Differential Pressure Flow Research Articles

Calibration modeling of drilling fluid rheological parameters in variable temperature environment based on support vector machine.

Traditional measurement of drilling fluid rheological parameters suffers from significant lag due to the inability of the instruments to promptly capture real-time parameters of the drilling fluid. These measurement models are typically constructed based on fixed temperature conditions and empirical formulas, rendering them inadequate for complex temperature gradient environments. Consequently, this limitation results in increased prediction errors, severely compromising the precise monitoring of drilling fluid performance. Aiming at the problems of low accuracy and poor stability of drilling fluid measurements under variable temperature conditions, a support vector machine-based calibration model for drilling fluid rheological parameters in a variable temperature environment is proposed in this paper. First, the measurement principle of the double-tube differential pressure rheology real-time measurement device is analyzed. The relationship between shear stress and shear rate is then established using differential pressure sensor and flow rate data. Utilizing the gray wolf optimization algorithm to optimize the kernel function weights and parameters, an SVM-based calibration model for predicting drilling fluid rheology correction parameters is constructed. Finally, a real-time monitoring platform for drilling fluid is developed. Experimental results show that the maximum relative errors for the predictions of apparent viscosity, plastic viscosity, and yield point are within ±5%, with coefficients of determination (R2) all greater than 0.95. These results validate the effectiveness of the proposed method in accurately monitoring the rheological performance of drilling fluids.

Calibration of flow differential pressure coefficients on pump-turbine by thermodynamic method

On-line monitoring of flow rate is rather important to evaluate the water consumption of the pump-turbine and the overall efficiency of the pumped storage station. Flow rate can be worked out based on the flow differential pressure measured in the flow passage and coefficients determined on model test. But the coefficients must be calibrated to obtain the reliable flow rate. As thermodynamic method is a common way to measure the discharge of prototype pump-turbine, site test is carried out on a vertical pump-turbine with 600 m rated head to calibrated the coefficients in this paper. Measuring devices are designed to satisfy both the turbine and pump operating conditions, and test results of flow rate at both turbine and pump operating conditions are presented and show that the calibrated coefficients are different to the predicted values. The calibrated results indicate the importance of site calibration on prototype turbine to ensure the monitoring validity on real-time flow rate.

Flow regimes identification of air water counter current flow in vertical annulus using differential pressure signals and machine learning

This study investigates the gas–liquid two-phase counter-current flow through a vertical annulus, a phenomenon prevalent across numerous industrial fields. The presence of an inner pipe and varying degrees of eccentricity between the inner and outer pipes often blur the clear demarcation of flow regime boundaries. To address this, we designed a vertical annulus with adjustable eccentricity (outer and inner diameters of 125 mm and 75 mm, respectively). We conducted gas–liquid counter-current flow experiments under specific conditions: gas superficial velocity ranging from 0.06 to 5.04 m/s, liquid superficial velocity from 0.01 to 0.25 m/s, and five levels of eccentricity (e = 0, 0.25, 0.5, 0.75, 1). We collected differential pressure data at two distinct height distances (DP1: 50 mm and DP2: 1000 mm). We used vectors, composed of both the probability density functions (PDFs) of the differential pressure signals and the power spectral density (PSD) reduced via Principal Component Analysis, as features. Using the CFDP clustering algorithm—based on local density—we clustered the flow regimes of the experimental data, thereby achieving an objective and consistent identification of the flow regime of gas–liquid two-phase counter-current flow in a vertical annulus. Our analysis reveals that for DP1, the main differences in the PSD of various flow regimes occur within the 0.5–1 Hz range. Among the three flow regimes involved, the slug flow exhibits the highest power intensity, followed by the bubbly flow, with the churn flow having the least. In terms of differential pressure distribution, the bubbly and churn flows have a concentrated distribution, while the slug flow is more dispersed. For DP2, the PSD differences primarily exist within the 0.5–2 Hz range. The churn flow has the highest power intensity, followed by the slug flow, with the bubbly flow being the weakest. Here, the bubbly flow's differential pressure distribution is concentrated, while the slug and churn flows are more dispersed. Based on the results of the flow regime classification, we generated a flow regime map and analyzed the influence of annulus eccentricity on the flow regime. We found that in most cases, pipe eccentricity does not significantly affect the flow regime. However, in the transition region—such as the bubbly to slug flow transition zone—flows with medium eccentricity values (e = 0.5, 0.75) are more likely to transition to slug flow. We compared the visual recognition results of flow regimes with the clustering results. 4.04% of the total samples showed different results from visual recognition and clustering, primarily located in the flow regime transition area. Since visually distinguishing flow regimes in these areas is typically challenging, our methodology offers an objective classification approach for gas–liquid two-phase counter-current flow in a vertical annulus.

Development of a Measurement Device for Micro Gas Flowrate Based on Laminar Flow Element with Micro-Curved Surface

The laminar flow meter (LFM) boasts several advantages such as no moving parts, a wide range ratio, high measurement accuracy, quick dynamic response, etc., and is a promising technology for micro gas flow measurement. In order to explore the influence of different curvature radii on curved surface gap LFM, three curved structures with different curvature radii were designed. The computational fluid dynamics method is applied to simulate the flow feature of three structures. The simulated velocity cloud and pressure distribution show that the larger the curvature radius, the more stable the flow of gas medium. The relationship between differential pressure and volume flow was obtained through the test within a flow range of 0~540 sccm. Regression analysis revealed that the volume flow measured by the curved surface LFM had a high linear relationship with the differential pressure. Experimental findings indicate that differential pressure of the structure with a curvature radius of 2 mm was greater than that of other two structures (curvature radius of 6 mm and 3 mm) at the same point. This indicates that adding the number of surfaces can effectively increase the pressure loss, so as to obtain a larger range ratio, but will increase the measurement error.

Multivariate coupled full-case physical model of large chilled water systems and its application

Chilled water systems in large-scale central air conditioning consume more than 30 % of the total energy. To reduce this energy consumption, a model can be used to explore the optimal operating parameters of chilled water systems. The chilled water system is a multivariable highly coupled nonlinear system. The type and number of variables change with the hydraulic characteristics of the piping network and the operating data sparsity is high. For these reasons, data-driven methods are not suitable for modeling chilled water systems. Therefore, there is an urgent need to develop a model that is not constrained by the type and number of variables and can establish a complete data structure. According to the principles of differential pressure equilibrium, flow conservation, and thermal equilibrium, this study establishes a physical model of the hydraulic–thermal coupling of chilled water systems. The hydraulic–thermal characteristics of chilled water systems under multiple operating conditions were investigated, and the reliability of the model was verified through experiments. Furthermore, the difficulty of effective modeling owing to dynamic changes in the types of variables and lack of operating data were addressed. The study showed that the model has a wide range of applications, high reliability, and high computational efficiency.

Characterization of multiphase flow through Venturi nozzle using gamma-ray tomography

Venturi-based differential pressure flow meters have proven to be robust and well suited to measure the flowrate of multiphase flow in combination with other measurement techniques. However, important challenges remain in order to reduce the effect of flow regime dependent measurement uncertainties from non-homogeneous flow.Understanding the complexities of multiphase flow through a Venturi is critical, not only for the Venturi flow measurement but also for the potential implications it might have on adjacent measurements affected by the constriction-induced flow perturbations.In this study, we examine the evolution of multiphase flow through a vertically oriented Venturi situated downstream of a T-bend, with a particular emphasis on the effects this might have on associated measurements within a multiphase metering context. Using Gamma-ray tomography, we conducted measurements at the inlet, throat, outlet, and downstream of the Venturi across a wide range of flow rates and Gas Volume Fractions (GVFs). We evaluated gas fraction (GF), slip, and cross-sectional distribution, quantified using measures of asymmetry and annularity.Our findings suggest that deviations between GF and GVF, relative slip velocity, annularity, and asymmetry are generally less at the outlet and downstream of the Venturi compared to the inlet and throat. Notably, annularity exhibits a greater impact than asymmetry on the estimation of bulk fractions from cord measurements.Overall, the study suggests that there may be more favorable conditions for measurements that require a homogeneous mix and less difference between GF and GVF at the outlet or a short distance downstream of the Venturi. However, despite the inlet results showing larger deviations due to inhomogeneous flow compared to the outlet and downstream, these results demonstrate a more predictable pattern in line with predictive models, offering potential benefits for the application of corrective models.

Research on the Error Calibration Method of Rheological Parameters of Rectangular Tubular Viscometer

In order to solve the problem of high error in the process of measuring the rheology of drilling fluids by the common pipe flow method, an online measurement device for the rheology of drilling fluids with rectangular tubular drilling fluids was fabricated, and a calibration method for the measurement error of rheological parameters was proposed and corresponding experiments were carried out. By measuring the differential pressure value and flow, flow rate and other parameters when the drilling fluid flows through the measuring tube, upload them to the host computer for processing, use VMD to decompose the measured differential pressure data, remove the residual term, and then perform Hibert transform on each modal component to obtain its analytical signal, modulate the amplitude and phase of each analytical signal, and then reconstruct the signal to obtain the optimized differential data, and finally bring it into the constructed calibration model of the rheological parameter measurement error of drilling fluid to obtain the rheological parameters. The experimental results show that the proposed method can obtain more accurate rheological parameters of drilling fluid, improve the measurement accuracy of drilling fluid rheology parameters, so as to judge the downhole situation more accurately and ensure the personal safety of on-site staff.

Insights into unique in-situ self-adaptive sealing property of pressure-activated sealant in leaks: Experimental and numerical investigations on mechanism of liquid-to-solid transformation triggered by differential pressure

Pressure activated sealant (PAS) has been proven safety and efficiency for quick leak repairs in oil & gas production, due to the unique in-situ self-adaptive sealing property. However, its sealing mechanim of the liquid-to-solid transformation under leak pressures remains poorly understood to date. Elucidating the sealing mechanism of PAS is critical for designing and developing a new generation of wellbore sealing repair technology. In the present work, we conducted a pioneering investigtion that integrated experimental techniques with numerical simulations, to systematically explore the in-situ self-adaptive sealing performance of PAS in leaks. Firstly, latex deposition experiments were carried out to fabricate PAS from carboxylated acrylonitrile butadiene rubber latex (XNBRL), and then the physicochemical features of the XNBRL-based PAS, including chemical composition and microsctructure, were typically characterized using FTIR and SEM techniques. Subsequently, the micro-leak sealing capability of XNBRL-based PAS was evaluated under 20 MPa. The results showed that the fabriacted PAS is a type of multiphase fluid, wherein disperse phase are of regular spherical shape with an average size of 239.75 μm. The disperse phase are essentially compound droplets with material interfaces, exhibiting unique interfacial mechnical and chemical properties in the surrounding flow. PAS demonstrated excellent pressure-activated sealing performance towards crack and screw leaks, and solid barriers can be rapidly formed to fill micro-leaks in 500s under 16 MPa. Considering the microstructural and dynamic features of compound droplets, a mechanical-chemical coupling model was proposed to explain the activation and agglomeration process of liquid sealant at leak. In the jet flow field caused by differential pressures, the self-adaptive sealing process of PAS consists of four stages: (1) the impact deformation of compound droplets in jet flow, (2) compound droplets activated by breakup of hydrated membrane, (3) adhesion and agglomeration of activated compound droplets, and (4) self-adaptive solidification of deformed drolpets to fill and block leakages. Finally, three-dimensional (3D) numerical simulations were empolyed to investigate dynamic deformation of compound droplet in the pressure differential flow, to rationalize liquid-to-solid transformation of PAS. The numerical results showed that dynamic motion of compound droplet in jet flow field includes deformation of compound droplet, breakup of outer hydrated membrane, and collision of inner polymer core with wall. The hydrated membrane completely breaks up into ligaments in 0.8 ms, facilitating exposure of activated inner core and enables further chemical agglomeration, which agrees generally well with the experimental and model analyses.

Effects of Turbulence‐Induced Blade Position on Flow and Combustion in a Wankel Rotary Engine

Aiming at the problem of low turbulent velocity and incomplete combustion in the combustion process of the Wankel rotary engine (WRE), and setting turbulence‐induced blade (TIB) in the combustion chamber recess is an effective means to enhance the turbulent motion and promote combustion. Carifying the optimal arrangement position of TIB can get better combustion performance. Therefore, a computational fluid dynamics (CFD) simulation model of a WRE with TIB was established in this paper. Based on the differential pressure perturbation mechanism, the influence of the arrangement position of the TIB on the flow field and combustion performance were analyzed. The results showed that when the ratio of blade arrangement distance is less than 0.66, the pressure difference between the leading and trailing of the blade is small. At this time, the in‐cylinder flow is mainly disturbed by the forced disturbance of the TIB, the increase of the turbulent velocity is not obvious, and the diffusion velocity of the flame to the rotor direction is small. When the ratio of blade arrangement distance is greater than 0.66, the pressure difference between the leading and trailing of the blade is large. At this time, the In‐cylinder flow is affected by the pressure difference flow in addition to the forced disturbance of the TIB. The turbulent velocity is effectively enhanced, and the flame velocity is fast to the rotor direction. When the ratio of blade arrangement distance is 0.66, it shows the best combustion performance, and the indicated work is the largest. Compared to the scheme without TIB, the indicated work is increased by 16%.

A 3D numerical model for the performance analysis of a differential pressure flow meter in transient conditions for liquid fuels

In the present paper, the metrological performance of a single-hole, sharped edge, and the orifice flow meter is numerically investigated employing different liquid fuels. Numerical investigations have been performed for a three-dimensional transient flow. Turbulence has been modeled employing the Realizable K-ε turbulence model, based on the Unsteady Reynolds-averaged Navier-Stokes (URANS). The present work is conducted in the context of the European SAFEST 20IND13 project, aimed at investigating the performance of the orifice flow meter numerical model in a wide range of temperatures, density, viscosity, and different liquid fuels. The numerical model, validated according to the ISO standard 5167-2 is employed to analyze the metrological performance of a test rig available at project partners’ laboratories and was aimed at reproducing the fuel consumption curve of a light and heavy transport vehicle.

Fault detection, diagnosis and calibration of heating, ventilation and air conditioning sensors by combining principal component analysis and improved bayesian inference

Sensors are crucial components in heating, ventilation and air conditioning (HVAC) systems. When sensors fault, the HVAC system deviates from normal operation, resulting in an increase in energy consumption and a decline in equipment lifespan. Therefore, it is vital to detect, diagnose and calibrate the sensor faults. Bayesian Inference (BI) in data-driven methods is highly effective for sensor calibration. However, its application faces two major shortcomings. First, the conventional BI method cannot effectively calibrate sensor drift faults. Second, the BI method relies on sensor fault detection and diagnosis (FDD). To address these shortcomings, this study proposed an improved BI (imBI) method that enhanced the capability of BI to calibrate drift faults by updating the calibration constant x. Moreover, sensor fault detection, diagnosis and calibration (FDDC) were conducted by combining Principal Component Analysis (PCA) with the imBI method (PCA-imBI). The proposed methods were validated through two case studies involving a chiller system and an air handling unit (AHU) system, having different degrees of bias faults and drift faults in temperature sensors, differential pressure sensors and flow sensors. The results demonstrated that the PCA-imBI method effectively achieved FDDC for both bias and drift faults. Considering the case studies, the average calibration rates for bias and drift faults reached 99.74 % and 95.29 %, respectively. For drift fault calibration, the imBI method outperformed the dynamic calibration method and PCA reconstruction method by 16.04 % and 4.31 %, respectively.

Construction and application of flow pressure drop model of perforated well considering pressure loss of perforation hole

Perforating well is one of the main production wells in reservoir development. Perforating effect directly affects well production, so the optimization of perforating parameters has attracted wide attention. Because pressure difference serves as the driving force for fluid flowing from formation to wellbore, it is important to understand the composition of production pressure difference in perforating well, which can guide the optimization of perforating parameters and the evaluation of perforating effect. In order to clarify the composition of production pressure difference during the production process of perforated wells, a pressure drop model pressure drop model is established based on fluid mechanics theory, which includes a pressure drop model of formation and a pressure drop model of perforation hole. The pressure drop model of formation is firstly constructed based on the Darcy's law and the equivalent resistance method, and the pressure drop model of perforation hole is built by the fluid tube-flow theory. Secondly, the numerical calculation method is adopted to realize the coupling solution of models, and the accuracy of this model is verified by comparison of the Karakas-Tariq model. Finally, the effects of formation physical properties and perforating parameters on flow pressure drop are discussed. The results show that there is a difference of more than 2 orders of magnitude between the pressure drop generated in perforation hole and flow pressure difference, and pressure drop of perforation hole can be neglected in practical applications. Comparing with medium–high permeability reservoirs, optimizing perforation parameters in low permeability reservoirs has a more significant impact on flow pressure drop. Among perforating parameters, perforation length and perforation density have great influence on flow pressure difference, while perforation diameter and phase angle have relatively little influence. These results have certain guiding significance for optimizing perforating parameters in different permeability reservoirs.

Study on a differential pressure microflow sensor on microfluidic chip

Based on the principle of differential pressure flow measurement, graphene film was used to measure the differential pressure in the micro channel of microfluidic chip and finally to obtain the micro flow rates. The relationship between differential pressure and flow rate in micro channel was studied and validated by CFD simulation. The fiber F-P cavity using graphene film was fabricated as the pressure sensitive structure, and the relationship between the measured pressure and the optical power output from the pressure sensitive structures was studied. The mechanism model used to measure the micro flow rates in the micro channel of microfluidic chip was established, and a sample of micro flow sensor was fabricated. The relationship between various quantities in the process of converting flow rate to optical power was verified through experiments, and the mechanism model established was verified. The experimental results demonstrate that fabricated sample could achieve accurate measurement of micro flow rate in the micro channel of microfluidic chip.

Energy-Saving Testing System for a Coal Mine Emulsion Pump Using the Pressure Differential Flow Characteristics of Digital Relief Valves

Most energy-saving testing methods for plunger pumps use hydraulic motors. The loading test of coal mine emulsion pumps generally uses an overflow valve as the loading unit, which is characterized by high energy consumption. The coal mine emulsion pump uses emulsion as the transmission medium, and the viscosity and lubricity of the emulsion are much lower than those of hydraulic oil, which creates great difficulties in the development of high water-based hydraulic products. The nominal flow rate of the emulsion motor is much smaller than that of the emulsion pump, and there is no mature and reliable water-based flow control valve. Based on the above reasons, traditional energy-saving testing methods cannot be utilized for the testing process of emulsion pumps. The loading test of emulsion pumps generally uses an overflow valve as the loading unit, and during the testing process, all electrical energy is converted into internal energy, resulting in very high energy consumption. This article proposes an energy-saving testing system for emulsion pumps based on multiple emulsion motors in parallel. In order to solve the flow regulation problem of each parallel branch, a flow-intelligent control algorithm is proposed that utilizes the pressure difference flow characteristics of digital relief valves combined with artificial neural network predictive control. Firstly, the feasibility of the proposed system and method is theoretically verified through the analysis of the mathematical model of the digital relief valve. Secondly, further verification is carried out by establishing simulation and testing platforms. The simulation results show that the energy recovery efficiency of the system exceeds 53%. The experimental results show that the proposed testing system has a pressure control error of less than 1%, a flow control error of about 5%, and a maximum overshoot of about 9 L/min relative to the steady-state flow rate. The control accuracy and system stability are high.

Characterization of Flow Parameters in Shale Nano-Porous Media Using Pore Network Model: A Field Example from Shale Oil Reservoir in Songliao Basin, China

The pore-throat radius of the shale oil reservoir is extremely small, and it is difficult to accurately obtain the absolute permeability and oil–water two-phase relative permeability of the actual oil reservoir through conventional core experiments. However, these parameters are very important for reservoir numerical simulation. In this paper, a method for characterizing flow parameters based on a pore network model that considers differential pressure flow and diffusion flow is proposed. Firstly, a digital core was reconstructed using focused ion beam scanning electron microscopy (FIB-SEM) from the Gulong shale reservoir in the Songliao Basin, China, and a pore network model was extracted. Secondly, quasi-static single-phase flow and two-phase flow equations considering diffusion were established in the pore network model. Finally, pore-throat parameters, absolute permeability, and oil–water two-phase permeability curves were calculated, respectively. The results show that the pore-throat distribution of the Gulong shale reservoir is mainly concentrated in the nanometer scale; the mean pore radius is 87 nm, the mean throat radius is 41 nm, and the mean coordination number is 3.97. The calculated permeability considering diffusion is 0.000124 mD, which is approximately twice the permeability calculated without considering diffusion. The irreducible water saturation of the Gulong shale reservoir is approximately 0.4, and the residual oil saturation is approximately 0.35. The method proposed in this paper can provide an important approach for characterizing the flow parameters of similar shale oil reservoirs.

Study on the calibration and uncertainty evaluation of direct-reading atmospheric samplers by laminar flow differential pressure mass flowmeter

Air sampler is an important measuring instrument for environmental monitoring. With the rapid development of environmental protection industry, the direct reading air sampler has been widely used and this is also related to the improved develop rate of new products. As it only aims at the situation that the standard meter is soap film flowmeter and the measured meter is rotor air sampler, the JJG 956-2013 metrological verification regulation for air sampler is not applicable to the direct reading air sampler. Meanwhile, the corresponding standard meters are also developing rapidly and more results showed that the laminar differential pressure mass flowmeter has more advantages than the soap film flowmeter in the regulation. It can not only improve calibration efficiency, but also realize automatic calibration or remote calibration. In this paper, the method of calibrating direct reading air sampler by laminar flow differential pressure mass flowmeter is studied. The mathematical model of flow rate and relative indication error used in the calibration condition is proposed, and the uncertainty of indication error is also analyzed in detail. In addition, the evaluation example is given accordingly, which fills the blank in the regulation.

Development of a novel two-dimensional(2D) three-way(3W) fuel flow control servo valve with constant pressure difference

To solve the problems of large volume, and low integration of traditional electro-hydraulic servo valve with constant pressure differential fuel metering device, a new two-dimensional three-way constant pressure differential fuel flow control servo valve (2D3WFFCSV) is developed. It innovatively adopts the advantages of lightweight of “two-dimensional hydraulic technology”, The constant differential pressure function and flow regulation function are integrated into a two-dimensional (2D) main spool with two degrees of freedom (rotational and axial degrees of freedom). The flow control process of 2D3WFFCSV is as follows: firstly, the armature of the torque motor and the two-dimensional piston are coaxially installed at the end of the two-dimensional piston, so the torque motor can directly drive the two-dimensional piston to rotate; secondly the “hydraulic servo screw mechanism”, which can amplify the power, is used to drive the two-dimensional piston to move in line; Finally, a pair of conversion mechanisms (roller group and spiral track conversion mechanism) are converted into the angular displacement of 2D main spool to control the area of flow valve port. The axial degree of freedom of 2D main spool realizes the function of constant differential pressure. To improve the flow control accuracy of the servo valve, the axial position of the 2D piston is detected by the linear displacement sensor (LVDT), and the signal is transmitted to the controller to realize the closed-loop control. To explore its open-loop characteristics, the mathematical models of torque motor, two-dimensional piston and main spool are established to obtain its open-loop transfer function. Then the AMESIM simulation model is built. To optimize the design of the system, through the dynamic simulation of the system, the influence of key parameters on the dynamic response of the system can be studied. An experimental study is carried out to verify the design feasibility of the servo valve. The experimental results show that under the condition of no-load and full-scale input, the closed-loop delay of the servo valve is 1.84%, the linearity is 2.14%, the step response time is 43 ms, and the dynamic frequency response is 38 Hz. The newly developed 2D3WFFCSV has the advantages of high integration, small size, light weight (801.5 g) and high response and control accuracy. It can replace the constant differential pressure, metering valve and hydraulic servo valve in the aeroengine fuel regulator.

Численное моделирование аэродинамических процессов движения воздушных масс в тоннелях метрополитена с учетом «поршневого» воздействия подвижного состава

Purpose: To consider the issue on verification of numerical model of air exchange during the movement of a train in a subway tunnel, taking into account the process of interaction of regular ventilation with the piston effect of the displaced air by the body of the moving train. Methods: Data scanning and processing. The equipment used was a pressure cylindrical Pitot tube PFM 2 for measuring differential pressure and air flow velocity, volumetric flow and temperature. Results: The dynamic structure of disturbed fluid media at the time of rolling stock arrival and departure has been established. Practical importance: Factors of design solutions of tunnel portal part affecting the process of air exchange at the combined work of ventilation and piston effect of moving trains have been determined.

Methods for gas permeability measurement in edible films for fruits and vegetables: a review

Permeability is a crucial parameter to describe the transport rate of a gas under pressure gradient, relevant to gas molecule movement in pores. The gas permeability of edible film, used on fresh or minimally processed fruits and vegetables, is an important parameter because it directly affects the product’s respiration rate and metabolic activity. The present study summarizes the principal methods for gas permeability measurement in edible films, considering methods developed at laboratory scale and the methods of the American Society for Testing and Materials Standards (ASTM), some of which have been adapted for edible films. The methods are classified as follows: gravimetric, differential pressure, and continuous flow. Gas permeability results depend heavily on the procedure achieved and laboratory conditions employed, as well as the preconditioning of the films before the tests.

CFD study of the transient wet gas flow behavior through orifice plate flow meters

Differential pressure flow meters are widely used in wet gas flow measurement, typically, combined with a method to determine the liquid fraction. An alternative with significant advantages for industry, in term of cost, operation and maintenance, is determining the liquid fraction based on its relation with the statistical parameters of transient differential pressure signal fluctuations. In this way, a single measurement device can provide mass flow rate and liquid fraction simultaneously. For this method to be more feasible in the wet gas flow measurement, it is essential to understand how the differential pressure signal fluctuations and the gas–liquid flow behavior at the restriction are correlated. On this basis, this paper presents a transient 3D Computational Fluid Dynamics (CFD) study of the wet gas flow through an orifice plate, operating under field conditions, using the two-fluid model. Steady-state results, calculated from the time averaging of the transient solution, for the over-reading OR parameter were validated with experimental field data and results obtained by correlations available in the literature, showing very good agreement. The transient results from simulations presented a trend in agreement with experimental data from the literature, showing a positive correlation of the standard deviation of differential pressure signal with liquid fraction upstream of the orifice plate. However, these results should be analyzed qualitatively due to model limitations, mainly related to the interfacial transfer closure in gas–liquid flows with changing phase morphologies. Despite this fact, some important insights regarding the 3D transient flow structure with a practical value were obtained from the model.