP method include the ultrasonic pulse Doppler method (UDM)and the ultrasonic time-domain cross-correlation (UTDC) method. For two-phase flow, simultaneous measurements of both liquid and gas are enabled by using a multi-wave ultrasonic transducer (multi-wave TDX). The multi-wave TDX is able to emit and receive ultrasound of two different center frequencies of 2 MHz and 8 MHz at the same time and position. 2 MHz frequency with beam diameter 10 mm is exploited for measurement of gas. 8 MHz one with beam diameter 3 mm is used for liquid. Measurements have been carried out for laminar and turbulent single-phase flows and bubbly counter-current two-phase flows in two flow loops using two vertical pipes of 26 mm inner diameter (I.D.) and 50 mm I.D. respectively. Based on the measured results, assessment of each method is clarified. Applicability of each method for different conditions of pipe flow has been tested. Suggestions for application of the two methods have been recommended.

研究 超音波パルス・ドプラ法による狭窄弁口面積の非侵襲的測定法

研究 超音波パルス・ドプラ法による狭窄弁口面積の非侵襲的測定法

Effect of Number of Pulse Repetition and Noise on Velocity Profile Measurement in Ultrasonic Pulse Doppler Method

Ultrasonic pulse Doppler method has been widely used in many engineering field referred to as UVP (ultrasonic velocity profiler). Analysis algorithm in the UVP, number of pulse repetition (Npulse), noise and reflector conditions, etc. may affect on the measurement accuracy. The Npulse is related to the temporal resolution, and must be set as low as possible in order to improve the temporal resolution. However, it is known that accuracy of instantaneous velocity becomes worse with decreasing of the Npulse. In this study, effect of analysis algorithm in the UVP on velocity data was investigated with changing of the Npulse and SNR by simulation and experiments. As a result, it is shown that there is an appropriate Npulse in each algorithm depending on the SNR. An algorithm which decides the Doppler frequency from maximum value in the power spectrum, FFT-max, was relatively hard to be affected by noise. Difference of velocity standard deviation was small between lower and higher noise conditions when FFT-max with Npulse over the appropriate value was used for the calculation. Hence, FFT-max was the best analysis algorithm for measuring flow field compared with the autocorrelation.

Relationship between the Parameters obtained by 2-bite Texture Profile Analysis (TPA) and the Velocity through the Pharynx Measured by the Ultrasonic Pulse Doppler Method

2-バイトTPA（Texture Profile Analysis）試験から求められるパラメータと咽頭部通過時の食物の流速との関係について検討した．TPA試験は，厚生労働省の「えん下困難者用食品」の基準法に準拠して行ったが，プランジャー速度については，基準にある10 mm/sに加えて1 mm/sについても検討を行った．得られたTPA曲線から3つのパラメータ「硬さ」（hardness），「付着性」（adhesiveness），「凝集性」（cohesiveness）を求めた．咽頭部の流速は，超音波パルスドプラー法により測定した．3つのパラメータの中では「硬さ」が，誤嚥の危険性の尺度と報告のある咽頭部最大流速Vmaxとの相関が最も高く，嚥下困難者用介護食の指標として適していると考えられた．一方，「凝集性」は，試料の性状によって変化し，咽頭部流速分布との相関がみられなかった．このことは，「えん下困難者用食品」の基準にある試料を円筒容器に入れての測定が液状の試料には妥当でないことを示唆している．3つのパラメータに対するVmaxのプロットの形はプランジャー速度10 mm/sと1 mm/sであまり変わらなかった．このことから，TPA試験におけるプランジャー速度に関しては，装置依存性があまりないという報告のある1 mm/sの方が10 mm/sより適していることが示唆された．

The Basic Study of Ultrasound Characteristics and Velocimetry in Molten Glass

High temperature measurement system is presented. This system employs the ultrasonic buffer rod and pulsed Doppler method. The buffer rod has a cooling jacket to use the high efficiency room temperature transducer. For considering ultrasonic velocimetry method in the molten borosilicate glass, the temperature dependency of sound velocity at the temperature of 1000°C to 1200°C is obtained using cross-correlation technique, and its difference is within plus-minus 5%. A numerical simulation is also applied to design the optimised buffer rod, and its result shows good agreement with an experiment. Using this technique, the velocity, especially the speed of relative moving wall is obtained, and its error is within plus-minus 4% when a value remained in measurable velocity.