Two-phase Flow Rate Research Articles

Construction of Solid-Liquid Two-Phase Flow and Wear Rate Prediction Model in Multiphase Pump Based on Mixture Model-Discrete Phase Model Combination Method

Blade wear is the critical problem in the operation of multiphase pump. This paper presents a numerical study of the multiphase flow of multiphase pump. The trajectory of particles in the pump is calculated by the discrete phase model. Then, the simulation results are compared with the model test results of the pump to verify the correctness of the simulation method. The results show that the particles in the impeller domain are mainly near the hub, and the particles in the diffuser domain form a agglomerated area in the middle of the flow channel. The average wear rate of the impeller is more affected by the particle size than that of the diffuser. The maximum wear rate of blade surface increases first and then decreases with the increase of particle size. According to the wear data under different particle sizes, the regression model between particle size and wear rate is fitted to predict the wear of mixed transport pump in actual operation. The research results have important reference value for the prediction of the wear performance of the multiphase pump.

Study on gas–liquid sulfonation reaction under annular flow pattern in micro-reactor: Mechanism, model and process optimization

Micro-sulfonation is a new sulfonation method with great development potential. The gas–liquid micro-sulfonation are safe, efficient and low-cost, however, limited by the research progress and application scope of micro-reactors, the development of gas–liquid micro-sulfonation technique is far from enough. The gas–liquid sulfonation reaction process under annular flow pattern in micro-reactor is experimentally studied in this paper. The maximum MESA (fatty acid methyl ester sulfonic acid) yield under the experimental conditions in this study achieves 89.771 %, which is obviously higher than that (64.1 % for gas–liquid sulfonation and 76.82 % for liquid–liquid sulfonation) in conventional reactors and should be higher if the micro-reactor structure or operating conditions being further optimized. Based on the analyses of experimental results, the effect mechanisms of mass transfer and reaction on the gas–liquid micro-sulfonation efficiency are explored, and the sulfonation efficiency models and pressure drop model of four micro-reactors are established by dimensional analysis method. On account of both the mass transfer characteristics of gas–liquid two-phase flow and the high-viscosity of sulfonation products, enhancing the local disturbance of liquid phase can significantly improve the reaction efficiency. Finally, the operating conditions of two-phase flow rates and reaction time are optimized to ensure the high sulfonation product yield meanwhile reduce the fluid pressure drop or energy consumption of sulfonation process using the improved NSGA-II algorithm.

Numerical investigation and rapid prediction of the erosion rate of gate valve in gas-solid flow

Gate valves are essential control components in pneumatic conveying systems and often experience erosion on their sealing structures due to impacts from solid particles. The erosion leads to a degradation of the sealing effectiveness and, in severe cases, system malfunction. To address this issue, a numerical model based on computational fluid dynamics (CFD) is developed for the simplified two-dimensional gate valve. The two-way Euler-Lagrange method is utilized to investigate the characteristics of gas-solid two-phase flow and erosion rate. The simulation procedure is verified by comparing the simulation results with experimental data. Results show that the sealing surface separates the free shear layer above the cavity and a low-velocity zone is created on the sealing surface. The particles moving at the downstream bottom are the main particles that impact the sealing surface. The erosion results show that the maximum erosion rate occurs near the top of the sealing surface. And the low-velocity zone reduces the erosion rate within that region. Particle diameter, gas velocity, and valve opening have an important effect on erosion on the sealing surface. The erosion rate increases as the valve opening decreases. The value of the maximum erosion rate increases with particle diameter and gas velocity, and its position changes. Finally, based on the established numerical model, a prediction model for the sealing surface erosion rate is constructed using the surrogate model approach.

Characteristic parameters measurement and flow prediction of slug flow based on ultrasound technology

Slug flow exists over a wide range of gas and liquid flow rates. For the case of smaller liquid volume fraction, this paper proposes a method for accurately identifying the flow structure of horizontal pipe slug flow based on the ultrasonic inner wall echo signal at the top of the pipe. The arrival and departure time of the slug is determined by analyzing the amplitude of the inner wall echo signal from both the test signal and reference signal and the rate of change of the test signal, respectively. Based on the accurate flow structure identification results, characteristic parameters can be calculated including the length ratio between the liquid film zone and the slug unit (lf/lu) and the average liquid film thickness in the liquid film zone (hf). The system of equations describing the relationship between the two parameters and the two-phase flow rates is constructed. By solving it, the flow rates of gas and liquid can be predicted. Experiments are carried out with the superficial velocity of gas and liquid ranging from 0.8 to 2.5 m/s and 0.1 to 0.4 m/s, respectively, where the pipeline’s inner diameter is 50 mm. The experimental results indicate that the mean absolute percentage errors for the predicted gas and liquid flow rates are 12.9605 % and 6.3517 %, respectively.

Simulating Two-Phase Seepage in Undisturbed Soil Based on Lattice Boltzmann Method and X-ray Computed Tomography Images.

The two-phase seepage fluid (i.e., air and water) behaviors in undisturbed granite residual soil (U-GRS) have not been comprehensively studied due to a lack of accurate and representative models of its internal pore structure. By leveraging X-ray computed tomography (CT) along with the lattice Boltzmann method (LBM) enhanced by the Shan-Chen model, this study simulates the impact of internal pore characteristics of U-GRS on the water-gas two-phase seepage flow behaviors. Our findings reveal that the fluid demonstrates a preference for larger and straighter channels for seepage, and as seepage progresses, the volume fraction of the water/gas phases exhibits an initial increase/decrease trend, eventually stabilizing. The results show the dependence of two-phase seepage velocity on porosity, while the local seepage velocity is influenced by the distribution and complexity of the pore structure. This emphasizes the need to consider pore distribution and connectivity when studying two-phase flow in undisturbed soil. It is observed that the residual gas phase persists within the pore space, primarily localized at the pore margins and dead spaces. Furthermore, the study identifies that hydrophobic walls repel adjacent fluids, thereby accelerating fluid movement, whereas hydrophilic walls attract fluids, inducing a viscous effect that decelerates fluid flow. Consequently, the two-phase flow rate is found to increase with then-enhanced hydrophobicity. The apex of the water-phase volume fraction is observed under hydrophobic wall conditions, reaching up to 96.40%, with the residual gas-phase constituting 3.60%. The hydrophilic wall retains more residual gas-phase volume fraction than the neutral wall, followed by the hydrophobic wall. Conclusively, the investigations using X-ray CT and LBM demonstrate that the pore structure characteristics and the wettability of the pore walls significantly influence the two-phase seepage process.

Gas-liquid flow and mass transfer characteristics in improved heart-shaped structure microreactor

The gas-liquid two-phase flow and mass transfer characteristics in heart-shaped structure microreactor were visually investigated in an Advanced Flow Reactor (AFR). Three various flow patterns were observed in the experiment: Taylor-bubble flow, Taylor-flow, and unstable broken flow. The experiment observed that the bubbles only broke steadily under the action of the first heart-shaped unit obstacle; while in the latter heart-shaped units, the larger bubbles would break resulting in the unstable broken flow. The efficiency of CO2 absorption increases as the gas-liquid two-phase flow rate ratio decreases and the solution concentration rises. The volume mass transfer coefficient increases with the increase of the gas-liquid two-phase flow rate ratio and the solution concentration. The absorption efficiency and mass transfer coefficient in channel 2 with two rows of heart-shaped units is greater than channel 1 with one row of heart-shaped units. Additionally, there exists an optimal performance ratio for reactor under the appropriate gas-liquid flow rate ratio.

Investigations on affinity law under gas–liquid conditions in multistage radial and mixed-flow multiphase pumps

Affinity laws have been widely used in pump design and simulation under high-temperature and corrosive conditions. By applying such laws, it is possible to shorten development cycles and reduce test costs. However, current applications of affinity laws are still limited to liquid conditions. In this paper, expressions for affinity laws and their applicability are investigated for multistage radial and mixed-flow multiphase pumps under gas–liquid conditions. A high-pressure (30 MPa) gas–liquid experimental platform is constructed, and three-stage and 25-stage radial pumps and a 15-stage mixed-flow pump are investigated, with specific speeds of 107 and 216. With gas compressibility taken into account, the gas–liquid two-phase flow rate, head, and power, and the corresponding dimensionless hydraulic coefficients, are defined for multiphase pumps. The deterioration of gas–liquid pressurization performance is found to be divided into three processes with different dynamic mechanisms, corresponding to three flow patterns. The inlet gas volume fraction of pump is used to judge dynamic similarity. At the same inlet gas volume fractions λ1 = λ2, when the gas–liquid flows in two pumps have the same flow pattern, dynamic similarity will be satisfied. The affinity law that is established shows good applicability to the three-stage radial multiphase pump, with goodness of fit R2 larger than 0.9 for the two-phase Ψm–Φm and Πm–Φm performance curves. Finally, experimental results indicate that the affinity law also has good applicability to multiphase pumps with different stage numbers and blade structures under gas–liquid conditions.

Measurement of high water-cut heavy oil flow based on differential pressure of swirling flow

Real-time measurement of heavy oil production is critical to ensure stable production. Due to the complex kinematic characteristics of heavy oil, existing methods cannot accurately measure its flow rate and water cut. In this paper, a novel method is proposed to measure the high water-cut heavy oil flow by using the differential pressure of the two-phase swirling flow in the pipe. For the swirling flow in the pipe, the radial differential pressure and the axial differential pressure exist simultaneously, which are very sensitive to the flow rate and water cut. The formation mechanism of the two kinds of differential pressure is analyzed theoretically, and their relationship with flow rate and water cut is studied by experiment and numerical simulation. The measurement model of heavy oil–water two-phase flow on the above relations is validated by field experiments. The radial differential pressure is only related to the two-phase flow rate, varying exponentially with the flow rate when the oil viscosity is greater than 10 000 mPa s. This characteristic is very useful for the heavy oil–water two-phase flow measurement. The axial differential pressure decreases with the increase in water cut in cases of water cut <85%, while it increases with the water cut in cases of water cut >85%. With the increase in water cut, the ratio of axial differential pressure to radial differential pressure first decreases and then increases. The relative errors of the established measurement model for flow rate and water cut are 0.19%–17.92% and 0.21%–15.5%, respectively, and more than 70% of the measurements with a relative error of less than 10%. The study of the heavy oil–water two-phase flow measurement method can optimize the measurement cost and accelerate the process of intelligent oilfield construction.

Effect of flow patterns and velocity field on oil-water two-phase flow rate in horizontal wells

In a wellbore, any change in flow rate will result in a change in flow pattern and velocity. The flow pattern and velocity are the key parameters that determine the pressure gradient and liquid holdup. To study the effect of the flow pattern and velocity field on the flow rate of oil-water flow in horizontal wells, we apply the commercial software package ANSYS Fluent 2020 R2 to predict the flow patterns, water holdups, pressure gradients, flow rates, and velocity fields of horizontal wells. Trallero’s flow pattern chart and existing experimental data are used to verify the reliability of the model. We develop a simplified mathematical model of water holdup and compare it with existing models. This mathematical model may be limited to the range of fluid properties in the simulated method. The water holdup of the numerical simulation has a definite correlation with the experimental data. By comparing the numerical simulation results of the Nicolas model, the relationship between the slip velocity and water holdup is verified, and the reliability of the simulation results is verified. The simulation results demonstrate that the change in flow pattern is highly sensitive to the change in flow rate. When the flow pattern is stratified flow, the relative error of the simulated flow is small. When the flow pattern is dispersed flow, the relative error of the simulated flow is slightly larger. The oil is mainly concentrated in the high-velocity core area. At a higher total mixing velocity, the flow pattern is that of dispersed flow, with one phase uniformly mixed in the other phase. The simulation results have good qualitative and quantitative agreement with the experimental results.

Measurement method of wet gas two-phase flow rate based on the main frequency and the modulus of vector acceleration of swirl flowmeter

The swirl flowmeter is widely used in the wellhead measurement of low-permeability gas fields in China. In this study, the MEMS three-axis acceleration sensor (MEMS-TAAS) replaced the traditional piezoelectric sensor to distinguish the frequency signal from the interference noise. Based on the MEMS-TAAS, the vector acceleration signals of swirl flowmeter were acquired and analyzed simultaneously with the precession frequency signals to establish a wet gas two-phase flow measurement model. The method of establishing a liquid volume fraction prediction model based on the vector acceleration modulus parameter was pioneered. Finally, a dual-parameter wet gas measuring method under normal pressure was constructed using an iteration algorithm. The results demonstrate that this model’s relative errors are acceptable. This method effectively provides further development thought for swirl flowmeter which can achieve the accurate prediction of two-phase flow using only one swirl meter with a MEMS-TAAS, without the need for other flow meters or differential pressure sensors, especially for the low-liquid-fraction wet gas.

A Model Based on the Random Forest Algorithm That Predicts the Total Oil–Water Two-Phase Flow Rate in Horizontal Shale Oil Wells

Due to variables like wellbore deviation variation and flow rate, the local flow velocity in the output wellbore of horizontal shale oil wells varied significantly at various points in the wellbore cross-section, making it challenging to calculate the total single-layer production with accuracy. The oil–water two-phase flow rate calculation techniques for horizontal wells developed based on particular flow patterns and array spinners had excellent applicability in their respective niches but suffered from poor generalizability and demanding experience levels for logging interpreters. In this study, we employed five spinners in a triangular walled array instrument to create the multi-decision tree after figuring out how many leaf nodes there were and examining the defining characteristics of the observed values gathered under various experimental setups. The construction of the entire oil–water two-phase flow prediction model was made possible when the random forest regression approach was used with it. The total oil–water flow rate at each perforated layer was predicted using the model in sample wells, and the mean square error with the third party’s interpretation conclusion was 1.42, indicating that the model had an excellent application effect. The approach, which offered a new interpretation method for calculating the oil–water two-phase flow rate of horizontal wells based on multi-location local flow rate, required less interpretation knowledge from the interpreter and had a stronger generalization capacity.

Two-Phase Flow Measuring with Ultrasonic Tomography

The exact measurement of multiphase flow is an important and essential task in the oil and petrochemical related industries. Several methods have already been proposed in this field. In the existing methods, flow rate measurement depends on the fluid flow pattern. Flow pattern recognition requiring calibration has created instability in such systems. In this paper, a imple and reliable method is proposed which is based on ultrasonic tomography. It is free from calibration and instability problems that existing methods have. The obtained data from a 32-digit array of ultrasonic sensors have been used and the two-phase flow rate including liquid and gas phases have been calculated through a simple algebraic algorithm. Simulation results show that while applying this method the measurement technique is independent from the fluid flow pattern and the system error is decreased. For the proposed algorithm, the average amount of the spatial imaging error (SIE) for a bubble at different positions inside the pipe is about 5%.

Mechanism of nanoparticle aggregation in gas-liquid microfluidic mixing

Using gas-liquid segmented micromixers to prepare nanoparticles that have a homogeneous particle size, controllable shape, and monodispersity advantages. Although nanoparticle aggregation within a microfluid has been shown to be affected by the shear effect, the shear effect triggering conditions in gas-liquid two-phase flow is unclear and the aggregation behavior of nanoparticles under the shear effect is difficult to predict, resulting in uncontrollable physical and chemical properties of nanoparticle aggregates. In this study, a numerical simulation of nanoparticle aggregation in gas-liquid two-phase flow under the shear effect is performed using the CFD-DEM method. Then, the effects of total flow rate, gas-liquid two-phase flow ratio, and particle volume fraction on particle aggregation were analyzed to achieve control of particle aggregation shape and size. Meanwhile, the triggering mechanism of the shear effect and the mechanism of the shear effect on the aggregation of nanoparticles were clarified. The results show that increasing the total flow rate or decreasing the gas-liquid two-phase flow rate ratio can induce the shear effect, which reduces the particle aggregation size and makes the morphology tend to be spherical. Moreover, increasing the particle volume fraction, and total flow rate or decreasing the gas-liquid two-phase flow rate ratio also increases the number of particle collisions and induce interparticle adhesion. Hence, particle adhesion and the shear effect compete with each other and together affect particle aggregation.

Generation of droplets of shear-thinning non-Newtonian fluids in T-junction parallelized microchannels

The study of shear-thinning non-Newtonian fluids in T-junction parallelized microchannels provides valuable insights into the emulsification process and droplet generation synchronicity. Silicone oil is used as the continuous phase, and sodium carboxymethyl cellulose (CMC) aqueous solutions are used as the dispersed phase. Based on the evolution of the dispersed phase head and neck characteristic size, the droplet generation is classified into four stages: the waiting stage, filling stage, necking stage, and pinch-off stage. The effects of the two-phase flow rates and rheological characteristics of shear-thinning fluids on the four stages are investigated. Additionally, the coupling of interface evolution between parallelized microchannels is studied, revealing periodic changes between synchronous and asynchronous droplet generation types. The impact of this phenomenon on droplet monodispersity is analyzed, providing crucial information for the preparation of uniform droplets.

Gas-liquid two-phase flow rates measurement using physics-guided deep learning

Machine learning has been widely used in the gas-liquid two-phase flow field. However, data-driven machine learning methods are often considered black-box methods which may lead to insufficient interpretation and extrapolation abilities. Combining machine learning and physical principles is a promising method to improve the generalization abilities and interpretation of the deep neural network model, which is still a challenge in gas-liquid two-phase flowrates measurement. In this work, we propose a physics-guided deep learning model for gas-liquid two-phase flow rate measurement through the differential pressure meter. The simplified physical constraint term of gas-liquid two-phase flow is established based on the momentum equation and continuity equation of gas-liquid two-phase flow, and then, the physical constraint term is added to the loss function of the deep neural network. Consequently, the predictions of the model not only satisfy the target values but also conform to the physical term. The performance of the physics-guided neural network (PGNN) is tested and compared with an artificial neural network (ANN) model that is trained without the physical constraint term. Results show that the gas and liquid flow rates could be measured simultaneously with satisfactory accuracy using the proposed PGNN model, more importantly, the model also performs well on a wider range of testing conditions (Gas Volume Fraction, GVF>95%). It indicates that this method is possible to improve the generalization and interpretation of the purely data-driven neural network model.

Study on effect of gas-liquid two phase physical feature on slug flow in microchannels

At present, there are relatively few studies on the slug flow generation mode obtained by exchanging gas-liquid two-phase inlets. In this study, an experimental system combining microfluidic devices and high-speed cameras was used to study the effects of gas-liquid two-phase flow rate, liquid physical parameters, etc., On the characteristic length, generation period and other generation characteristics of slug flow, and dimensionless analysis was conducted to investigate the main factors affecting the characteristic length of gas slug. Results show that 1) when the gas flow rate affects the aeroelastic generation characteristics, the aeroelastic characteristic length increases from 443 μm when the gas flow rate increases changes to 657 μm. The generation period decreases rapidly at first and then the change amplitude slows down. The maximum value of aeroelastic generation frequency is 217 s-1; 2) when studying the effect of different liquid flow rates, increasing the liquid flow rate, the characteristic length of the gas bomb gradually decreases, and the generation period of the gas bomb gradually increases. Aeroelastic characteristic length from 770 μm changes to 378 μm. The range of aeroelastic generation cycle is 4–13.4 ms, and the maximum value of aeroelastic generation frequency is 250 s-1; 3) there is a functional relationship between the ratio of aeroelastic characteristic length to channel size L/d and dimensionless gas-liquid flow ratio Q*, Reynolds number Re, Weber number We: L/d=3.677Q*0.58/Re0.11.

Droplet generation in a co-flowing microchannel influenced by magnetic fields applied in parallel and perpendicular to flow directions

In this study, ferrofluid droplet generation in a co-flowing microchannel is numerically studied in the presence of a uniform magnetic field, exerted parallel or perpendicular to the flow direction. The effects of field direction and parameters like the magnetic Bond number and two-phase flow rate ratio on the droplet breakup formation characteristics are investigated. Depending on the field direction, different responses of the system to alterations in the mentioned parameters are observed. By increasing the magnetic Bond number, droplet dimensionless diameter and dimensionless velocity increases for the parallel magnetic field and decreased by 5.15% and 36.91% for the vertical field, respectively. Implementing the perpendicular field, the droplet formation properties become insensitive to the magnetic Bond number at values more than 4.24 due to the transformation of the flow pattern from dripping to the slug flow regime. By increasing the two-phase flow rate ratio, the dimensionless diameter of the droplets decreases while their dimensionless velocity increases.

Two-phase mass flow rate through restrictions in liquid-flooded twin-screw compressors or expanders

Liquid flooded twin-screw machines are commonly used as compressors for different applications and offer excellent prospects for energy conversion in lower and medium power ranges as expansion engines in Rankine cycles for example with regard to either waste heat recovery or electrical power generation from regenerative heat sources. With the aim of minimising internal leakages, lubricating moving machine parts, or reducing thermal stress and providing the benefits of wet expansion, a twin-screw machine can be operated with an auxiliary liquid or a two-phase working fluid. In this context, the present work provides a basic approach addressing the two-phase mass flow rate calculation in water-flooded twin-screw machines. Based on a generic inlet-geometry model, two-phase mass flow rates are recorded for different operating conditions and mass dryness fractions in particular. Appropriate approaches for the theoretical two-phase mass flow rate and discharge coefficient calculation considering restrictions in the flow section—such as orifices and nozzles—are applied. Finally, the two-phase discharge coefficients are compared with flow coefficients determined by means of experimental and theoretical two-phase mass flow rates revealing the limits and uncertainties of the models applied in this study.

Microdispersion of Gas or Water in an Anthraquinone Working Solution for the H2O2 Synthesis Process Intensification

The Reidl–Pfleiderer process intensification for H2O2 synthesis is urgently required. Microdispersion technique is becoming one of the highest promising ways, but the microdispersion rules of gas or liquid in the anthraquinone working solution have not been mentioned until now. This study employs an observation platform to investigate the microdispersion performances of hydrogen, oxygen, or water in the anthraquinone working solution to provide reliable data for developing new microchemical processes. The influence of two-phase flow rate, viscosity, and channel size on bubble size in a circular microchannel was studied. A specific surface area higher than 20 000 m2/m3 was obtained when the channel size was 150 μm. A unified mathematical prediction model for the gas–liquid and liquid–liquid microdispersion was developed, and it can be used for the future practical industrial system process intensification.

Numerical study on the hydrodynamics behavior of a central insert microchannel

• A modified 3D model was used to simulate the formation of flow patterns in MC1 and MC2. • The flow pattern graphs captured by the camera agree well with the simulation. • The unique bicontinuous flow patterns in MC2 were obtained and studied. • The size laws of flow patterns in MC1 and MC2 were presented. In this work, the computational fluid dynamics method is used to study the liquid hydrodynamics behavior in the microchannel without central insert (MC1) and the central insert microchannel (MC2), respectively. The maximum deviation between simulation and experiment is 24%. The formations of flow patterns are explained based on contours and force analysis where the flow pattern maps are established by two-phase flow rate. The effects of aqueous phase viscosity and two-phase flow rate on the characteristic sizes of each flow pattern are also explored. Specifically, four unconventional flow patterns are found in MC2, namely the unique droplet flow, the unique slug flow, the unique coarse annular flow and the unique film annular flow. Though the insert occupies part of the channel, the pressure difference in the channel is significantly reduced compared with MC1. Moreover, the insert significantly changes the formation velocity range of each flow pattern, greatly broadens the formation range of annular flow and also has an important influence on the characteristic size of the flow pattern. The organic-phase dimensionless axial size ( L o / W ) and the dimensionless radial size ( D o / W ) of the droplet (slug) are negatively related to the aqueous-phase viscosity ( μ a ) and flow rate ( u a ). The D o / W of the annular is negatively correlated with μ a and positively correlated with organic-phase flow rate ( u o ). This study provides direct numerical evidence that the insert is key to the formation of bicontinuous phase flow pattern, as well as further strengthens our understanding of the flow characteristics and optimization design of insert microchannels.