Salinity and flow regime independent multiphase flow measurements

For oil production fields, there is a need for downhole measurements of the gas/water/oil multiphase flow. In extreme conditions a relatively simple, robust, and non-intrusive system will be appropriate. A measurement setup that combines multiple gamma beam (MGB) and dual modality densitometry (DMD) measurements, would be able to determine the gas volume fraction (GVF) independently of the flow pattern, and monitor changes in water salinity. MGB measurements of gamma-ray transmission along multiple sections across the oil pipe will provide information on the flow pattern. Whereas the DMD principle will give information on changes in salinity from a combination of transmission and scattering gamma-radiation measurements. In this work we present the results from MGB and DMD measurements of a multiphase flow with high-speed gamma-ray tomograph measurements as reference for the flow pattern. The MGB measurements should enable us to distinguish between stratified or wavy/slug and annular or slug flow. Flow patterns with several minor components distributed evenly over the measurement cross section, like bubble flow, will be interpreted as homogeneous flow. The DMD measurements can be used to monitor salinity changes of the water component for intervals where the GVF is low and the water cut of the liquid is high. Combined with other gauges for water cut measurements, the MGB and DMD measurement setup should improve the multiphase flow measurements, and enable increased oil/gas recovery and production water monitoring.     

Experimental investigation of gas-liquid flow in a vertical venturi installed downstream of a horizontal blind tee flow conditioner and the flow regime transition

A venturi device is commonly used as an integral part of a multiphase flowmeter (MPFM) in real-time oil-gas production monitoring. Partial flow mixing is required by installing the venturi device vertically downstream of a blind tee pipework that conditions the incoming horizontal gas-liquid flow (for an accurate determination of individual phase fraction and flow rate). To study the flow-mixing effect of the blind tee, high-speed video flow visualization of gas-liquid flows has been performed at blind tee and venturi sections by using a purpose-built transparent test rig over a wide range of superficial liquid velocities (0.3–2.4 m/s) and gas volume fractions (10–95%). There is little ‘homogenization’ effect of the blind tee on the incoming intermittent horizontal flow regimes across the tested flow conditions, with the flow remaining intermittent but becoming more axis-symmetric and predictable in the venturi measurement section. A horizontal (blind tee) to vertical (venturi) flow-pattern transition map is proposed based on gas and liquid mass fluxes (weighted by the Baker parameters). Flow patterns can be identified from the mean and variance of a fast electrical capacitance holdup measured at the venturi throat.     

Experimental and numerical study of the sweep effect on three-dimensional flow downstream of axial flow fans

The purpose of this work is to study the influence of the axial flow fan sweep on the downstream turbulent flow. The fans studied are three low-pressure and low-Mach-number axial flow fans, with respectively a radial, a forward and a backward sweep. Experimental and computational fluid dynamics (CFD) investigations are carried out on three fans, and the results are compared. The CFD method is a three-dimensional (3D) Reynolds average Navier–Stokes (RANS) numerical simulation with the Reynolds stress model (RSM) as the turbulence model. It allows us to compute the Reynolds stress tensor components. Unsteady velocity measurements are carried out downstream of the fans with hot-wire anemometry. The values of the three velocity components of the flow and the six components of the Reynolds stress tensor obtained from experiments and simulations are compared. Overall performances are also measured to validate the design and fan simulation. It appears that a forward sweep decreases the radial component of the velocity whereas a backward sweep increases this component. Moreover, the sweep has a significant influence on the turbulent kinetic energy downstream of the fan.     

Analysis of flow distribution from high-speed flow actuator using particle image velocimetry and digital speckle tomography

A variety of active flow control (AFC) methods are typically used in low-speed applications; however, the AFC techniques that are available for high-speed, supersonic applications are very limited. Under AFOSR (Air Force Research Laboratory) sponsorship, The Johns Hopkins University Applied Physics Laboratory (JHU/APL) is investigating a device that is intended for high-speed flow control; it is called the SparkJet actuator, which manipulates high-speed flows without active mechanical components. To date, actuator characterization has included computational and experimental techniques including parametric studies and flow visualization techniques to investigate the operation of the SparkJet device under various conditions. This paper focuses on the experimental flow measurement techniques that have been implemented. The results will be used for validating prospective computational studies that investigate the detailed characteristics of the SparkJet’s discharge and cooling stages after an energy deposition pulse. Current efforts include the use of high- resolution particle image velocimetry (PIV) to quantify the quiescent air operation of a single SparkJet pulse. However, the proper seeding of the SparkJet cavity continues to be challenging and has led to the use of digital speckle tomography (DST) to measure the temperature distribution in the core of the SparkJet plume. In this study, improved PIV techniques were used to acquire a higher-resolution image of the SparkJet-entrained flow. These PIV results show that the peak velocity in the entrained flow is around 53 m/s and the plume is sustained for 75–100 μs. Additionally, the DST data show a peak temperature of 1616.3 K at 75 μs and provide supporting information for interpreting the PIV data. These results are intended to calibrate and build confidence in a computational model.     

Doppler spectrum analysis and flow pattern identification of oil-water two-phase flow using dual-modality sensor

Horizontal oil-water two-phase flow widely exists in petroleum and chemical engineering industry, where the oil and water are usually transported together. As one of most importance process parameters to describe the two-phase flow, the flow pattern can reflect the flow characteristics of inner flow structure and phase distribution. The identification of flow pattern will contribute to develop more accurate measurement model for flow rate or phase fraction and ensure the safety and efficiency of operation in industry. A dual-modality sensor combining with continuous wave ultrasonic Doppler sensor (CWUD) and auxiliary conductance sensor, was proposed to identify flow patterns in horizontal oil-water two-phase flow. In particular, the oil-water flow characteristic was analyzed from Doppler spectrum based on the CWUD sensor. Besides, the dimensionless voltage parameter based on conductance sensor was applied to provide the information of continuous phase in the fluid. Several statistical features were directly extracted without any complicated processing algorithm from Doppler and conductance signals. The extracted features are put into a multi-classification Support Vector Machine (SVM) model to classify five oil-water flow patterns. The results show that the overall identification accuraccy of 94.74% is satisfactory for horizontal oil-water two-phase flow. It also demonstrates that the noninvasive ultrasonic Doppler technique not only can be used for flow velocity measurement but also for flow pattern identification.     

Influence of flow disturbances on the performance of industry-standard LNG flow meters

In the last decade significant progress has been achieved in the development of measurement traceability for LNG inline metering technologies such as Coriolis and ultrasonic flow meters. In 2019, the world's first LNG research and calibration facility has been realised thus enabling calibration and performance testing of small and mid-scale LNG flow meters under realistic cryogenic conditions at a maximum flow rate of 200 m³/h and provisional mass flow measurement uncertainty of 0.30% (k = 2) using liquid nitrogen as the calibration fluid. This facility enabled, for the first time, an extensive test programme of LNG flow meters under cryogenic conditions to be carried out to achieve three main objectives; the first is to reduce the onsite flow measurement uncertainty for small and mid-scale LNG applications to meet a target measurement uncertainty of 0.50% (k = 2), the second is to systematically assess the impact of upstream flow disturbances and meter insulation on meter performance and the third is to assess transferability of meter calibrations with water at ambient conditions to cryogenic conditions. SI-traceable flow calibration results from testing six LNG flow meters (four Coriolis and two ultrasonic, see acknowledgment section) with water in a water calibration facility and liquid nitrogen (LIN) in the LNG research and calibration facility under various test conditions are fully described in this paper. Water and LIN calibration data were compared and it was observed that the influence of removing the meter insulation on mass flow rate measurement accuracy can be more significant (meter error > ±0.50%) than the influence of many typical upstream disturbances when the meter is preceded by a straight piping length equal to twenty pipe diameters (20D) with no additional flow conditioning devices, in particular for ultrasonic meters. The results indicate that the correction models used to transfer the water calibration to cryogenic conditions (using LIN) can potentially result in mass flow rate measurement errors below ±0.5%, however, the correction models are specific to the meter type and manufacturer. This work shows that the target measurement uncertainty of 0.50% can be achieved if the expanded standard error of the mean value measured by the meter is smaller than 0.40% (k = 2). It is planned to repeat these tests with LNG in order to compare the results with the LIN tests presented in this paper. This may reveal that testing with an explosion safe and environmentally friendly fluid such as LIN produces representative results for testing LNG flow meters.     

Design and validation of a uniform flow microreactor

We present a design method to characterize uniform flows in a microreactor for high performance surface plasmon resonance (SPR) a general-purpose biosensor chips. The shape of the microreactor is designed based on an approximate pressure drop model. The number of micro-pillars and the slopes of the inlet and outlet linear chambers are two dominant parameters used to minimize the velocity difference in the microreactor. The flow uniformity was examined quantitatively by numerical and experimental visualization methods. A computational fluid dynamics (CFD) analysis demonstrates that the designed microreactor has a fairly uniform velocity profile in the reaction zone for a wide range of flow rates. The velocity field in the fabricated microreactor was measured using the micro-particle image velocimetry (μ-PIV) method, and the flow uniformity was confirmed experimentally. The performance of the uniform flow microreactor was verified using the fluorescence antibody technique.     

T型管流场混合多相流与欧拉多相流模型的数值研究

以计算流体动力学(CFD)的多相流数值计算理论及方法为基础,对处于复杂工况的T型管连接装置腔内流场进行了数值模拟分析,采用标准湍流模型和标准壁面函数对T型管接头内部流场进行了数值模拟;同时以混合模型求得的解作为用欧拉多相流模型的初始条件,采用欧拉多相湍流模型进行了对T型管接头内部流场数值计算.最后对两种模型计算得到的T型管接头内部流场的压力场、速度场及气相的体积分数(VOF)分布进行了对比分析.计算结果将指导的结构优化设计及失效分析.     

Pressure drop and flow distribution characteristics of single and parallel serpentine flow fields for polymer electrolyte membrane fuel cells

This study numerically investigates pressure drop and flow distribution characteristics of serpentine flow fields (SFFs) that are designed for polymer electrolyte membrane fuel cells, which consider the Poiseuille flow with secondary pressure drop in the gas channel (GC) and the Darcy flow in the porous gas diffusion layer (GDL). The numerical results for a conventional SFF agreed well with those obtained via computational fluid dynamics simulations, thus proving the validity of the present flow network model. This model is employed to characterize various single and parallel SFFs, including multi-pass serpentine flow fields (MPSFFs). Findings reveal that under-rib convection (convective flow through GDL under an interconnector rib) is an important transport process for conventional SFFs, with its intensity being significantly enhanced as GDL permeability increases. The results also indicate that under-rib convection can be significantly improved by employing MPSFFs as the reactant flow field, because of the closely interlaced structure of GC regions that have different path-lengths from the inlet. However, reactant flow rate through GCs proportionally decreases as under-rib convection intensity increases, suggesting that proper optimization is required between the flow velocity in GCs and the under-rib convection intensity in GDLs.     

Identification of gas-liquid flow regimes using a non-intrusive Doppler ultrasonic sensor and virtual flow regime maps

The accurate prediction of flow regimes is vital for the analysis of behaviour and operation of gas/liquid two-phase systems in industrial processes. This paper investigates the feasibility of a non-radioactive and non-intrusive method for the objective identification of two-phase gas/liquid flow regimes using a Doppler ultrasonic sensor and machine learning approaches. The experimental data is acquired from a 16.2-m long S-shaped riser, connected to a 40-m horizontal pipe with an internal diameter of 50.4 mm. The tests cover the bubbly, slug, churn and annular flow regimes. The power spectral density (PSD) method is applied to the flow modulated ultrasound signals in order to extract frequency-domain features of the two-phase flow. Principal Component Analysis (PCA) is then used to reduce the dimensionality of the data so as to enable visualisation in the form of a virtual flow regime map. Finally, a support vector machine (SVM) is deployed to develop an objective classifier in the reduced space. The classifier attained 85.7% accuracy on training samples and 84.6% accuracy on test samples. Our approach has shown the success of the ultrasound sensor, PCA-SVM, and virtual flow regime maps for objective two-phase flow regime classification on pipeline-riser systems, which is beneficial to operators in industrial practice. The use of a non-radioactive and non-intrusive sensor also makes it more favorable than other existing techniques.     

Uncertainty estimation of a liquid flow standard system with small flow rates

A liquid flow standard system is used to calibrate liquid volume of fuel–oil flow meters at small flow rates between 50 L/h and 700 L/h. However, the system has not been used to calibrate volume flow rate because the system is only operated with the standing-start-and-finish mode. In this study, the liquid flow standard system was rebuilt to provide a calibration service of volume flow rate by attaching two flow diverters, which can operate the system with the flying-start-and-finish mode. To evaluate its performance for volume flow metering, several techniques were introduced. First, diverter timing errors were estimated by linear regression. Second, covariance between buoyancy correction factor and water density was obtained to consider interdependency between the two measurands. Third, calibration and measurement capability (CMC) was evaluated by setting a fixed value of collected weight or elapsed time for flow diversion. Finally, several CMCs were compared to find the best measurement condition. As a result of the above approach, the CMC of the liquid flow standard system was found to be (0.10–0.52)% (k = 2) for (50–700) L/h with a minimum collected weight at 10 kg.     

动态压差控制阀流场及流量控制特性研究

针对变流量加热及冷却系统水力和热力失调的问题,设计一种动态压差控制阀.基于计算流体力学(CFD)方法,建立不同阀芯开度下动态压差控制阀三维流道模型.对比研究了不同阀芯开度下阀内流场分布以及流量变化,得出了动态压差控制阀在不同阀芯开度下阀内压降曲线的变化规律、阀芯节流口处速度曲线及湍动能曲线的分布规律,拟合了阀门出口流量...     

Effect of high beta values on mass flow through critical flow nozzles

In a previous work (Stewart et al., Flow Measurement and Instrumentation 10(1) (1999) 27–34) the authors presented improved calculations for the mass flow of a gas through a critical flow nozzle. The work in Stewart et al. is applicable only when the nozzle throat to pipe diameter ratio, β, is low (<0.15). Whilst it is preferable to use a critical flow nozzle with a low β, practical considerations may dictate otherwise. This work extends the calculations to include high β values, explaining the problems encountered in these situations and the procedure for calculating the mass flow accordingly. The same four gases are covered, dry CO₂-free air, nitrogen, argon, and methane. A new empirical correction factor for use with high β critical flow nozzles is presented which, when combined with the work in Stewart et al., provides an accurate yet simple method for calculating the mass flow of these gases through critical flow nozzles with a wide range of β values.     

Multiphase flow measurements using coupled slotted orifice plate and swirl flow meter

Multiphase flow metering is a major focus for oil and gas industries. The performance of a modified version of a close coupled slotted orifice plate and swirl flow meter for multiphase flow was evaluated to provide further development of a new type of multiphase flow meter. The slotted orifice provides well homogenized flow for several pipe diameters downstream of the plate. This characteristic provides a homogeneous mixture at the inlet of the swirl meter for a wide range of gas volume fractions (GVF) and flow rates. In order to evaluate the performance of the designed flow-meter, its response was investigated for varying pressures and water flow rates. The proper correlations were established to provide high accurate two-phase flow measurements. The new proposed approach provides the GVF measurement with less than ±0.63% uncertainty for GVF range from 60% to 95%.     

Mass flow rate measurement of gas-liquid two-phase flow using acoustic-optical-Venturi mutisensors

The measurement of multiphase flow parameters is essential for the online monitoring of industrial production and energy metering. In this paper, a multi-sensor experimental measurement device is designed based on NIR, acoustic emission sensors, and throated Venturi. The measurement information is decomposed using modal decomposition, and the characteristic variables of the gas volume fraction are extracted by flow noise decoupling and light attenuation analysis. A new gas volume fraction model is proposed based on Gradient Boosting Decision Tree (GBDT) through feature-level fusion, and the Mean Absolute Percentage Error (MAPE) of the gas volume fraction prediction models is within 4% for the three flow patterns. A new flow rate model is established based on the Homogeneous and Collins models. Laboratory results indicate that the MAPE of the flow rate model is 1.56%, and 98.61% relative deviations are within ±20% error band. The study provides a new method for online measurement of multiphase fluid motion and a theoretical basis for sensing mechanism and measurement of multiphase flow.     

Scaling in combined plastic flow and fracture

The scaling laws are given for bodies undergoing simultaneous plastic flow and crack propagation, deformations which can be adequately described by rigid-plastic fracture mechanics. The laws depend on (i) a material-dependent term given by the ratio of plastic work done/volume ∫σ dε to the material fracture toughness R for the given pattern of deformation, as well as on (ii) a geometrical term given by the ratio, in the reference model structure, of the volume of material plastically deformed, V, to the crack area, A. The two contributing factors are combined in a single non-dimensional parameter . Energy scaling in prototype (p) and model (m) follows

Full-size image (<1K)

, which is the true form of λ^x-type empirical relations < 3; for fracture alone, V = 0, so ξ = 0 and x = 2; for plastic flow without fracture A = 0, so ξ = ∞ and x = 3. Associated scaling relationships for loads, stresses and displacements between model and prototype are also given. All scaling relations are functions of ξ, which is an arbitrary parameter, since it depends on the particular size chosen for the reference model structure. That is, the magnitude of the ratio of scaled quantities (and value of x in λ^x empirical relations) depends on the absolute size of the model. The reason for this curious state of affairs is found in the coordinate geometry of the linear plot of ( ) vs ( ) which is central to rigid-plastic fracture mechanics. The new scaling laws agree well with a wide range of quasi-static and dynamic experimental data on scaled bodies. They help to explain hitherto anomalous behaviour in the impact of scaled structures.     

Effects of flow patterns and salinity on water holdup measurement of oil-water two-phase flow using a conductance method

This research investigates the effects of flow pattern and salinity of oil-water two-phase flow on water holdup measurement using a conductance method. Firstly, vertical upward oil-water two-phase flow experiment is conducted in a 20 mm inner diameter (ID) pipe, in which the salinities of aqueous solutions are set as 151 ppm, 1003 ppm, 2494 ppm and 4991 ppm respectively. Experimental water-cut and mixture velocity are set as 80–100% and 0.0184–0.2576 m/s. In the experiment, three different flow patterns, i.e., dispersed oil-in-water slug flow (D OS/W), dispersed oil-in-water flow (D O/W) and very fine dispersed oil-in-water flow (VFD O/W) are observed and recorded by a high speed camera. Meanwhile, we collect the response of Vertical Multiple Electrode Array (VMEA) conductance sensor excited by a sine voltage signal. The result shows that, for VFD O/W, the water holdup from VMEA sensor shows a satisfied agreement with that of quick closing valve (QCV) method under certain salinities, i.e., 1003 ppm as well as 2494 ppm. For D OS/W flow and D O/W flow characterized by dispersed oil droplets with various sizes, considerable deviations of water holdup between VMEA sensor and QCV method under four kinds of salinity aforementioned are presented. Afterward, according to experimental analysis along with theoretical deviation, it is concluded that the deviation of the measurement system reaches its minimum when reference resistance in the measurement circuit and salinity of the aqueous solution satisfy constraint conditions, and the accuracy of water holdup using the conductance method can be improved through adjusting reference resistance to match the salinity of water phase. Finally, the recurrence plot algorithm is utilized to identify typical flow patterns mentioned above and it shows satisfied results on comprehending the discrepancies among different flow patterns, demonstrating that the recurrence plot algorithm can be effectively applied in flow pattern identification regarding oil-water flows.     

Liquid hydrocarbon flow meters calibration with high flow and viscosity: Conceptual design of a new facility

The oil and natural gas production market is heavily regulated with specifications that are almost always defined and valid for each producing country. In all the focus is to ensure accurate and complete results in volumes produced but with specificities of each location. In Brazil this regulation was created in the year 2000 (Joint Ordinance No. 001 between the National Petroleum Agency - ANP and the National Institute of Metrology, Quality and Technology - INMETRO) and in the 2013 review it was specified that liquid hydrocarbon flow meters should be calibrated with fluid under the conditions closest to those found in the operation considering density, viscosity, flow, pressure and temperature. However, the type of oil produced in Brazilian fields typically has high viscosity and there is an additional aspect due to the use of FPSO (Floating Production Storage and Offloading) type production platforms: flow to tankers occurs at high flow rates. There are several restrictions in laboratories worldwide to meet these conditions (high viscosity with high flow) and so the purpose of this paper is to present a proposal that technically meets the conditions imposed by Brazilian regulations and that will serve as a reference for operations in other similar fields. The project considers the laboratory should be able to perform calibrations up to 3200 m^3/h, oil densities above 0.88, with flexibility for changing calibration fluid, pressure and temperature control and viscosities up to 700 cP. To this end, a broad evaluation was carried out with solution providers and a research group within the university to technical support     

风选通道分析及优化设计

为了提高城市生活垃圾中废塑料在风选通道内的分选率,分析了轻质垃圾在分选通道内理想化运动形式,运用流体力学知识以及fluent软件对通道内的气流速度,气流分布形式进行了仿真分析。根据仿真分析以及物料在气流场中的运动规律,对通道形状进行改进,并对改进后的通道内的气流场进行仿真分析。对筛面上方通道出口端的风速及方向进行了分析,这对筛面上物料的运动分析有很大意义。经过通道气流场的分析,以及通道形状的改进,对提高废塑料分选率以及研究筛面上物料的运动状态有重大社会意义、经济意义。     

Work flow control in the flexible flow line

This research involves the development and evaluation of a part flow control model for a type of flexible manufacturing system (FMS) called a dedicated flexible flow line (FFL). In the FFL, all part types flow along the same path between successive machine groups. The specific objective of the part flow control model for the FFL is to minimize makespan for a given set of parts produced in a FFL near-term schedule, given fixed available buffer constraints. The control model developed in this research involved the repeated, real-time execution of a mathematical programming algorithm. The algorithm attempts to release the right mix of parts at the tight time to keep the FFL operating smoothly. The focus of the approach is directed toward managing WIP buffers for each machine group queue. The algorithm specifically incorporates stochastic disturbance factors such as machine failures. Through a limited number of simulation experiments, performance of the control model is shown to be superior to other parts releasing and control methods reported in the literature.