scholarly journals Experimental and Numerical Investigation of Phase Separation due to Multi-Component Mixing at High-Pressure Conditions

2017 ◽  
Author(s):  
Christoph Traxinger ◽  
Hagen Müller ◽  
Michael Pfitzner ◽  
Steffen Baab ◽  
Grazia Lamanna ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Separation ◽  
Numerical Simulations ◽  
A Priori ◽  
Two Phase ◽  
Separation Processes ◽  
Pure Nitrogen ◽  
Elastic Light Scattering ◽  
Large Eddy ◽  
High Pressure Injection

Experiments and numerical simulations were carried out in order to contribute to a better understanding and predic-tion of high-pressure injection into a gaseous environment. Specifically, the focus was put on the phase separation processes of an initially supercritical fluid due to the interaction with its surrounding. N-hexane was injected into a chamber filled with pure nitrogen at 5 MPa and 293 K and three different test cases were selected such that they cover regimes in which the thermodynamic non-idealities, in particular the effects that stem from the potential phase separation, are significant. Simultaneous shadowgraphy and elastic light scattering experiments were conducted to capture both the flow structure as well as the phase separation. In addition, large-eddy simulations with a vapor- liquid equilibrium model were performed. Both experimental and numerical results show phase formation for the cases, where the a-priori calculation predicts two-phase flow. Moreover, qualitative characteristics of the formation process agree well between experiments and numerical simulations and the transition behaviour from a dense-gasto a spray-like jet was captured by both.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4756

Understanding High-pressure Injection Primary Breakup by Using Large Eddy Simulation and X-ray Spray Imaging

MTZ worldwide ◽  
2017 ◽  
Vol 78 (5) ◽  
pp. 50-57 ◽  
Author(s):  
Junmei Shi ◽  
Pablo Lopez Aguado ◽  
Noureddine Guerrassi ◽  
Gavin Dober
Keyword(s):  
High Pressure ◽  
Large Eddy Simulation ◽  
X Ray ◽  
Eddy Simulation ◽  
Pressure Injection ◽  
Large Eddy ◽  
Primary Breakup ◽  
High Pressure Injection

A Comprehensive Thermodynamic Approach to Acoustic Cavitation Simulation in High-Pressure Injection Systems by a Conservative Homogeneous Two-Phase Barotropic Flow Model

2005 ◽  
Vol 128 (2) ◽  
pp. 434-445 ◽  
Author(s):  
Andrea E. Catania ◽  
Alessandro Ferrari ◽  
Michele Manno ◽  
Ezio Spessa
Keyword(s):  
High Pressure ◽  
Wave Propagation ◽  
Flow Model ◽  
Acoustic Cavitation ◽  
Injection System ◽  
Pure Liquid ◽  
Two Phase ◽  
Pressure Injection ◽  
Barotropic Flow ◽  
High Pressure Injection

A general conservative numerical model for the simulation of transmission-line unsteady fluid dynamics has been developed and applied to high-pressure injection systems. A comprehensive thermodynamic approach for modeling acoustic cavitation, i.e., cavitation induced by wave propagation, was proposed on the basis of a conservative homogeneous two-phase barotropic flow model of a pure liquid, its vapor, and a gas, both dissolved and undissolved. A physically consistent sound speed equation was set in a closed analytical form of wide application. For the pure-liquid flow simulation outside the cavitation regions, or in the absence of these, temperature variations due to compressibility effects were taken into account, for the first time in injection system simulation, through a thermodynamic relation derived from the energy equation. Nevertheless, in the cavitating regions, an isothermal flow was retained consistently with negligible macroscopic thermal effects due to vaporization or condensation, because of the tiny amounts of liquid involved. A novel implicit, conservative, one-step, symmetrical, and trapezoidal scheme of second-order accuracy was employed to solve the partial differential equations governing the pipe flow. It can also be enhanced at a high-resolution level. The numerical model was applied to wave propagation and cavitation simulation in a high-pressure injection system of the pump-line-nozzle type for light and medium duty vehicles. The system was relevant to model assessment because, at part loads, it presented cavitating flow conditions that can be considered as severe, at least for a diesel injection system. The predicted time histories of pressure at two pipe locations and of injector needle lift were compared to experimental results, substantiating the validity and robustness of the developed conservative model in simulating acoustic cavitation inception and desinence with great accuracy degree. Cavitation transients and the flow discontinuities induced by them were numerically predicted and analyzed.

Euler-Euler Large-Eddy Simulation Approach for Non Isothermal Particle-Laden Turbulent Jet

2008 ◽  
Author(s):  
Enrica Masi ◽  
Benoiˆt Be´dat ◽  
Mathieu Moreau ◽  
Olivier Simonin
Keyword(s):  
Large Eddy Simulation ◽  
Particle Temperature ◽  
Turbulent Transport ◽  
A Priori ◽  
Particle Simulation ◽  
Dispersed Phase ◽  
Two Phase Flows ◽  
Two Phase ◽  
Eddy Simulation ◽  
Large Eddy

This paper presents an Euler-Euler Large-Eddy Simulation (LES) approach for the numerical modeling of non isothermal dispersed turbulent two-phase flows. The proposed approach is presented and validated by a priori tests from an Euler-Lagrange database, provided using discrete particle simulation (DPS) of the particle phase coupled with direct numerical simulation (DNS) of the turbulent carrier flow, in a non isothermal particle-laden temporal jet configuration. A statistical approach, the Mesoscopic Eulerian Formalism (MEF) [Fe´vrier et al., J. Fluid Mech., 2005, vol. 533, pp. 1–46], is used to write local and instantaneous Eulerian equations for the dispersed phase and then, by spatial averaging, to derive the LES equations governing the filtered variables. In this work, the MEF approach is extended to scalar variables transported by the particles in order to develop LES for reactive turbulent dispersed two-phase flows with mass and heat turbulent transport. This approach leads to separate the instantaneous particle temperature distribution in a Mesoscopic Eulerian field, shared by all the particles, and a Random Uncorrelated distribution which may be characterized in terms of Eulerian fields of particle moments such as the uncorrelated temperature variance. In this paper, the DPS-DNS numerical database is presented, LES Eulerian equations for the dispersed phase are derived in the frame of the Mesoscopic approach and models for the unresolved subgrid and random uncorrelated terms are proposed and a priori tested using the DPS-DNS database.

Hierarchical Structuring in Block Copolymer Nanocomposites through Two Phase-Separation Processes Operating on Different Time Scales

2013 ◽  
Vol 23 (34) ◽  
pp. 4215-4226 ◽  
Author(s):  
Elina Ploshnik ◽  
Karol M. Langner ◽  
Amit Halevi ◽  
Meirav Ben-Lulu ◽  
Axel H. E. Müller ◽  
...  
Keyword(s):  
Phase Separation ◽  
Block Copolymer ◽  
Time Scales ◽  
Two Phase ◽  
Separation Processes ◽  
Hierarchical Structuring ◽  
Different Time Scales

Implicit Numerical Model of a High-Pressure Injection System

1992 ◽  
Vol 114 (3) ◽  
pp. 534-543 ◽  
Author(s):  
A. E. Catania ◽  
C. Dongiovanni ◽  
A. Mittica
Keyword(s):  
High Pressure ◽  
Differential Equations ◽  
Gaussian Elimination ◽  
Injection Pressure ◽  
Injection System ◽  
Algebraic Equations ◽  
Two Phase ◽  
Boundary Shear ◽  
Pressure Injection ◽  
High Pressure Injection

An implicit finite-difference numerical method has been developed and applied to the simulation of unsteady flow phenomena in a high-pressure injection system. A first-order one-step BSBT (backward space, backward time) scheme was used to obtain the difference analogue of the one-dimensional, elemental-volume averaged, partial differential equations governing the pressure-pipe flow. Second and higher-order implicit difference representations were employed for the ordinary differential equations simulating the pump and injector dynamics. The resultant nonlinear algebraic equations were solved by the Newton-Raphson method and a fast modified version of the Gaussian elimination procedure was used to solve the linearized equations. This was an extension of the Thomas solver to a multidiagonal system of algebraic equations. A compact, efficient and stable numerical algorithm was so obtained. The mathematical model takes into account the compressibility of the liquid fuel, the boundary shear, and also includes the simulation of possible cavitation occurrence at one or multiple locations in the injection system. No artificial viscosity has to be added to the solution in the vicinity of discontinuities induced by cavitation in the flow properties. The cavitation simulation is based on a simple mixture model of transient two-phase flow in pipes and can incorporate the effects of gaseous cavitation occurrence. Experimental values of the flow coefficients were used for the pump and injector and, for the latter, the dependence of the discharge coefficients on the needle lift and injection pressure was also taken into account. The model was tested and validated by comparing the numerical results with those of experiments carried out at the Fiat Research Center on a diesel-engine inline injection system, with a jerk-pump and an orifice type nozzle-injector.

The Interaction of Spinning Liquid Film With Swirling Gas in Cylindrical Vessel—Experiments and Numerical Simulations

1998 ◽  
Vol 120 (4) ◽  
pp. 690-697
Author(s):  
Avi Birk ◽  
James DeSpirito
Keyword(s):  
High Pressure ◽  
Liquid Film ◽  
Numerical Simulations ◽  
Liquid Flow ◽  
Gas Injection ◽  
Test Chamber ◽  
Cylindrical Vessel ◽  
System Component ◽  
Two Phase ◽  
Flow Visualizations

Experimental flow visualizations and numerical simulations of the interaction of a spinning liquid film with a swirling gas in a cylindrical vessel are reported. A gas/liquid flow that simulates the high-pressure conditions of combustion was successfully visualized in a transparent test chamber. The test chamber was a mockup of a liquid propellant gun ignition system component called the hydrodynamically-stabilized combustor. Water-glycerol mixtures were used for the liquid, and ballistically compressed helium-nitrogen was used for the gas. The liquid is injected tangentially along the cylindrical test chamber wall where it spreads as a spinning film. The gas is then injected tangentially and interacts with the liquid. The flows were insensitive to the tilt angle of the test chamber and only mildly sensitive to the liquid viscosity. Liquid entrainment by the gas and subsequent atomization occurs promptly (within 2 ms) after the onset of gas injection, and the flow in the test chamber vent passage is a swirling, transonic, two-phase flow. Two types of three-dimensional simulations of the liquid and gas injection into the test chamber were performed using the CRAFT Navier-Stokes code. The first type was of the initial liquid flow only. The second type was of the high-pressure gas injection into the chamber, with the liquid initialized in an annulus around the chamber surface with a swirl velocity. The numerical simulations were successful in capturing the primary characteristics of the flow phenomena observed in the experimental flow visualizations. This included yielding the observed liquid flow patterns before gas injection and capturing the cellular structure observed after gas injection.

Numerical simulation of phase separation and a priori two-phase LES filtering

2008 ◽  
Vol 37 (7) ◽  
pp. 898-906 ◽  
Author(s):  
S. Vincent ◽  
J. Larocque ◽  
D. Lacanette ◽  
A. Toutant ◽  
P. Lubin ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Phase Separation ◽  
A Priori ◽  
Two Phase

scholarly journals A priori filtering and LES modeling of turbulent two-phase flows application to phase separation

2018 ◽  
Vol 176 ◽  
pp. 245-259 ◽  
Author(s):  
S. Vincent ◽  
M. Tavares ◽  
S. Fleau ◽  
S. Mimouni ◽  
M. Ould-Rouiss ◽  
...  
Keyword(s):  
Phase Separation ◽  
A Priori ◽  
Two Phase Flows ◽  
Two Phase
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