Numerical Investigation of Non-Isothermal Cavitating Flows on Hydrofoils by Means of an Extended Schnerr-Sauer Model Coupled With a Nucleation Model

2018 ◽  
Author(s):  
Maria Grazia De Giorgi ◽  
Antonio Ficarella ◽  
Donato Fontanarosa
Keyword(s):  
Mass Transfer ◽  
Heat Source ◽  
Temperature Drop ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Transfer Model ◽  
Uniform Field ◽  
Cavitating Flows ◽  
Two Phase ◽  
Vapor Cavity

The present work aims to investigate cavitating flows of water, liquid hydrogen and nitrogen on hydrofoils numerically, using the open source code OpenFOAM. The Eulerian homogeneous mixture approach has been used, consisting in a mass transfer model which is based on the combination of a two-phase incompressible unsteady solver with a Volume of Fluid (VOF) interface tracking method. Thermal effects have been introduced by means of the activation of energy equation and latent heat source terms plus convective heat source term. The dependency of the saturation conditions to the temperature has been defined using Antoine-like equations. An extended Schnerr-Sauer model based on the Classical Nucleation Theory (CNT) has been implemented for the computation of the interfacial mass transfer rates. In order to investigate the nucleation effects, an extension of the Classical Nucleation Theory has been considered by coupling the Population Balance Equation/Extended Quadrature-Based Method of Moments (PBE-EQBMM) with the CFD model, which has been defined in combination with a transport equation for the nuclei density. Results showed that nucleation determined a non-uniform field of nuclei density so as to produce a reduction of the temperature drop inside the vapor bubbles, as well as a warmed wake downstream the vapor cavity. Unsteady computations also revealed an influence of the nucleation on the dynamics of the vapor cavity and the bubble detachment.

Numerical Investigation of Nonisothermal Cavitating Flows on Hydrofoils by Means of an Extended Schnerr–Sauer Model Coupled With a Nucleation Model

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Maria Grazia De Giorgi ◽  
Antonio Ficarella ◽  
Donato Fontanarosa
Keyword(s):  
Mass Transfer ◽  
Heat Source ◽  
Temperature Drop ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Transfer Model ◽  
Nonuniform Field ◽  
Cavitating Flows ◽  
Two Phase ◽  
Vapor Cavity

Abstract This work aimed to investigate cavitating flows of water, liquid hydrogen, and nitrogen on hydrofoils numerically, using the open source code openfoam. The Eulerian homogeneous mixture approach has been used, consisting in a mass transfer model, which is based on the combination of a two-phase incompressible unsteady solver with a volume of fluid interface tracking method. Thermal effects have been introduced by means of the activation of energy equation and latent heat source terms plus convective heat source term. The dependency of the saturation conditions to the temperature has been defined using Antoine-like equations. An extended Schnerr–Sauer model based on the classical nucleation theory (CNT) has been implemented for the computation of the interfacial mass transfer rates. In order to investigate the nucleation effects, an extension of the CNT has been considered by coupling the population balance equation (PBE)/extended quadrature-based method of moments with the computational fluid dynamics (CFD) model, which has been defined in combination with a transport equation for the nuclei density. Results showed that nucleation determined a nonuniform field of nuclei density so as to produce a reduction of the temperature drop inside the vapor bubbles, as well as a warmed wake downstream the vapor cavity. Unsteady computations also revealed an influence of the nucleation on the dynamics of the vapor cavity and the bubble detachment.

The Effect of Turbulence and Real Gas Models on the Two Phase Spontaneously Condensing Flows in Nozzle

2013 ◽  
Author(s):  
Yogini Patel ◽  
Giteshkumar Patel ◽  
Teemu Turunen-Saaresti
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Navier Stokes ◽  
Two Phase ◽  
Real Gas ◽  
Spontaneous Condensation ◽  
Condensing Flows ◽  
Computational Fluid Dynamics Cfd

The aim of the paper is to analyse the effect of turbulence and real gas models on the process of spontaneous condensation in converging diverging (CD) nozzle by using commercial Computational Fluid Dynamics (CFD) code. The calculations were based on the 2-D compressible Navier-Stokes (NS) equations coupled with two-equation turbulence model, and the non-equilibrium spontaneous condensing steam flow was solved on the basis of the classical nucleation theory. The results were validated to the available experimental data.

Stress and pore pressure in saturated clay subjected to heat from radioactive waste: a numerical simulation

1992 ◽  
Vol 29 (6) ◽  
pp. 1087-1094 ◽  
Author(s):  
Chenmin Ma ◽  
Tomasz Hueckel
Keyword(s):  
Mass Transfer ◽  
Radioactive Waste ◽  
Heat Source ◽  
Pore Pressure ◽  
Adsorbed Water ◽  
Bulk Water ◽  
Excess Pore Pressure ◽  
Heat Output ◽  
Transfer Model ◽  
Excess Pore

Some effects of temperature increase due to the emplacement of radioactive waste on the mechanical and hydraulic behavior of saturated clays are studied numerically. A mass-transfer model is adopted which simulates a possible degeneration of adsorbed water into bulk water at temperatures up to 150 °C. In contrast with a previous paper by the authors the heat output decreases with time to realistically simulate the effect of nuclear waste. Numerical results show that in the vicinity of the line heat source, a much lower value of excess pore pressure and faster propagation of the excess pore-pressure front are obtained because of the substantial increase in permeability arising from the adsorbed water degeneration at elevated temperatures. Moreover, the adsorbed water degeneration accelerates the water flow around the heat source. It is also concluded that over a long term the thermally induced degeneration of absorbed water into bulk water mitigates the possibility of thermal failure of clays surrounding the heat source. Key words : heating, adsorbed water, bulk water, adsorbed water degeneration (mass transfer), permeability, specific discharge, pore pressure.

Two-Phase Flow Heat and Mass Transfer Model Construction and Experiment Study of the Fuel Evaporation Progress

2012 ◽  
Vol 614-615 ◽  
pp. 174-180
Author(s):  
Bo Yun Liu ◽  
Jin Yun Pu ◽  
Xiang Lie Yi
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Two Phase Flow ◽  
Time Dependent ◽  
Transfer Model ◽  
Phase Flow ◽  
Two Phase ◽  
Dependent Behavior ◽  
Mass Evaporation ◽  
Hot Surface

As for the time-dependent behavior of the fuel heat and mass evaporation transfer progress on hot surface,consider the convective mass transfer and heat transfer, the liquid-gas two-phase flow of continuous heat transfer model was studied. By the dimensionless transform, the time-dependent behavior of the concentration distribution and the temperature field was obtained. The result of n-Heptanes evaporation transfer progress on hot surface experiment is consistent with the academic model.

scholarly journals Modelling of Heat and Mass Transfer for Wire-Based Additive Manufacturing Using Electric Arc and Concentrated Sources of Energy

2018 ◽  
Vol 7 (4.38) ◽  
pp. 741
Author(s):  
Dmitriy Trushnikov ◽  
Anatoly Perminov ◽  
Shengyong Pang ◽  
K. P. Karunakaran ◽  
Vladimir Belenkiy ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Phase Transitions ◽  
Additive Manufacturing ◽  
Heat Source ◽  
Heat And Mass Transfer ◽  
Initial Temperature ◽  
Fluid Motion ◽  
Density Variation ◽  
Phase Region ◽  
Two Phase

The paper presents a model developed by the authors and aimed to describe heat and mass transfer during wire-based additive manufacturing, when electron beam, plasma or arc are used as energy sources in case of non-consumable electrode welding. The model describes non-stationary and non-equilibrium conjugated processes of heat and mass transfer in free-surface liquid metal. The solution of differential equations of viscous fluid motion (Navier-Stokes), with convective terms and at laminar flow, has become the model base. Melting and crystallization of the metal is recognized by heat release in a two-phase region. The material density variation during phase transitions of the first and the second order can be described by introducing a certain dependence on temperature. The model is able to consider the use of preliminary and additional induction heating by changing the initial temperature and establishing an additional distributed bulk heat source. Variables for the simulation of heat and mass transfer during additive formation are the intensity and type of the heat source, the plate initial temperature, the power density distribution, the intensity of the additional bulk heating, the dependence of material thermal and physical characteristics on temperature, the characteristics of the phase transitions, the motion velocity of the heat source, the rate of wire feeding. 

Study Of Nucleation And Growth Ev Al-Zn Alloys Using TEM

1993 ◽  
Vol 321 ◽  
Author(s):  
G. Sundar ◽  
E. A. Kenik ◽  
J. J. Hoyt ◽  
S. Spooner
Keyword(s):  
Completion Time ◽  
Nucleation And Growth ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Initial Value ◽  
Two Phase ◽  
Transmission Electron ◽  
Time Required ◽  
Zn Alloys

ABSTRACTNucleation and growth studies were conducted on Al-Zn alloys at several temperatures using transmission electron Microscopy (TEM) with an in-situ furnace. The value of the critical undercooling was established by noting the lowest temperature at which precipitates were no longer observed, following a quench into the two-phase metastable region. These results were compared with the Langer-Schwartz Model of nucleation and growth in which it is predicted that the half-completion time (i.e, the time required for the supersaturation to reach half its initial value) diverges for initial supersaturations which are higher than those predicted by the classical nucleation theory.

Heat Transfer Modeling and Application of Gas-Liquid Two-Phase Flow in Partially-Buried Pipeline

2013 ◽  
Author(s):  
Kai Wang ◽  
Qingping Li
Keyword(s):  
Heat Transfer ◽  
Linear Models ◽  
Temperature Drop ◽  
Transfer Model ◽  
Buried Pipeline ◽  
Two Phase ◽  
Gas Field ◽  
Corrosion Resistant ◽  
Heat Transfer Modeling ◽  
Corrosion Resistant Alloy

For the deepwater partially-buried pipeline transporting wet natural gas, a mechanistic heat transfer model is developed, and the temperature profile behaviors and corrosion resistant alloy (CRA) length of deepwater pipelines of Liwan3-1 gas field are studied by numerical simulation. The result shows that for a critical temperature of 23 °C, all production flowlines should be used CRA, and the CRA length of the tieback pipeline is recommended to be 1.5 km. There are significant differences of temperature drop between the mechanistic and linear models.

Using an improved 1D boundary layer model with CFD for flux prediction in gas-sparged tubular membrane ultrafiltration

2005 ◽  
Vol 51 (6-7) ◽  
pp. 69-76 ◽  
Author(s):  
S.R. Smith ◽  
T. Taha ◽  
Z.F. Cui
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Shear Stress ◽  
Porous Wall ◽  
Transfer Model ◽  
Layer Model ◽  
Two Phase ◽  
Flow Process ◽  
Tubular Membrane ◽  
Boundary Layer Model

Tubular membrane ultrafiltration and microfiltration are important industrial separation and concentration processes. Process optimisation requires reduction of membrane build-up. Gas slug introduction has been shown to be a useful approach for flux enhancement. However, process quantification is required for design and optimisation. In this work we employ a non-porous wall CFD model to quantify hydrodynamics in the two-phase slug flow process. Mass transfer is subsequently quantified from wall shear stress, which was determined from the CFD. The mass transfer model is an improved one-dimensional boundary layer model, which empirically incorporates effects of wall suction and analytically includes edge effects for circular conduits. Predicted shear stress profiles are in agreement with experimental results and flux estimates prove more reliable than that from previous models. Previous models ignored suction effects and employed less rigorous fluid property inclusion, which ultimately led to under-predictive flux estimates. The presented model offers reliable process design and optimisation criteria for gas-sparged tubular membrane ultrafiltration.

Instabilities and bifurcation of non-equilibrium two-phase flows

1997 ◽  
Vol 348 ◽  
pp. 1-28 ◽  
Author(s):  
STEPHAN ADAM ◽  
GÜNTER H. SCHNERR
Keyword(s):  
Equilibrium Phase ◽  
Practical Interest ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Droplet Growth ◽  
Sudden Increase ◽  
Pressure Amplitude ◽  
Two Phase ◽  
Supersonic Wind Tunnel ◽  
Non Equilibrium

New instabilites of unsteady transonic flows with non-equilibrium phase transition are presented including unsymmetric flow patterns with moving oblique shock systems in supersonic nozzles with perfectly symmetric shapes. The phenomena were first detected when performing experiments in our supersonic wind tunnel with atmospheric supply and could be perfectly reproduced by numerical simulations based on the Euler equations, i.e. neglecting the viscosity of the fluid. The formation of the liquid phase is modelled using the classical nucleation theory for the steady state together with the Hertz–Knudsen droplet growth law and yields qualitatively and quantitatively excellent agreement with experiments in the unsteady flow regime with high-frequency oscillations including the unstable transient change of the structure from symmetric to unsymmetric flow.For engineering applications the sudden increase or decrease of the frequency by a factor 2 or more and of the pressure amplitude at the bifurcation limits is of immediate practical interest, e.g. for flutter excitation of turbomachinery blading.

Numerical Sensitivity Study and Calibration of Non-Equilibrium Wet Steam Model

2013 ◽  
Author(s):  
F. J. Moraga ◽  
L. Wang ◽  
W.-M. Ren
Keyword(s):  
Droplet Diameter ◽  
Sensitivity Study ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Transfer Model ◽  
Wet Steam ◽  
Cfd Simulations ◽  
Pressure Profiles ◽  
Non Equilibrium

Comparisons between one- and two-dimensional experiments and non-equilibrium wet steam CFD simulations are conducted paying attention not only to pressure profiles and wetness but also to the more difficult to match droplet diameter. To achieve the objective of optimizing the match of data the heat transfer model between the droplet and its surrounding vapor proposed by Young and the corrections to classical nucleation theory proposed by Moore and popularized by Gerber are adopted. It is found that the proposed models produce a better agreement with droplet diameter, without affecting the overall quality of the predictions for other quantities.

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