Slotted Orifice Research Articles

Wet gas metering technique based on slotted orifice and swirlmeter in series

Wet gas flow is a subset of gas–liquid two-phase flow, and wet gas metering is gaining considerable attention due to its importance in the nuclear, oil and gas industry. Wet gas meter based on slotted orifice and swirlmeter combination in series was designed and investigated. A wet gas measurement model with the simultaneous equations from the two flowmeters' correlations has been established, and then an iterative solution algorithm is given. The novel proposed approach predicts the gas mass flow rate relative errors within ±6% from 89.2% tested samples, and the gas mass flow rate relative errors within ±20% from all tested samples, which is accepted for many wet gas applications. Therefore, it implies that the proposed wet gas metering technique may be used to meter both gas and liquid flow rates for wet gas flow at the Lockhart Martinelli parameter X≤0.12.

Study on discharge coefficient of perforated orifices as a new kind of flowmeter

A perforated orifice is promising in measuring flowrates accurately as a differential pressure device. In this study, the discharge coefficient of a perforated orifice, characterizing the relationship between the volumetric flowrate and the pressure drop across the orifice is presented. Different structures are tested experimentally including orifice thickness, porosity, hole distribution and upstream disturbance. For each case, a wide range of flowrate was tested in a horizontal single-phase water pipe with an I.D. of 29mm. For comparison, the discharge coefficient was also obtained for the corresponding standard orifice with the same porosity and thickness. Meanwhile, the effect on the discharge coefficients of the structural parameters was assessed in terms of pressure drop. The theoretical analysis shows that a perforated orifice yields a weaker distortion to the flow than the corresponding standard orifice, indicating a lower pressure drop and a more stable flow field for the former. The experimental results show that the discharge coefficient of a perforated orifice is 22.5–25.6% larger but with a weaker scattering than that of the corresponding standard orifice. Furthermore, a perforated orifice has a lower critical Reynolds number and a stronger anti-disturbance ability. As a flowmeter, the perforated orifice is comparable to the newly developed differential pressure orifices, e.g. V-cone and slotted orifices, but with a simpler structure.

Heat transfer characteristics of a pair of impinging synthetic jets: Effect of orifice spacing and impingement distance

Recent research has shown that an impinging synthetic jet attains local heat transfer rates that rival those of a steady impinging jet. A single synthetic jet still requires a buoyancy-driven or forced cross flow to avoid recirculation of heated fluid. However, multiple adjacent synthetic jets exhibit a fluidic interaction that results in flow vectoring towards the direction of the jet leading in phase. Previous results have shown a significant heat transfer enhancement and the establishment of a jet-induced cross-flow, which could eliminate the need for an external forced cross-flow. This paper presents the findings of an experimental study to optimize the orifice-to-impingement distance H and orifice centre-to-centre separation distance S. The convective heat transfer rate is determined on an electrically heated metal foil using thermal imaging. The jets are driven by a pair of adjacent jet actuators forcing air through two rectangular slot orifices of width D = 1.65mm and aspect ratio α = 27:1. The jets are maintained at a constant Reynolds number and stroke length (Re = 600, L0/D = 29). For the parameter range considered, an optimum setting of H/D = 24 and S/D = 3 operated within a phase difference region of 60° < ϕ < 120° gives the best cooling performance.

Wet Gas Flow Metering Based on Differential Pressure and BSS Techniques

Wet gas flow is a typical two-phase flow with low liquid fractions. As differential pressure signal contains rich information of flow parameters in two-phase flow metering, a new method is proposed for wet gas flow metering based on differential pressure (DP) and blind source separation (BSS) techniques. DP signals are from a couple of slotted orifices and the BSS method is based on time-frequency analysis. A good relationship between the liquid flow rate and the characteristic quantity of the separated signal is established, and a differential pressure correlation for slotted orifice is applied to calculate the gas flow rate. The calculation results are good with 90% relative errors less than ±10%. The results also show that BSS is an effective method to extract liquid flow rate from DP signals of wet gas flow, and to analysis different interactions among the total DP readings.

Wet Gas Measurement with Slotted Orifice Meter--Effect of Geometry of Slots and Pressure

Wet gas metering by differential pressure flow meters is gaining prominence in the oil and gas industry, owing to their simple construction. Slotted orifice, a modified version of the standard orifice meter has been found promising by many researchers. This novel flow meter is shown to be insensitive to the upstream flow profile with lower head loss and faster pressure recovery compared to the standard orifice. In the present work, the effect of geometry of slots and pressure on the performance of the slotted orifice has been studied by CFD modeling of the wet gas flow. The performance of slotted orifice with rectangular perforations (1.5 ≤ l/w ≤ 3.0) and circular perforations has been compared with that of the standard orifice having same β-ratio of 0.40. Simulation results reveal that the shape of perforation of the slotted orifice has no effect on the differential pressure. However, the pressure recovery with the rectangular slots is found to increase with increasing aspect ratio. Moreover, at low pressure, slotted orifice is found to be more sensitive to liquid presence than the standard orifice. The relatively higher over reading values obtained in this work is consistent with the results of Geng et al (2006) that for slotted orifice, a low beta ratio is more sensitive to the liquid presence in the stream and hence is preferable for wet gas metering. Homogeneous model, Steven’s and De Leeuw’s correlations, are found to be better than orifice correlations for wet gas mass flow prediction.

A CFD study of low pressure wet gas metering using slotted orifice meters

Wet gas metering is becoming an increasingly important problem to many industries, in particular the oil and gas industry. Extensive studies have been done in the past on Venturi and standard orifice differential pressure (DP) flow meters to tackle wet gas flow problems. However in recent years, the slotted orifice flow meter has been developed in the attempt to improve the performance of the standard orifice meter. The novel flow meter is shown to be insensitive to the upstream flow profile with lower head loss and faster pressure recovery. This paper describes the numerical studies to establish the effect of different geometrical perforations on the performance of the slotted orifice. Three sets of slotted orifices with varying aspect ratios ( 1.5 ≤ l / w ≤ 3.0 ), of rectangular perforations and one slotted orifice with a circular perforation and a β ratio of 0.40 are simulated in a 1.6 m horizontal pipe using the k – ε turbulence model over a range of parameters, i.e. gas volume fraction (GVF) and gas mass flow rate. The commercial CFD code, FLUENT 6.3 was used to model the wet gas flow. Simulation results revealed that the shape of the perforation has no effect on the differential pressure, However, a marginally better pressure recovery was observed with rectangular perforations of l / w = 3.0 . The relatively higher over-reading values obtained in this work are consistent with the results of Geng et al. (2006) [1] that for a slotted orifice, a low β ratio is more sensitive to the liquid presence in the stream and hence is preferable for wet gas metering. Mass flow prediction by wet gas correlations showed that the homogeneous model, Steven’s and De Leeuw’s correlations had the best performance, with a calculated mean error of 4%–5%.

Study on the dynamic characteristics of a new type externally pressurized spherical gas bearing with slot–orifice double restrictors

This study proposes a new type externally pressurized spherical gas bearing with slot–orifice double restricted restrictors, used in a new type gas gyroscope. Based on the spherical Reynolds equation and cylindrical Reynolds equation, small perturbation theory is employed to analyze the dynamic characteristics of the new type externally pressurized spherical gas bearing. The slot gas film and the spherical film are united by means of compatibility condition and a weak solution formula, based on Galerkin residual method, is erected. The nonlinear coupled weak solution equations are solved with FEM and the dynamic coefficients are obtained. Numerical simulation is operated and the change laws that the dynamic coefficients change with dimensionless perturbation frequency f, eccentricity ratio E h and other structure parameters are analyzed. This paper provides a reference and preparation for analysis on the dynamic characteristics of the similar gas bearings.

Study on wet gas online flow rate measurement based on dual slotted orifice plate

According to the current technical problems existing in gas and liquid flow measurement for wet gas production, the slotted orifice-couple flow meter was developed and the basic measurement principles for gas and liquid flow was presented. A new wet gas flow meter was developed based on the dual slotted orifice transducer. The flow characteristics of liquid flow through dual slotted orifice plate, the relationship of differential pressure between the dual slotted orifice plate, pressure, temperature, and flow rate of gas/liquid of different aperture ratio were studied. A mathematical measurement model was established to be applied in the flow meter measurement system with dual slotted orifice plate. The model was tested and calibrated by on-site field experiments in the China National Center of Metrology at Daqing Oil field. The results showed that the maximum measurement error of the gas and liquid flow was less than 10% and 15% respectively, when the Gas Volume Fraction (GVF) was greater than 90 vol%. The measurement accuracy of this industrial prototype can meet the requirements of well fluids.

Mechanical and water vapor barrier properties of extruded and heat-pressed gelatin films

Gelatin-based edible films were produced by extruding hot melt of gelatin-based resins through a die with slot orifice and followed by heat-pressed method. The resins were plasticized with glycerol, sorbitol and the mixture of glycerol and sorbitol (MGS). The effect of type of plasticizer on extruded and heat-pressed (EHP) film-forming capacity was studied, and the mechanical and water barrier properties of resulting EHP gelatin films were compared with those of gelatin films prepared by solution casting method. Stretchable films were formed when glycerol or MGS were used as plasticizer, whereas resins plasticized with sorbitol were extruded in non-stretchable sheets. Glycerol plasticized gelatin film showed the highest flexibility and transparency among the EHP films tested. Tensile strength (TS), elongation ( E) and water vapor permeability (WVP) of glycerol plasticized EHP gelatin films were 17.3 MPa, 215.9% and 2.46 ng m/m 2 s Pa, respectively, and EHP gelatin films had higher E values, lower TS values and higher WVP values compared to the glycerol plasticized cast gelatin films.

Wet Gas Meter Development Based on Slotted Orifice Couple and Neural Network Techniques

A slotted orifice has many superiorities over a standard orifice. For single-phase flow measurement, its flow coefficient is insensitive to the upstream velocity profile. For two phase flow measurement, various characteristics of its differential pressure (DP) are stable and closely correlated with the mass flow rate of gas and liquid. The complex relationships between the signal features and the two-phase flow rate are established through the use of a back propagation (BP) neural network. Experiments were carried out in the horizontal tubes with 50mm inner diameter, operated with water flow rate in the range of 0.2m 3.h -1 to 4m 3.h -1, gas flow rate in the range of 100m 3.h -1 to 1000m 3.h -1, and pressure at 400kPa and 850kPa respectively, where the temperature is ambient temperature. This article includes the principle of wet gas meter development, the experimental matrix, the signal processing techniques and the achieved results. On the basis of the results it is suggested that the slotted orifice couple with a trained neural network may provide a simple but efficient solution to the wet gas meter development.

Study on the metering characteristics of a slotted orifice for wet gas flow

Wet gas metering is a subset of multiphase flow metering. A slotted orifice is selected for the development of a wet gas meter (WGM). With the help of Computational Fluid Dynamics (CFD) technology, the static pressure, velocity and density contours across the slotted and the standard orifice flow meter have been analyzed. Based on the experimental data the two-phase multipliers of the slotted orifice have been investigated. Two new differential pressure correlations of the slotted orifice are put forward for the first time and appropriate conclusions are discussed.

Response of a slotted orifice flow meter to an air/water mixture

The ability of a flow meter to respond predictably to the presence of liquid and gas is important to the natural gas industry and to users of steam. In both cases, the gas can become saturated and some liquids can condense in the line. The response of orifice flow meters to the presence of liquids is erratic and produces considerable uncertainty. Turbine flow meters can sustain severe damage when subjected to two phase flow. The slotted orifice flow meter has been developed to address the problem of upstream flow conditioning. This device has been shown to be insensitive to the upstream velocity profile. To further evaluate the flow meter for use by the natural gas industry, the effects of adding liquid to a gas flow upon the meter performance has been investigated by subjecting a slotted orifice flow meter with an equivalent β ratio of 0.50 to a two phase flow consisting of air and water.

Exhaustion of a thin film of a nonlinear-viscous fluid from a slot with slipping relative to the underlying surface

The problem of exhaustion of a thin film of a non-Newtonian fluid with a power rheological law from a slotted orifice is solved with account of film slipping relative to the underlying surface. By the method of group analysis with transformation of the parameters entering the problem, an asymptotic formula for the film profile is obtained and a law of motion of the film edge with small slipping is derived.

A Versatile Flat-Deposit Impactor-Type Aerosol Collector Part 2: Calibration and Quantitative Study

The SPAL collector is a versatile impactor-type aerosol collector with rotatable substrate plates and radially aligned slot orifices. The airflow, controlled with a critical orifice at the last stage, becomes choked for an exit pressure of 0.5 atm or less. Monodisperse latex and methylene blue aerosols sampled on coated and uncoated aluminum foil substrates were used to determine the particle cutpoint diameters of each stage (9.0-0.07 mu m aed), loss on walls (3-7% for 0.054 mu m particles), and overall efficiency (97% from 0.3 to 7 mu m). Quantitative measurements were made with a spectrophotometer after recovering aerosols with a water and surfactant solution and with a semiautomated particle counting system using phase contrast microscopy. The experimental cutpoints and mea sured interstage pressures compare well with theory.

On the spreading of slotted jets

The cross-sectional shapes and velocity distributions of jets issuing from slotted orifices are examined. Hot wire anemometry and flow visualization are employed. The results indicate that for slots machined on thin tubes, the jets spread strongly in the transverse direction. Moreover, the jets appear to have kidney-shaped cross-sections, and double-peaked velocity distributions. Such slot designs may prove useful in applications where large impingement areas are required.

A microslot impactor for organic aerosol sampling

A microslot impactor has been designed with the objective of collecting large, concentrated samples suitable for chemical analysis of trace organic constituents. It employs a single slotted orifice per stage, with orifice widths as small as 0.1 mm. Using a relatively small pump (13 kg), five cutpoints from 0.1 to 3.5 μm are obtained at a flow rate of 361 min−1 (6 × 10−4 m3s−1). The microslot impactor operates with incompressible flow and minimal pressure drops for the upper four stages, and sonic flow through the last (fifth) stage. Measured cutpoints for the incompressible flow stages are somewhat higher than predicted, with critical Stokes numbers corresponding to 10 to 30% greater than theory.

Penetration and Mixing of Radial Jets in Neck-Down Cylindrical Crossflow

A parametric study of the penetration and mixing of radial jets in a neck-down cylindrical crossflow, which is characteristic of the quick-mix section in a generic tubular rich-burn/quick-mix/lean-burn combustor, is performed numerically. The parameters considered are the jet-to-crossflow momentum-flux ratio, number of injection orifices, neck-down ratio, swirling flow, and aspect ratio and orientation of radial slots. The analysis considers only nonreacting flows in order to concentrate on the fluid mechanics aspect of the processes, using temperature as a passive scalar to characterize the mixing performance. Laser-induced fluorescence experiments were also performed to verify the computational model. The results show that 1) the momentum-flux ratio has the most prominent effects on mixing performance, 2) there is a tradeoff between mixing effectiveness and pressure penalty, 3) the optimal configuration changes with the number of orifices and the slot aspect ratio, 4) an empirical optimal mixing correlation was developed for slotted orifices, 5) swirling flow does not improve mixing or pressure loss, and 6) necked-down sections do not necessarily enhance mixing but produce structural blockage, raising the pressure penalty. The implications of the parametric study on designing optimal mixer geometry are also discussed in terms of temperature and pressure penalty.

Slotted orifice flowmeter

AIChE JournalVolume 40, Issue 10 p. 1757-1760 R&D Note Slotted orifice flowmeter Gerald L. Morrison, Corresponding Author Gerald L. Morrison Turbomachinery Laboratory, Mechanical Engineering Dept., Texas A&M University, College Station, TX 77843Turbomachinery Laboratory, Mechanical Engineering Dept., Texas A&M University, College Station, TX 77843Search for more papers by this authorKenneth R. Hall, Kenneth R. Hall Turbomachinery Laboratory, Mechanical Engineering Dept., Texas A&M University, College Station, TX 77843Search for more papers by this authorJames C. Holste, James C. Holste Turbomachinery Laboratory, Mechanical Engineering Dept., Texas A&M University, College Station, TX 77843Search for more papers by this authorRobert E. DeOtte Jr., Robert E. DeOtte Jr. Turbomachinery Laboratory, Mechanical Engineering Dept., Texas A&M University, College Station, TX 77843Search for more papers by this authorMichael L. Macek, Michael L. Macek Turbomachinery Laboratory, Mechanical Engineering Dept., Texas A&M University, College Station, TX 77843Search for more papers by this authorLarry M. Ihfe, Larry M. Ihfe Turbomachinery Laboratory, Mechanical Engineering Dept., Texas A&M University, College Station, TX 77843Search for more papers by this author Gerald L. Morrison, Corresponding Author Gerald L. Morrison Turbomachinery Laboratory, Mechanical Engineering Dept., Texas A&M University, College Station, TX 77843Turbomachinery Laboratory, Mechanical Engineering Dept., Texas A&M University, College Station, TX 77843Search for more papers by this authorKenneth R. Hall, Kenneth R. Hall Turbomachinery Laboratory, Mechanical Engineering Dept., Texas A&M University, College Station, TX 77843Search for more papers by this authorJames C. Holste, James C. Holste Turbomachinery Laboratory, Mechanical Engineering Dept., Texas A&M University, College Station, TX 77843Search for more papers by this authorRobert E. DeOtte Jr., Robert E. DeOtte Jr. Turbomachinery Laboratory, Mechanical Engineering Dept., Texas A&M University, College Station, TX 77843Search for more papers by this authorMichael L. Macek, Michael L. Macek Turbomachinery Laboratory, Mechanical Engineering Dept., Texas A&M University, College Station, TX 77843Search for more papers by this authorLarry M. Ihfe, Larry M. Ihfe Turbomachinery Laboratory, Mechanical Engineering Dept., Texas A&M University, College Station, TX 77843Search for more papers by this author First published: October 1994 https://doi.org/10.1002/aic.690401015Citations: 9AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume40, Issue10October 1994Pages 1757-1760 RelatedInformation

Comparison of orifice and slotted plate flowmeters

The performance of a standard β = 0.50 orifice flowmeter is compared to the same flowmeter with a slotted orifice plate replacing the standard orifice plate. The slotted orifice plate has the same total open area as the standard plate and consists of three concentric rings, each of which contains several radial slots. The flow upstream of both orifice plates in preconditioned using a concentric pipe device to produce a wide range of axial velocity profiles without swirl. The discharge coefficient of the standard plate varies from the base value by −1% to +6%, while that of the slotted orifice plate varies by only ±0.25%. When swirl is generated upstream of the orifice plates, the discharge coefficients vary by 5% and 2% for the standard and slotted orifice plates, respectively. These data indicate that the slotted orifice flowmeter is superior to the standard orifice flowmeter in maintaining its calibration over a wide range of inlet flow conditions. The slotted orifice plate can be a ‘drop in’ replacement for a standard orifice plate.

Continuous potential discrete particle simulations of stress and velocity fields in hoppers: transition from fluid to granular flow

A number of numerical hopper discharge experiments were conducted using a novel simulation technique in which the individual circular disc particles are allowed to fill a two-dimensional hopper under gravity and are subsequently discharged through a central slot orifice. The novel aspect of the present technique is the incorporation of a continuous otential interaction for frictional granular flows which ensures the stability of contact mechanical force algorithms over much larger time steps than were hitherto possible. This is achieved by allowing softer interactions which vary on the same scale as the nominal particle size rather than the micro-contact scale used in the majority of previous literature. The resulting technique allows the filling and discharge events to be simulated over a sufficiently long time scale. The continuous potential confers on the particles an “excluded volume” which prevents excessive overlap. In addition, the effects of frictional forces are introduced via a tangential displacement vs force model similar to that developed by Mindlin for contacts of perfectly elastic spheres, but scaled to the normal potential interaction. Transition from fluid-like to granular flow is simulated by increasing the friction coefficient from zero. During both the filling and discharge stages of the simulation, the radial and tangential components of particle velocities are damped by a force proprotional to the relative particle velocities. The effects of material head in the hopper, the outlet size and the hopper half-angle were investigated to predict material discharge rates as well as the wall stress profiles during both filing and discharge. The effects of the ratio of the interparticle and wall friction coefficients on the prevailing flow and stress fields wree also investigated in both “mass-flow” and “funnel-flow” hoppers. Encouraging agreement was found between the simulation and experimental flow behaviour.