Assessment of Cavitation Models for Flows in Diesel Injectors With Single- and Two-Fluid Approaches

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Kaushik Saha ◽  
Xianguo Li
Keyword(s):  
Fluid Model ◽  
Injection Pressure ◽  
Experimental Results ◽  
The Other ◽  
Computational Time ◽  
Two Phase ◽  
Numerical Predictions ◽  
Mass Flow Rates ◽  
Two Phases ◽  
Two Fluid

Several recent cavitation models for the analysis of two-phase flows in diesel injectors with single- and two-fluid modeling approaches have been evaluated, including the Saha–Abu-Ramandan–Li (SAL), Schnerr–Sauer (SS), and Zwart–Gerber–Belamri (ZGB) models. The SAL model is a single-fluid model, while the other two models have been implemented with both single- and two-fluid approaches. Numerical predictions are compared with experimental results available in literature, qualitatively with experimental images of two-phase flow in an optically accessible nozzle, and quantitatively with measured mass flow rates and velocity profiles. It is found that at low injection pressure differentials there can be considerable discrepancy in the predictions of the vapor distribution from the three models considered. This discrepancy is reduced as the injection pressure differential is increased. Implementation of the SS and ZGB models with single- and two- fluid approaches yields noticeable differences in the results because of the relative velocity between the two phases, with two-fluid approach providing better agreement with experimental results. The performance of the SS and ZGB models implemented with the two-fluid approach is comparable with the SAL single-fluid model, but with significantly more computational time. Overall, the SAL single-fluid model performs comparatively better with respect to the other two models.

scholarly journals Natural modes of the two-fluid model of two-phase flow

2021 ◽  
Vol 33 (3) ◽  
pp. 033324
Author(s):  
Alejandro Clausse ◽  
Martín López de Bertodano
Keyword(s):  
Two Phase Flow ◽  
Fluid Model ◽  
Phase Flow ◽  
Two Phase ◽  
Natural Modes ◽  
Two Fluid Model ◽  
Two Fluid

Two-Phase Flows in Mini-/Micro-Gas Flow Channels of PEM Fuel Cells

2013 ◽  
Author(s):  
Sung Chan Cho ◽  
Yun Wang
Keyword(s):  
Pressure Drop ◽  
Gas Flow ◽  
Fluid Model ◽  
Pem Fuel Cells ◽  
Two Phase ◽  
Micro Gas Flow ◽  
Two Fluid Model ◽  
The Impact ◽  
Two Fluid ◽  
Phase Pressure

In this paper, two-phase flow dynamics in a micro channel with various wall conditions are both experimentally and theoretically investigated. Annulus, wavy and slug flow patterns are observed and location of liquid phase on different wall condition is visualized. The impact of flow structure on two-phase pressure drop is explained. Two-phase pressure drop is compared to a two-fluid model with relative permeability correlation. Optimization of correlation is conducted for each experimental case and theoretical solution for the flows in a circular channel is developed for annulus flow pattern showing a good match with experimental data in homogeneous channel case.

A Physically Based, One-Dimensional Two-Fluid Model for Direct Contact Condensation of Steam Jets Submerged in Subcooled Water

2015 ◽  
Vol 1 (2) ◽  
Author(s):  
David Heinze ◽  
Thomas Schulenberg ◽  
Lars Behnke
Keyword(s):  
Direct Contact ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Interfacial Area ◽  
Phase Flow ◽  
Two Phase ◽  
One Dimensional ◽  
Two Fluid Model ◽  
Contact Condensation ◽  
Two Fluid

A simulation model for the direct contact condensation of steam in subcooled water is presented that allows determination of major parameters of the process, such as the jet penetration length. Entrainment of water by the steam jet is modeled based on the Kelvin–Helmholtz and Rayleigh–Taylor instability theories. Primary atomization due to acceleration of interfacial waves and secondary atomization due to aerodynamic forces account for the initial size of entrained droplets. The resulting steam-water two-phase flow is simulated based on a one-dimensional two-fluid model. An interfacial area transport equation is used to track changes of the interfacial area density due to droplet entrainment and steam condensation. Interfacial heat and mass transfer rates during condensation are calculated using the two-resistance model. The resulting two-phase flow equations constitute a system of ordinary differential equations, which is solved by means of the explicit Runge–Kutta–Fehlberg algorithm. The simulation results are in good qualitative agreement with published experimental data over a wide range of pool temperatures and mass flow rates.

Numerical Simulation of Boiling Two-Phase Flow in Tight-Lattice Rod Bundle by 3-Dimensional Two-Fluid Model Code ACE-3D

2008 ◽  
Author(s):  
Hiroyuki Yoshida ◽  
Takeharu Misawa ◽  
Kazuyuki Takase
Keyword(s):  
Void Fraction ◽  
Lift Force ◽  
Fluid Model ◽  
Phase Flow ◽  
Two Phase ◽  
Rod Bundle ◽  
Fraction Distribution ◽  
Two Fluid Model ◽  
Tight Lattice ◽  
Two Fluid

Two-fluid model can simulate two phase flow less computational cost than inter-face tracking method and particle interaction method. Therefore, two-fluid model is useful for thermal hydraulic analysis in large-scale domain such as a rod bundle. Japan Atomic Energy Agency (JAEA) develops three dimensional two-fluid model analysis code ACE-3D, which adopts boundary fitted coordinate system in order to simulate complex shape channel flow. In this paper, boiling two-phase flow analysis in a tight lattice rod bundle is performed by ACE-3D code. The parallel computation using 126CPUs is applied to this analysis. In the results, the void fraction, which distributes in outermost region of rod bundle, is lower than that in center region of rod bundle. At height z = 0.5 m, void fraction in the gap region is higher in comparison with that in center region of the subchannel. However, at height of z = 1.1m, higher void fraction distribution exists in center region of the subchannel in comparison with the gap region. The tendency of void fraction to concentrate in the gap region at vicinity of boiling starting point, and to move into subchannel as water goes through rod bundle, is qualitatively agreement with the measurement results by neutron radiography. To evaluate effects of two-phase flow model used in ACE-3D code, numerical simulation of boiling two-phase in tight lattice rod bundle with no lift force model (neglecting lift force acting on bubbles) is also performed. From the comparison of numerical results, it is concluded that the effects of lift force model are not so large on overall void fraction distribution in tight lattice rod bundle. However, higher void fraction distribution in center region of the subchannel was not observed in this simulation. It is concluded that the lift force model is important for local void fraction distribution in rod bundles.

Prediction of Parameters Distribution of Upward Boiling Two-Phase Flow With Two-Fluid Models

2002 ◽  
Author(s):  
Wei Yao ◽  
Christophe Morel
Keyword(s):  
Void Fraction ◽  
Fluid Model ◽  
Constitutive Relations ◽  
Turbulent Dispersion ◽  
Dispersion Force ◽  
Liquid Temperature ◽  
Two Phase ◽  
Radial Profiles ◽  
Two Fluid Model ◽  
Two Fluid

In this paper, a multidimensional two-fluid model with additional turbulence k–ε equations is used to predict the two-phase parameters distribution in freon R12 boiling flow. The 3D module of the CATHARE code is used for numerical calculation. The DEBORA experiment has been chosen to evaluate our models. The radial profiles of the outlet parameters were measured by means of an optical probe. The comparison of the radial profiles of void fraction, liquid temperature, gas velocity and volumetric interfacial area at the end of the heated section shows that the multidimensional two-fluid model with proper constitutive relations can yield reasonably predicted results in boiling conditions. Sensitivity tests show that the turbulent dispersion force, which involves the void fraction gradient, plays an important role in determining the void fraction distribution; and the turbulence eddy viscosity is a significant factor to influence the liquid temperature distribution.

Resistive transition broadening in two-phase polycrystalline YBaCuO

1993 ◽  
Vol 8 (5) ◽  
pp. 957-961 ◽  
Author(s):  
J.C. Abele ◽  
R.L. Bristol ◽  
T.C. Nguyen ◽  
M.W. Ohmer ◽  
L.S. Wood
Keyword(s):  
Magnetic Fields ◽  
Computer Models ◽  
Structured Data ◽  
The Other ◽  
Critical Ratio ◽  
Resistive Transition ◽  
Two Phase ◽  
Two Phases

A model proposed by Tinkham1to explain the resistance versus temperature broadening found in highTcsuperconductors in applied magnetic fields is extended to “foot and knee”-structured data taken on polycrystalline YBa2Cu3O6+δ. The proposed extension involves a series combination of two types of superconductors. For this series combination to result, a critical ratio of the two types of superconductors must be met—a result common to both percolation and randomized cellular autonoma theory. This critical ratio is investigated via statistical computer models of a polycrystalline superconductor having two phases of crystallites—one with substantially lowerJcthan the other.

Dynamics of the Internal Flow in Swirl Atomizers by CFD Simulations

2018 ◽  
pp. 100-132
Author(s):  
Roman Ivanovitch Savonov
Keyword(s):  
Numerical Simulation ◽  
Homogeneous Model ◽  
Internal Flow ◽  
Surface Model ◽  
Cfd Simulations ◽  
Two Phase ◽  
Two Phases ◽  
Swirl Atomizer ◽  
Free Surface Model ◽  
Two Fluid

This work presents the simulation of the internal flow in a swirl atomizer. The geometry of the atomizer is calculated by analytical equations used in engineering. The numerical simulation of the two-phase flow is performed by using two equations k-ε turbulence model. The fluids are presented as two-fluid homogeneous model. The interface between two phases is calculated by free surface model. The distribution fields of the axial and tangential velocities, pressures and air core are obtained. The aim of this work is to compare the results obtained by numerical simulation with ones obtained analytically. Also, to study the internal fluids flow inside the atomizer.

A novel astrophysics-based framework for prediction of binding affinity of glucose binder

2020 ◽  
Vol 34 (31) ◽  
pp. 2050346
Author(s):  
Rajesh Kondabala ◽  
Vijay Kumar ◽  
Amjad Ali ◽  
Manjit Kaur
Keyword(s):  
Decision Tree ◽  
Binding Affinity ◽  
Cross Validation ◽  
Learning Strategy ◽  
Experimental Results ◽  
The Other ◽  
Computational Time ◽  
Glucose Binding ◽  
Regression Algorithms

In this paper, a novel astrophysics-based prediction framework is developed for estimating the binding affinity of a glucose binder. The proposed framework utilizes the molecule properties for predicting the binding affinity. It also uses the astrophysics-learning strategy that incorporates the concepts of Kepler’s law during the prediction process. The proposed framework is compared with 10 regression algorithms over ZINC dataset. Experimental results reveal that the proposed framework provides 99.30% accuracy of predicting binding affinity. However, decision tree provides the prediction with 97.14% accuracy. Cross-validation results show that the proposed framework provides better accuracy than the other existing models. The developed framework enables researchers to screen glucose binder rapidly. It also reduces computational time for designing small glucose binding molecule.

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