Estimating the Error Component Associated with the Selection of a Gas Flow Model in Critical Nozzles

Piston prover has been widely used as a gas flow standard for its advantages of high accuracy in standard volume, flow stability and repeatability. It has also been employed as the primary gas flow standard in many countries to calibrate meters. However, it is difficult to ensure the uniformity of the inside dimension of the piston, thus the application of conventional piston provers are limited by the maximum calibration flow generated by the piston cylinder volume. In this paper, an improved piston gas prover that mainly consists of two uniform plungers was proposed. Their external diameter constitutes the flow standard. The plungers are driven by servo motor, and the high speed fieldbus EtherCAT has been introduced as the control unit. Hence the two pistons could work collaboratively and operate in three modes: single-piston mode, double-pistons parallel mode, and double-pistons reciprocating mode. Besides generating steady-flow rate, the double-plunger prover can even produce an unsteady-flow rate which could be used to research the dynamic characteristics of flow meters. The structure and working principle of the three modes were carefully introduced. Then experiments for calibrating critical nozzles were carried out, and the results show that the repeatability of the discharge coefficient could be better than 0.06%, and the pressure fluctuation during the process was less than 50 Pa.

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A Hydrostatic Bearing With Compressible Fluid for Broad Application

Volume 4: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation; Education; IGTI Scholar Award ◽

10.1115/2001-gt-0250 ◽

2001 ◽

Author(s):

John S. Jacob ◽

Donald E. Bently ◽

John J. Yu

Keyword(s):

Compressible Fluid ◽

Gas Flow ◽

Flow Model ◽

Compressible Fluids ◽

Environmental Benefits ◽

Model Parameters ◽

Broad Application ◽

Hydrostatic Bearing ◽

Gas Bearing

The use of relatively inviscid, compressible fluids in externally-pressurized bearings has interesting possibilities for both OEM and retrofit applications. The chance to dramatically reduce mechanical losses and bearing heating, the elimination of oil from the process and installation, and the utilization of compressible process fluids as the supporting medium all have potential economic and environmental benefits. An experimental gas bearing rig was constructed to investigate the feasibility of some general applications. Clearance and orifice dimensions were selected based on a fairly simple gas flow model. Bently-Muszynska model parameters for the hydrostatic gas bearing were obtained through static-pull and non-synchronous perturbation testing.

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Optimization and Extended Applicability of Simplified Slug Flow Model for Liquid-Gas Flow in Horizontal and Near Horizontal Pipes

Energies ◽

10.3390/en13040842 ◽

2020 ◽

Vol 13 (4) ◽

pp. 842

Author(s):

Tea-Woo Kim ◽

Nam-Sub Woo ◽

Sang-Mok Han ◽

Young-Ju Kim

Keyword(s):

Slug Flow ◽

Pressure Loss ◽

Gas Flow ◽

Flow Model ◽

Flow Coefficient ◽

Coefficient Of Determination ◽

Liquid Holdup ◽

Two Phase ◽

Horizontal Pipes ◽

Image Velocimetry

The accurate prediction of pressure loss for two-phase slug flow in pipes with a simple and powerful methodology has been desired. The calculation of pressure loss has generally been performed by complicated mechanistic models, most of which require the iteration of many variables. The objective of this study is to optimize the previously proposed simplified slug flow model for horizontal pipes, extending the applicability to turbulent flow conditions, i.e., high mixture Reynolds number and near horizontal pipes. The velocity field previously measured by particle image velocimetry further supports the suggested slug flow model which neglects the pressure loss in the liquid film region. A suitable prediction of slug characteristics such as slug liquid holdup and translational velocity (or flow coefficient) is required to advance the accuracy of calculated pressure loss. Therefore, the proper correlations of slug liquid holdup, flow coefficient, and friction factor are identified and utilized to calculate the pressure gradient for horizontal and near horizontal pipes. The optimized model presents a fair agreement with 2191 existing experimental data (0.001 ≤ μL ≤ 0.995 Pa∙s, 7 ≤ ReM ≤ 227,007 and −9 ≤ θ ≤ 9), showing −3% and 0.991 as values of the average relative error and the coefficient of determination, respectively.

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A New Unified Diffusion—Viscous-Flow Model Based on Pore-Level Studies of Tight Gas Formations

SPE Journal ◽

10.2118/149223-pa ◽

2012 ◽

Vol 18 (01) ◽

pp. 38-49 ◽

Cited By ~ 42

Author(s):

Mohammad R. Rahmanian ◽

Roberto Aguilera ◽

Apostolos Kantzas

Keyword(s):

Porous Media ◽

Viscous Flow ◽

Flow Regime ◽

Gas Flow ◽

Flow Model ◽

Molecular Flow ◽

Single Element ◽

Free Molecular Flow ◽

Flow Through ◽

Tight Porous Media

Summary In this study, single-phase gas-flow simulation that considers slippage effects through a network of slots and microfractures is presented. The statistical parameters for network construction were extracted from petrographic work in tight porous media of the Nikanassin Group in the Western Canada Sedimentary Basin (WCSB). Furthermore, correlations between Klinkenberg slippage effect and absolute permeability have been developed as well as a new unified flow model in which Knudsen number acts implicitly as a flow-regime indicator. A detailed understanding of fluid flow at microscale levels in tight porous media is essential to establish and develop techniques for economic flow rate and recovery. Choosing an appropriate equation for flow through a single element of the network is crucial; this equation must include geometry and other structural features that affect the flow as well as all variation of fluid properties with pressure. Disregarding these details in a single element of porous media can easily lead to flow misinterpretation at the macroscopic scale. Because of the wide flow-path-size distribution in tight porous media, a variety of flow regimes can exist in the equivalent network. Two distinct flow regimes, viscous flow and free molecular flow, are in either side of this flow-regime spectrum. Because the nature of these two types of flow is categorically different, finding/adjusting a unified flow model is problematic. The complication stems from the fact that the viscosity concept misses its meaning as the flow regime changes from viscous to free molecular flow in which a diffusion-like mechanism dominates. For each specified flow regime, the appropriate equations for different geometries are studied. In addition, different unified flow models available in the literature are critically investigated. Simulation of gas flow through the constructed network at different mean flow pressures leads to investigating the functionality of the Klinkenberg factor with permeability of the porous media and pore-level structure.

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Pressure behavior of shale-gas flow in dual porous medium based on fractal theory

Interpretation ◽

10.1190/int-2018-0002.1 ◽

2018 ◽

Vol 6 (4) ◽

pp. SN1-SN10 ◽

Cited By ~ 2

Author(s):

Peiqing Lian ◽

Taizhong Duan ◽

Rui Xu ◽

Linlin Li ◽

Meng Li

Keyword(s):

Shale Gas ◽

Gas Flow ◽

Flow Model ◽

Fractal Theory ◽

Adsorption Coefficient ◽

Gas Reservoir ◽

Transition Stage ◽

Transition Section ◽

Shale Gas Reservoir ◽

Straight Line

The shale gas reservoir is a complex subject with a multiscale nanopore and fracture system, and the gas flow mechanism indicates an evident difference from the conventional gas reservoir. We have introduced fractal theory to characterize the multiscale distribution of pores and fractures, and we have developed a single-phase radial flow model considering nonequilibrium adsorption to describe the flow characteristics in the shale gas reservoir. The numerical solution of the flow model in Euclidean space is obtained by inversing the analytical solution derived in Laplace space through the Stehfest numerical inversion method, and the log-log curve of the dimensionless bottom-hole pressure (BHP) and its derivative versus dimensionless time are analyzed. The log-log curve of the dimensionless BHP has two distinct straight-line segments: The unit slope line reflects early well-storage effect, and the straight line with slope [Formula: see text] reflects reservoir fractal characteristics. The slope of the straight line will become smaller with the increasing fractal dimension. The adsorption coefficient mainly affects the middle and late period of the log-log curves, and more shale gas will desorb from the matrix with the increasing adsorption coefficient. The wellbore storage coefficient has a significant negative correlation with dimensionless BHP especially at the early and transitional stages. The skin factor mainly affects the transition section; a smaller skin factor generally leads to the earlier appearance of the transition section. In addition, a smaller interporosity flow coefficient also results in an earlier transition stage appearance. The lower storativity ratio means a higher dimensionless BHP and an earlier appearance of the transition stage.

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Microcatheter shaping using intravascular placement during intracranial aneurysm coiling

Interventional Neuroradiology ◽

10.1177/1591019917689926 ◽

2017 ◽

Vol 23 (3) ◽

pp. 249-254 ◽

Cited By ~ 6

Author(s):

Shinya Yamaguchi ◽

Osamu Ito ◽

Yuya Koyanagi ◽

Katsuma Iwaki ◽

Koichiro Matsukado

Keyword(s):

Flow Model ◽

Shape Change ◽

Three Dimensional ◽

Bend Angle ◽

Parent Artery ◽

Rotational Angiography ◽

Coil Embolisation ◽

Aneurysm Coiling ◽

Over Time ◽

Selection Of

Background The selection of a pre-shaped microcatheter or a shaping method must be carefully considered for successful aneurysm coiling. The objective of this report is to verify the use of intravascular placement to establish an appropriate microcatheter shape. Methods Fifteen patients (15 aneurysms) were included in this study because of the predicted difficulty of microcatheter insertion and stabilisation. The SL-10 straight microcatheter was inserted into the parent artery until the tip of the catheter passed through the neck of the aneurysm. After 5 minutes, the microcatheter was pulled out and the shape acquired from intravascular placement was confirmed and compared with the three-dimensional rotational angiography. In addition, the microcatheter tip was steam-shaped for coiling and coil embolisation was performed. A silicone flow model was also used to confirm our findings. The first experiment compared the bend angle in four different microcatheters placed in the model for 5 minutes. In the second experiment, the SL-10 straight microcatheter was placed in the model, and the bend angle was measured at 2.5, 5, 7.5 and 10 minutes to observe the changes in bend angle over time. Results The SL-10 straight microcatheter, in place for 5 minutes, acquired a shape similar to the patient’s own vessel. Among the 15 patients included, 13 were treated using an intravascular shaped microcatheter. In the flow model experiments, the SL-10 most easily acquired the vessel shape, and the shape change stabilised after 5 minutes. Conclusion Shaping the SL-10 straight microcatheter using intravascular placement is an effective shaping method for aneurysm coil embolisation.

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