Velocity profiles and interface instability in a two-phase fluid: investigations using ultrasonic velocity profiler

Measurement of Joule-heating flow convection induced by internal heat generation using ultrasound velocity profiler in glycerin fluid

Oscillating pipe flow of a magnetic fluid was investigated experimentally by using the Ultrasonic Velocity Profiler (UVP) method. The test liquids are two kinds of water-based magnetic fluid W-40 and MSG11. UVP method is a useful technique for measuring the velocity components of a magnetic fluid. When this method is applied to magnetic fluid flow, it is necessary for the ultrasonic propagation velocity to be accurate. However, when an external magnetic field is applied to a magnetic fluid, some of the inner particles coagulate and form clustering structures. These clustering structures affect the ultrasonic propagation. Therefore, the properties of ultrasonic propagation in test magnetic fluids were also analyzed exactly before the measurement by UVP. Based on this analysis, UVP method is applied to magnetic fluid. In the result of velocity profile measurement, unique phenomena of oscillating pipe flow of the magnetic fluids subject to magnetic field were observed. It seems that the change of clustering structures under magnetic field cause these unique phenomena.

Estimating the number of transducers for flow rate measurement using the UVP method downstream of double elbows

An ultrasonic velocity profile (UVP) method has been successfully applied to the investigation of mercury flow contained in a stainless steel wall in the configuration of a liquid metal target of a spallation neutron source called SINQ at the Paul Scherrer Institute. One- and two-dimensional stationary flow has been fully investigated in the form of velocity profiles. Using velocity profiles obtained by the UVP method, a two-dimensional flow map was efficiently produced. A steady state vector map was successfully made and time dependent flow mapping is feasible.

Velocity measurement on Taylor–Couette flow of a magnetic fluid with small aspect ratio

This study presents a low-frequency ultrasonic propagation analysis using the finite-element method (FEM). Experimental results of flow rate measurements using the ultrasonic velocity profile (UVP) method are also presented. The ultrasound frequency, pipe diameter, and pipe wall thickness are 0.274 MHz, 590.6 mm, and 9.5 mm, respectively. Six waves are generated per ultrasound pulse. To analyze the entire pipe region, the FEM is combined with the Kirchhoff method. The experiments of flow rate measurements are conducted using the high Reynolds number calibration facility at the National Metrology Institute of Japan. The range of the Reynolds number is from 4.4×106 to 1.7×107. Wide spreading of the ultrasonic beam in the axial direction of the pipe is observed because of multiple reflections in the pipe wall. This wide beam affects the measured velocity profile, particularly in the region near the pipe wall. In addition, the flow rate errors are approximately 10% (deviating by 1.1%) across the investigated range of Reynolds number. This result suggests that the experimental flow rate errors might be used as correction factors of flow rate measurements using the UVP method.

Ultrasonic Velocity Profile (UVP) method is a measuring method with the velocity component along the ultrasonic beam. It is useful method as velocity profile measurement of an opaque fluid like a magnetic fluid. When we apply the ultrasonic method to some fluids, we have to obtain the ultrasonic propagation velocity in those fluids. However, ultrasonic propagation velocity in magnetic fluid has not been investigated in detail. In this present paper, we measured the ultrasonic propagation velocity in a magnetic fluid precisely and analyzed the influence of the chain like cluster under magnetic field on the ultrasonic propagation velocity. On the basis of these results, oscillating pipe flow of a magnetic fluid was investigated experimentally by the UVP method.

Two-phase bubbly flow is a common phenomenon in many industrial processes. To understand its characteristic, the velocity profile of liquid and bubble are necessary to be known accurately. The ultrasonic velocity profile (UVP) method has been known as a nonintrusive measurement method that can measure velocity profiles of fluid. Although the original UVP can measure velocity profile of two phase bubbly flow, it cannot distinguish liquid and bubble velocity. Therefore, the separation technique is used to overcome this limitation. The aim of this study was to develop signal processing of UVP method to measure liquid and bubble velocity profiles separately. Short Time Fourier Transform (STFT) was proposed to be applied in this case, and it was paralleled with other signal processing techniques. The experiment was conducted on vertical pipe flow apparatus. The velocity profile measurement in two-phase bubbly flow was performed. Separation of liquid and bubble velocity was demonstrated. Moreover, the method was compared with other techniques experimentally.

The authors have carried out a study to investigate and clarify the characteristics of purely oscillating pipe flows over the developing region. The main objective of this study is to establish the method of time-dependent velocity profiles obtained by the ultrasonic velocity profile (UVP) measurement method. First, the relationship between the test fluids and the microparticles, as reflectors of ultrasonic pulses, was investigated. In addition, the relationship between the sound speeds of the test fluids and the wall materials was studied. Second, the UVP was used to obtain the instantaneous velocity profiles in oscillating pipe flows, and the developing characteristics of the flows were analyzed. Finally, the “entrance length” (by analogy with a unidirectional pipe flow) required for oscillating pipe flows was analyzed by examining the amplitude of the harmonic spectral components of the oscillating frequency. A fast Fourier transform (FFT) is proposed as the applicable method to estimate the “entrance length”. From the Fourier transform of the velocity on the centerline, nonlinear oscillation of fluid occurs in the “entrance length” of the oscillating flows, and the viscous dissipation of the higher-order velocity harmoncis determines the entrance region. The “entrance length” can be obtained from the dissipation length of the third-order harmonic. These results prove that the UVP method is highly applicable to carry out the flow measurement in the “entrance length” of oscillating pipe flow.

This paper presents a new estimation method to determine the optimal number of transducers using an Ultrasonic Velocity Profile (UVP) for accurate flow rate measurement downstream of a single elbow. Since UVP can measure velocity profiles over a pipe diameter and calculate the flow rate by integrating these velocity profiles, it is also expected to obtain an accurate flow rate using multiple transducers under nondeveloped flow conditions formed downstream of an elbow. The new estimation method employs a wave number of velocity profile fluctuations along a circle on a pipe cross-section using Fast Fourier Transform (FFT). The optimal number of transducers is estimated based on the sampling theorem. To evaluate this method, a preliminary experiment and numerical simulations using Computational Fluid Dynamics (CFD) are conducted. The evaluating regions of velocity profiles are located at 3 times of a pipe diameter () for the experiment, and 1 and for the simulations downstream of an elbow, respectively. Reynolds numbers for the experiment and simulations are set at and , respectively. These results indicate the efficiency of this new method.

An ultrasonic velocity profile (UVP) method can measure instantaneous one-dimensional velocity profile along the measuring line. It is non-intrusive technique, and it can be easily applied for existing facilities. The UVP method utilizes the ultrasonic Doppler frequency reflected on tracer particles for obtaining the velocity. For analyzing the Doppler frequency, there are some algorithms such as Fast Fourier Transform (FFT), auto-correlation, and so on. However, the influence of the algorithms on measuring velocity profile has not been investigated. In this study, difference of the algorithms for velocity measurements was investigated using a developed system. It consists of an ultrasonic pulser-receiver which transmits and receives ultrasonic waves, a high-speed digitizer which records wave data, and a PC which analyzes and calculates velocity. FFT and auto-correlation method were used for the calculation. In case of the FFT, there are 2 methods to calculate the Doppler frequency. One is a method to calculate the frequency of maximum value in the power spectral density (PSD), and the other is a method to calculate the average value of the frequency in the PSD. Velocity distributions were compared to a laser Doppler velocimeter (LDV), and the appropriate algorithms were chosen depending on the flow conditions. From the results, it was clarified that the auto-correlation method could reduce the number of ultrasonic repetition for the measurement.

The ultrasonic velocity profile measurement method has some favorable advantages over the conventional flow measurement methods, such as measurement of the instantaneous velocity profile over the measuring line and its applicability to opaque liquids. The method has another advantage of being non-intrusive. Hence, it is applicable to various flow conditions, although it requires a relatively large measurement volume. In this paper, the effects of the measurement volume on the mean velocity profile and the Reynolds stress measurement have been investigated for fully developed turbulent flows in a vertical pipe. The results were then compared with data obtained by direct numerical simulation.

Simultaneous measurement of liquid velocity and interface profiles of horizontal duct wavy flow by ultrasonic velocity profile meter

Contractile floating barriers for confinement and recuperation of oil slicks

An ultrasonic velocity profile (UVP) method has been successfully applied to the investigation of a liquid metal channel flow under the influence of an inhomogeneous magnetic field. Using velocity profiles obtained by the ultrasonic velocimeter and their numerical post processing, two-dimensional time-averaged flow maps were efficiently produced. A single transducer immersed directly into the working fluid was used in order to simplify alignment of measurement lines and avoid the undesirable refraction of the acoustic beam on the walls. An M-shaped flow and wake behind a magnetic obstacle were reconstructed as the patterns of shear and large-scale vortical flows.