scholarly journals An Explicit Analytical Solution for Transient Two-Phase Flow in Inclined Fluid Transmission Lines

Fluids ◽  
2021 ◽  
Vol 6 (9) ◽  
pp. 300
Author(s):  
Taoufik Wassar ◽  
Matthew A. Franchek ◽  
Hamdi Mnasri ◽  
Yingjie Tang
Keyword(s):  
Steady State ◽  
Analytical Model ◽  
Transmission Lines ◽  
Single Phase ◽  
Flow Model ◽  
Two Phase Flow ◽  
Mechanistic Model ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase

Due to the complex nonlinearity characteristics, analytical modeling of compressible flow in inclined transmission lines remains a challenge. This paper proposes an analytical model for one-dimensional flow of a two-phase gas-liquid fluid in inclined transmission lines. The proposed model is comprised of a steady-state two-phase flow mechanistic model in-series with a dynamic single-phase flow model. The two-phase mechanistic model captures the steady-state pressure drop and liquid holdup properties of the gas-liquid fluid. The developed dynamic single-phase flow model is an analytical model comprised of rational polynomial transfer functions that are explicitly functions of fluid properties, line geometry, and inclination angle. The accuracy of the fluid resonant frequencies predicted by the transient flow model is precise and not a function of transmission line spatial discretization. Therefore, model complexity is solely a function of the number of desired modes. The dynamic single-phase model is applicable for under-damped and over-damped systems, laminar, and turbulent flow conditions. The accuracy of the overall two-phase flow model is investigated using the commercial multiphase flow dynamic code OLGA. The mean absolute error between the two models in step response overshoot and settling time is less than 8% and 2 s, respectively.

A computationally efficient two-phase hydro-sediment-morphdynamic model and its preliminary field applications  

2021 ◽  
Author(s):  
Binghan Lyu ◽  
Peng Hu ◽  
Ji Li ◽  
Zhixian Cao ◽  
Wei Li ◽  
...  
Keyword(s):  
Yangtze River ◽  
Single Phase ◽  
Flow Model ◽  
Two Phase Flow ◽  
Measure Data ◽  
Special Focus ◽  
Phase Flow ◽  
Computationally Efficient ◽  
Single Phase Flow ◽  
Two Phase

<p>While fluvial flows carrying relatively coarse sediments involve strong two-phase interactions, existing numerical modeling in the field-scale is mostly based on quasi-single phase flow model. Here a computationally efficient two-phase hydro-sediment-morphodynamic model is developed with a special focus on field applications. The hybrid LTS/GMaTS method originally developed for quasi-single flow model is extended to the present two-phase flow model, of which the achieved reduction in the computational cost facilitates the present field applications in the Taipingkou Waterway, Middle Yangtze River. To overcome numerical instabilities arising from the relatively large spatial and time steps in field case that lead to an issue of stiff source term, the following numerical treatments are proposed: implementation of theoretically-derived lower and upper limits for the inter-phase interactive forces. Moreover, to improve the numerical accuracy, the HLLC approximate Riemann solver is used for the water phase, whereas the FORCE solver is used for the sediment phase. Both the present two-phase flow model and the existing quasi-single-phase flow model are applied to a series of typical cases, including refilling of a dredged trench, a full dam-break flow in an abruptly widening channel and reproduction of the Taipingkou waterway, Middle Yangtze River. Compared with the quasi-single-phase flow model, the two-phase flow model has better performance as compared to the measure data and has more profound physical significance.</p>

Experimental Study on Heat Transfer of Single-Phase Flow and Boiling Two-Phase Flow in Vertical Narrow Annuli

2002 ◽  
Author(s):  
Suizheng Qiu ◽  
Minoru Takahashi ◽  
Guanghui Su ◽  
Dounan Jia
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Two Phase Flow ◽  
Annular Channel ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Narrow Annuli ◽  
Narrow Gaps

Water single-phase and nucleate boiling heat transfer were experimentally investigated in vertical annuli with narrow gaps. The experimental data about water single-phase flow and boiling two-phase flow heat transfer in narrow annular channel were accumulated by two test sections with the narrow gaps of 1.0mm and 1.5mm. Empirical correlations to predict the heat transfer of the single-phase flow and boiling two-phase flow in the narrow annular channel were obtained, which were arranged in the forms of the Dittus-Boelter for heat transfer coefficients in a single-phase flow and the Jens-Lottes formula for a boiling two-phase flow in normal tubes, respectively. The mechanism of the difference between the normal channel and narrow annular channel were also explored. From experimental results, it was found that the turbulent heat transfer coefficients in narrow gaps are nearly the same to the normal channel in the experimental range, and the transition Reynolds number from a laminar flow to a turbulent flow in narrow annuli was much lower than that in normal channel, whereas the boiling heat transfer in narrow annular gap was greatly enhanced compared with the normal channel.

Turbulence Structure of a Liquid-Solid Two-Phase Jet by Means of Laser Techniques

2003 ◽  
Author(s):  
Toshimichi Arai ◽  
Naoki Kudo ◽  
Tsuneaki Ishima ◽  
Ismail M. Youssef ◽  
Tomio Obokata ◽  
...  
Keyword(s):  
Particle Size ◽  
Single Phase ◽  
Two Phase Flow ◽  
Volume Ratio ◽  
Water Phase ◽  
Phase Flow ◽  
Size Discrimination ◽  
Single Phase Flow ◽  
Particle Volume ◽  
Two Phase

Characteristics on particle motion in a liquid-solid two-phase jet flow were studied in the paper. The water jet including glass particle of 389 μm in mean diameter was injected into water bath. The experimental conditions were 0.21% of initial particle volume ratio, 5mm in pipe diameter and 1.84 m/s of mean velocity on outlet of the jet. A laser Doppler anemometer (LDA) with size discrimination was applied for measuring the time serious velocities of the single-phase flow, particle and water phase flow. A particle image velocimetry (PIV) was also applied in the two-phase flow. The normal PIV method can hardly measure the particle size and perform the particle size discrimination. In the experiment, using the gray scales related with the scattering light intensity, measuring method with size discrimination in two-phase flow was carried out. The experimental results show less difference between velocities of single-phase flow and water-phase flow under this low particle volume ratio condition. Particles have the relative motion with the water-phase and large rms velocity. The PIV used in this experiment, which is called multi-intensity-layer-PIV: MILP, can measure water-phase velocity with good accuracy.

Research on Two-Phase Flow Induced Vibration Characteristics of U-Tube Bundles

2017 ◽  
Author(s):  
Jiang Nai-bin ◽  
Gao Li-xia ◽  
Huang Xuan ◽  
Zang Feng-gang ◽  
Xiong Fu-rui
Keyword(s):  
Upper Bound ◽  
Single Phase ◽  
Two Phase Flow ◽  
Tube Bundle ◽  
Upper Bounds ◽  
Vibration Response ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase ◽  
Tube Bundles

In steam generators and other heat exchangers, there are a lot of tube bundles subjected to two-phase cross-flow. The fluctuating pressure on tube bundle caused by turbulence can induce structural vibration. The experimental data from a U-tube bundle of steam generator in air-water flow loop are analyzed in this work. The different upper bounds of buffeting force are used to calculate the turbulence buffeting response of U-tubes, and the calculation results are compared with the experimental results. The upper bounds of buffeting force include one upper bound based on single-phase flow, and two upper bounds based on two-phase flow. It is shown that the upper bound based on single-phase flow seriously underestimated the turbulence excitation, the calculated vibration response is much less than the experimental measurement. On the other hand, the vibration response results calculated with the upper bounds based on two-phase flow are closer to the measured results under most circumstances.

Development of Sodium Two-Phase Flow Model for KALIMER Core Analysis

2002 ◽  
Author(s):  
W. P. Chang ◽  
Dohee Hahn
Keyword(s):  
Liquid Metal ◽  
Single Phase ◽  
System Analysis ◽  
Flow Model ◽  
Two Phase Flow ◽  
Water System ◽  
Phase Flow ◽  
Two Phase ◽  
Applicable Range ◽  
Further Development

An algorithm for sodium boiling is developed in order to extend the applicability of SSC-K, which is a main system analysis code for the KALIMER (Korea Advanced LIquid MEtal Reactor) conceptual design. As the capability of the current SSC-K version is limited to simulation of only a single-phase sodium flow, its applicable range should not be enough to assess the fuel integrity under some of HCDA (Hypothetical Core Disruptive Accident) initiating events where sodium boiling is anticipated. The two-phase flow model similar to that used for the light water system is known to be no more effective directly to liquid metal reactors, because the phenomena observed between two reactor coolant systems are definitely different. The developing algorithm is based on a multiple-bubble slug ejection model, which allows a finite number of bubbles in a channel at any time. The present work is a continuous effort following the former study to confirm a qualitative acceptance on the model. Since the model has been applied only to the active fuel region in the former study, a part of its qualification seems to have already been demonstrated. For its application to the whole KALIMER core channel, however, the model needs to be examined the applicability to the fuel regions other than the active fuel. The present study primarily focuses on that point. In a result, although the model may be improved in a sense through the present study over the previous modeling, a clear limitation is also confirmed with the validity of the model. The further development, therefore, is required for this model to achieve its goal by resolving such limitations.

Low-Dimensional Modeling of Transient Two-Phase Flow in Pipelines

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Amine Meziou ◽  
Majdi Chaari ◽  
Matthew Franchek ◽  
Rafik Borji ◽  
Karolos Grigoriadis ◽  
...  
Keyword(s):  
Steady State ◽  
Multiphase Flow ◽  
Transmission Line ◽  
Transmission Lines ◽  
Mechanistic Model ◽  
Phase Flow ◽  
Liquid Holdup ◽  
Two Phase ◽  
Low Dimensional ◽  
State Pressure

Presented are reduced-order models of one-dimensional transient two-phase gas–liquid flow in pipelines. The proposed model is comprised of a steady-state multiphase flow mechanistic model in series with a transient single-phase flow model in transmission lines. The steady-state model used in our formulation is a multiphase flow mechanistic model. This model captures the steady-state pressure drop and liquid holdup estimation for all pipe inclinations. Our implementation of this model will be validated against the Stanford University multiphase flow database. The transient portion of our model is based on a transmission line modal model. The model parameters are realized by developing equivalent fluid properties that are a function of the steady-state pressure gradient and liquid holdup identified through the mechanistic model. The model ability to reproduce the dynamics of multiphase flow in pipes is evaluated upon comparison to olga, a commercial multiphase flow dynamic code, using different gas volume fractions (GVF). The two models show a good agreement of the steady-state response and the frequency of oscillation indicating a similar estimation of the transmission line natural frequency. However, they present a discrepancy in the overshoot values and the settling time due to a difference in the calculated damping ratio. The utility of the developed low-dimensional model is the reduced computational burden of estimating transient multiphase flow in transmission lines, thereby enabling real-time estimation of pressure and flow rate.

Measurement of Pressure Loss Throughout a Clogged Steam Generator Tube Support Plate in Single Phase Flow

2010 ◽  
Author(s):  
Olivier Brunin ◽  
Geoffrey Deotto ◽  
Franck David ◽  
Joe¨l Pillet ◽  
Gilles Dague ◽  
...  
Keyword(s):  
Pressure Loss ◽  
Single Phase ◽  
Experimental Approach ◽  
Two Phase Flow ◽  
Loss Coefficient ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Steam Generators ◽  
Two Phase ◽  
Pressure Loss Coefficient

After a period of several years of operation, steam generators can be affected by fouling and clogging. Fouling means that deposits of sludge accumulate on tubes or tube support plates (TSP). That results in a reduction of heat exchange capabilities and can be modelled by means of a fouling factor. Clogging is a reduction of flow free area due to an accumulation of sludge in the space between TSP and tubes. The increase of the clogging ratio results in an increase of the overall TSP pressure loss coefficient. The link between the clogging ratio and the overall TSP pressure loss coefficient is the most important aspect of our capability to accurately calculate the thermal-hydraulics of clogged steam generators. The aim of the paper is to detail the experimental approach chosen by EDF and AREVA NP to address the calculation uncertainties. The calculation method is classically based on the computation of a single-phase (liquid-only) pressure loss coefficient, which is multiplied by a two-phase flow factor. Both parameters are well documented and can be derived on the basis of state of the art methods such as IDEL’CIK diagrams and CHISHOLM formula. The experimental approach consists of a validation of the correlations by performing tests on a mock-up section with an upward flow throughout a vertical array of tubes. A mixture of water and vapour refrigerant R116 is used to represent two-phase flows. The tube bundle is composed of a 25 tubes array in a square arrangement. The overall height of the mock-up is 2 m. Eight test TSPs were manufactured, considering eight different clogging configurations: six plates with a typical clogging profile at six clogging ratios (0, 44%, 58%, 72%, 86%, 95%), and two plates with a clogging ratio of 72% associated with two different clogging profiles (large bending radius profile and rectangular profile). A series of tests were performed in 2009 in single-phase flow conditions. Two-phase flow tests with a mixture of liquid water and vapour refrigerant R116 will be performed in 2010. The paper illustrates the main results obtained during the single-phase tests performed in 2009.

scholarly journals Two-Phase Flow Simulations Using 1D Centerline-Based C- and U-Shaped Pipe Meshes

2021 ◽  
Vol 11 (5) ◽  
pp. 2020
Author(s):  
Thinh Quy Duc Pham ◽  
Jichan Jeon ◽  
Daeseong Jo ◽  
Sanghun Choi
Keyword(s):  
Mesh Generation ◽  
Single Phase ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Dynamic Pressure ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase ◽  
Two Fluid Model ◽  
Two Fluid

This study aims to investigate the pressure changes, bubble dynamics, and flow physics inside the U- and C-shaped pipes with four different gravitational directions. The simulation is performed using a 1D centerline-based mesh generation technique along with a two-fluid model in the open-source software, OpenFOAM v.6. The continuity and momentum equations of the two-fluid model are discretized using the pressure-implicit method for the pressure-linked equation algorithm. The static and hydrostatic pressures in the two-phase flow were consistent with those of single-phase flow. The dynamic pressure in the two-phase flow was strongly influenced by the effect of the buoyancy force. In particular, if the direction of buoyancy force is the same as the flow direction, the dynamic pressure of the air phase increases, and that of the water phase decreases to satisfy the law of conservation of mass. Dean flows are observed on the transverse plane of the curve regions in both C-shaped and U-shaped pipes. The turbulent kinetic energy is stronger in a two-phase flow than in a single-phase flow. Using the 1D centerline-based mesh generation technique, we demonstrate the changes in pressure and the turbulent kinetic energy of the single- and two-phase flows, which could be observed in curve pipes.

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