Flow Measurement and Instrumentation最新文献

Slug flow, characterized by the distinctive interfacial structures of Taylor bubbles surrounded by liquid films and bridged by aerated liquid slugs, is a dynamically complex two-phase flow pattern exist in many oil and gas, and energy systems. Accurate and precise quantification of such complex flow behaviour is essential for optimal design, safe operation, and reliable modelling of these systems. Existing image-based measurement techniques mostly rely on offline image processing algorithms and are often limited to a narrow set of flow characteristics primarily focusing on Taylor bubbles. Such constraints not only impede real-time flow monitoring and regulation but also leave liquid slug characteristics unmeasured, resulting in an inability to accurately determine the flow characteristics and extract instantaneous void fraction signals. Present study examined the performance of adaptive thresholding (AT) and background subtraction (BS) algorithms in capturing slug flow characteristics. It was found that while the former excels in Taylor bubbles detection and the latter in small bubbles identification, neither individually addresses the accurate measurement of both flow structures' characteristics. This observation, along with the mentioned restrictions of existing algorithms are the main reason for developing the present combined machine vision-based algorithm. While unlocking the ability to extract instantaneous void fraction signals, this new approach facilitates online measurement of a wide range of key flow characteristics, including Taylor bubble length, velocity, void fraction, and surrounding liquid film thickness; liquid slug length and void fraction; and slug unit length, void fraction, and frequency. Parallel to the high-speed imaging, time-series void fraction data was collected using two capacitance sensors installed alongside the imaging area on the pipe, providing benchmark data essential for the validation of the new algorithm's accuracy. The comparisons demonstrated a high degree of accuracy and precision for the combined algorithm. Quantitatively, the new algorithm measured key unit cell characteristics with RMS errors ranging from 2 to 10 %, while the BS and AT algorithms exhibited wider RMS error ranges of 8–46 % and 2–53 %, respectively. This underscores the new algorithm's potential as a transformative tool for slug flow analysis.

To enhance the working performance of the axial piston motor, computational fluid dynamics (CFD) software was employed to investigate the flow field characteristics of the axial piston motor. This paper presents a new type of damping groove and conducted three-dimensional computational fluid dynamics transient simulations on the unequal and new damping groove designs of the distribution plate. Pressure, flow rate fluctuation, and cavitation phenomena were measured under various structural parameters to verify the simulation results. The experimental results indicate that a well-designed distribution plate can not only reduce the pressure fluctuation of the motor but also enhance its anti-cavitation performance. Additionally, appropriately adjusting the structural parameters of the damping groove can effectively suppress the cavitation phenomenon to a certain extent. This can efficiently reduce the noise and vibration caused by cavitation, thereby significantly improving the reliability and lifespan of the axial piston motor.

In order to further explore the physical mechanism of rotating stall induced by different rim leakage flow intensification, the velocity distribution of the stall flow field of the mixed flow pump under different rim clearance scales was obtained by Particle Image Velocimetry technology. By comparing the flow structure under different shooting sections, different phases and different working conditions, the influence of rim clearance scale on the flow field near the wall of the mixed flow pump was revealed. The results show that under the design flow conditions, there is an obvious reflux phenomenon near the hub of the guide vane inlet of the mixed flow pump under the four kinds of rim clearance, but the intensity is weak, and it does not affect the main flow field in the impeller channel. With the increase of rim clearance scale, the leakage flow intensity also increases, and the main flow area affected by the TLV structure also increases. In the deep stall condition, the reflux vortex at the inlet of the guide vane of the mixed flow pump still exists at each clearance, but the unsteady flow structure begins to appear inside, especially the large secondary vortex structure formed at the guide vane inlet, which seriously blocks the main flow. With the increase of the rim clearance, the flow field at the inlet of the guide vane is also obviously affected, and the secondary vortex core gradually moves towards the end wall area, resulting in an increase in the blocked area in the flow field. At the same time, the unsteady flow intensity of the flow field shows a nonlinear increasing trend. The unsteady strength of flow field increases rapidly with small gap impellers, while the unsteady strength changes slowly with large gap impellers. This study provides a reference for optimizing the rim clearance of mixed-flow pump and improving the efficiency of mixed-flow pump.

To optimize production strategy, monitor reservoir performance, and maximize economic recovery of oil and gas fields, it is very important to accurately measure the separate phase flow of each fluid in multiphase flow. Due to the complexity of multiphase flow, the traditional method of measuring the flow per phase is challenging. The Spinner Array Tool (SAT) and equidistant area-weighted average method are used to predict the average fluid velocity of oil-water two-phase flow in horizontal wells. The slippage model is used to calculate the total volume flow of the fluid and the volume flow of each fluid. We collected mini-spinner sensing data in a Spinner Array Tool (SAT) for the oil-water two-phase and used the response characteristics of the single-phase fluid as reference data before mixing. The experimental results show that the isometric area-weighted average method can better process the sensor data of the Spinner Array Tool (SAT), and obtain better phase separation flow accuracy under different flow conditions. The predicted oil flow is in good agreement with the measured oil flow. The results show that it is feasible to infer the prediction results of the fractional flowrate from the prediction results of the average fluid velocity in the actual production logging.

While multiphase flows are abundant in both natural environments and engineering applications, their analysis and quantification present challenges. In particular, simultaneously measuring the flow field and quantifying particle behavior pose many challenges. Methods based on Particle Image Velocimetry (PIV) and Particle Tracking Velocimetry (PTV) principles have been used in the last two decades to measure flow fields and dispersed (particle) phases, respectively. Despite the extensive application of these principles to multiphase flow, there are numerous approaches and techniques used to synchronize and combine PIV and PTV measurements. Combined PIV and PTV data acquisition also requires consideration of phase discrimination to obtain distinct data for the fluid and dispersed phases. In the literature, various methods have been proposed and applied to achieve phase discrimination. This review paper aims to consolidate and classify various phase discrimination techniques used in specialized applications in hydraulic engineering. These methods are categorized into optical (spectral, temporal, and hybrid) and post-processing methods, with a particular emphasis on their applicability within the realm of hydraulic engineering. Moreover, this review expands on several emerging PIV/PTV technologies and applications, where the combination of equipment and algorithms has led to significant strides in the non-intrusive measurement of multiphase flow. By consolidating and critically evaluating current methods for particle discrimination, this paper aims to enhance the scientific community's understanding of simultaneous phase velocity measurements, thereby setting the stage for advancements in multiphase flow visualization techniques.

This article introduces a method for creating custom-made spherical fluorescent particles tailored for fluid mechanics optical velocimetry laboratory measurements techniques such as Particle Image Velocimetry (PIV) and Particle Tracking Velocimetry (PTV) measurement techniques. The incorporation of the fluorescent dye Rhodamine B into the particle bulk significantly reduces direct light reflections and enhances particle detection when enlightened by a laser and using a band-pass filter on the optical measurement device. Furthermore, the study offers a clear guide for adjusting particle diameter by modifying various parameters such as the stirrer used, its stirring speed, the surfactant concentration, and the type of polymer. This allows for the customization of particles best suited for water multiphase flow characterization and transport studies. The resulting particles exhibit excellent sphericity, making them suitable for a wide range of fluid mechanics investigations, from small to large scale. Experimental validations, including size measurements, density assessments, emission spectra analyses, and applicability in a confined flow affirm the effectiveness of the proposed methodology by exhibiting a signal-to-noise ratio four to five times higher than fluorescent surface-stained and non-fluorescent particles.

A robust hydraulic system is necessary for industrial gluing equipment in order to transfer and regulate a variety of chemical fluid media. Certain operational conditions call for a certain flow output. In hydraulic systems, pressure reduction valves are frequently employed to regulate flow and pressure output. In order to analyze the flow of high viscosity special media inside the valve body, a colloidal medium that complies with the power-law constitutive law and a novel type of pressure-reducing valve appropriate for high viscosity fluids were chosen as the research objects in this study. First, the valve channel's flow performance and flow field characteristics were researched with a combination of simulation and experiments. Then the impact of pressure differences, opening, and temperature variations on flow rate was investigated. The proposed flow prediction formulas can be used to forecast the flow rate in engineering applications accurately which is verified by the comparison of the numerical and experimental results. Lastly, an analysis was done on the pressure reducing valve's capacity to regulate pressure under various operating circumstances. The research can offer a specific reference for the analysis of flow field characteristics inside valves in high viscosity media and the design of pressure-reducing valve bodies in non-Newtonian media. Furthermore, the research results can help determine whether the pressure reducing valve's operating condition is normal.

In order to investigate the influence of different charging structures on the ignition performance and its influence on the particle movement before and after the film rupture of the chamber, a visualization experiment platform of the chamber was designed and built, and the stage tests of the ignition of the full particle charging, partial particle charging, mixed before and after the rod-particle charging and the full rod charging were carried out. The experiment shows that the free space will cause the flame propagation speed to increase significantly, from 77 m/s in the charge area to 575 m/s, and there will be pressure fluctuations in several areas of the chamber. The ignition performance of the rod is obviously better than that of the granular, and the pressure fluctuation in the chamber is smaller, the peak ignition gas pressure in the rod charge structure is only 50 % of that in the granular charge structure (1.6 MPa:3.2 MPa), and the maximum pressure difference is only 20 % of that in the granular propellant structure (0.5 MPa:2.5 MPa). The rod-particle mixed charge bed has good ignition consistency in the rod charge area, and when it reaches the granular charge area, the flame will be significantly hindered. The rod basically stays still during the ignition process in the chamber, while the granular will move with the gas flow when there is free space, and after the film is broken, the particle movement is faster than that before the film is broken.

Axial pumps were extensively applied in many varying applications because of their large flow and low head. In this research investigation, the comparative analysis of the findings unveiled that the predominant source of hydraulic-induced vibration in the pump stemmed from pressure pulsations at the impeller inlet. Notably, similar patterns in amplitude were observed as flow rates increased. Furthermore, time-domain analysis confirmed that pressure pulsations and vibrations are highly correlated under high flow rates. Pressure pulsation's Frequency-domain analysis also revealed that it was a multiple of shaft frequency and changed from one multiple to three multiples of vibration. While analyzing the flow rate characteristics pertaining to pressure pulsation and vibration, it was determined that pressure pulsations at the impeller inlet had the potential to generate frequency components across a broad spectrum, encompassing both low and high flow rates, as well as their respective multiples. This phenomenon was particularly pronounced in regions characterized by unstable and high flow rates. Vibration ingredients likely influenced by pressure pulsation at the impeller inlet could be as low as design flow rates and as high as high flow rates. A vibration frequency with a multiple did not seem to be influenced by pulsating pressure at the impeller entrance. The present study focuses on investigation of flow behaviors in an axial pump with varying numbers of blades. It is an important geometric parameter that significantly affects the pump's performance. Therefore, the dynamic flow patterns in a pump, considering changed flow and impeller blade configurations, are investigated by employing the sliding mesh technique in combination with SST (k-ω) turbulence model. The numerical results exhibit a commendable alignment with the existing experimental data, enhancing the predictive accuracy of pump performance. Qualitative analyses encompass static pressure, shear stress, and various velocity components. Concurrently, quantitative investigations delve into pressure fluctuations and average pressure across a spectrum of operating conditions and impeller blade configurations. These comprehensive findings underscore the substantial influence of the impeller blade on pressure, velocity magnitudes radial, axial, tangential shear stress, average pressure within the system.

The paper presents an invariant flow rate measurement system for individual components for a flow that consists of oil, water, and gas. The proposed flow measurement system is a continuation of the work of the authors, which is based on the application of the multichannelling principle of invariance theory. The paper proposes and discusses the structure of the invariant system for measuring the flow rate of oil-water-gas, analytical expressions are obtained for the implementation of algorithms for measuring the flow rate of individual substances that make up the flow. The uncertainty of the flow rate measurement results was assessed separately for oil, water, and gas. In this work, it is shown that by selecting flow meters of the main and additional channels with an uncertainty of less than 0.5 %, for almost any ratio of components in the additional pipeline, it is possible to measure the flow rate of water or oil with an uncertainty of less than 3 %, and the flow rate of the gas fraction in free form can be measured with an uncertainty value of less than 1 %. The paper discusses the practical aspects of the implementation of an industrial prototype of the system and the characteristics that affect its accuracy and efficiency.