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Author: Bejoy Mandumpala devassy
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
In internal combustion engines, the liquid fuel injection is an essential step for the air/fuel mixture preparation and the combustion process. Indeed, the structure of the liquid jet coming out from the injector plays a key role in the proper mixing of the fuel with the gas in the combustion chamber. The present work focuses on the liquid jet atomization phenomena under Diesel engine conditions. Under these conditions, liquid jet morphology includes a separate liquid phase (i.e. a liquid core) and a dispersed liquid phase (i.e. a spray). This manuscript describes the development stages of a new atomization model, for a high speed liquid jet, based on an eulerian two-phase approach. The atomization phenomenon is modeled by defining different surface density equations, for the liquid core and the spray droplets. This new model has been coupled with a turbulent two-phase system of equations of Baer-Nunziato type. The process of ligament breakup and its subsequent breakup into droplets are handled with respect to available experiments and high fidelity numerical simulations. In the dense region of the liquid jet, the atomization is modeled as a dispersion process due to the turbulent stretching of the interface, from the side of liquid in addition to the gas side. Different academic test cases have been performed in order to verify the numerical implementation of the model in the IFP-C3D software. Finally, the model is validated with the recently published DNS results under typical conditions of direct injection Diesel engines.
Author: Bejoy Mandumpala devassy
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
In internal combustion engines, the liquid fuel injection is an essential step for the air/fuel mixture preparation and the combustion process. Indeed, the structure of the liquid jet coming out from the injector plays a key role in the proper mixing of the fuel with the gas in the combustion chamber. The present work focuses on the liquid jet atomization phenomena under Diesel engine conditions. Under these conditions, liquid jet morphology includes a separate liquid phase (i.e. a liquid core) and a dispersed liquid phase (i.e. a spray). This manuscript describes the development stages of a new atomization model, for a high speed liquid jet, based on an eulerian two-phase approach. The atomization phenomenon is modeled by defining different surface density equations, for the liquid core and the spray droplets. This new model has been coupled with a turbulent two-phase system of equations of Baer-Nunziato type. The process of ligament breakup and its subsequent breakup into droplets are handled with respect to available experiments and high fidelity numerical simulations. In the dense region of the liquid jet, the atomization is modeled as a dispersion process due to the turbulent stretching of the interface, from the side of liquid in addition to the gas side. Different academic test cases have been performed in order to verify the numerical implementation of the model in the IFP-C3D software. Finally, the model is validated with the recently published DNS results under typical conditions of direct injection Diesel engines.
Author: Wei Ning
Publisher:
ISBN:
Category :
Languages : en
Pages : 212
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Author: Novid Beheshti
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722127954
Category :
Languages : en
Pages : 56
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Book Description
The tracking of free surfaces between liquid and gas phases and analysis of the interfacial phenomena between the two during the atomization and breakup process of a liquid fuel jet is modeled. Numerical modeling of liquid-jet atomization requires the resolution of different conservation equations. Detailed formulation and validation are presented for the confined dam broken problem, the water surface problem, the single droplet problem, a jet breakup problem, and the liquid column instability problem. Seung, S. P. and Chen, C. P. and Ziebarth, John P. Unspecified Center...
Author: Hossam Said Mohamed Aly
Publisher: Penerbit UTM Press
ISBN: 9835209219
Category : Atomization
Languages : en
Pages : 5
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Book Description
Issues regarding spray and atomization of liquid that occur in many industrial applications are crucial for many combustion systems. However, a full understanding of such process is still lacking. In order to have a better understanding of the phenomena, numerical modeling of sprays would be a valuable tool in designing and assessing the performance of the combustion systems. Most multiphase computational fluid dynamics (CFD) models are classified into two categories: Eulerian–Lagrangian and Eulerian–Eulerian models. Although Eulerian–Lagrangian models are traditionally the most common choice for modeling spray problems, they include a large number of empirical sub–models and hence are very sensitive to fine tuning and rely heavily on the experiments. In this book, a newly developed mathematical model for calculating droplet break–up frequency based on both drag and turbulence induced fragmentation stresses is presented. The droplet break–up model was introduced into a CFD methodology based on the Eulerian–Eulerian approach, in which the mass and momentum conservation equations are solved for both phases. The CFD solver couples the population balance equation along with Navier–Stokes equations for tracking droplet diameters. The proposed mathematical model has the advantage of taking into account the effects of drag and turbulence stresses on the atomization process while abandoning the common disadvantages of current Lagrangian models. Numerical simulations were performed to model a coaxial air–blast atomizer using both the traditional Lagrangian model and the new Eulerian model.
Author: Manuel García-Villalba
Publisher: Springer Nature
ISBN: 3030428222
Category : Technology & Engineering
Languages : en
Pages : 478
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Book Description
This book gathers the proceedings of the 12th instalment in the bi-annual Workshop series on Direct and Large Eddy Simulation (DLES), which began in 1994 and focuses on modern techniques used to simulate turbulent flows based on the partial or full resolution of the instantaneous turbulent flow structure. With the rapidly expanding capacities of modern computers, this approach has attracted more and more interest over the years and will undoubtedly be further enhanced and applied in the future. Hybrid modelling techniques based on a combination of LES and RANS approaches also fall into this category and are covered as well. The goal of the Workshop was to share the state of the art in DNS, LES and related techniques for the computation and modelling of turbulent and transitional flows. The respective papers highlight the latest advances in the prediction, understanding and control of turbulent flows in academic and industrial applications.
Author: Sina Ghods
Publisher:
ISBN:
Category : Atomization
Languages : en
Pages : 86
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Book Description
The atomization of a liquid jet by a high speed cross-flowing gas has many applications such as gas turbines and augmentors. The mechanisms by which the liquid jet initially breaks up, however, are not well understood. Experimental studies suggest the dependence of spray properties on operating conditions and nozzle geometry. Detailed numerical simulations can offer better understanding of the underlying physical mechanisms that lead to the breakup of the injected liquid jet. In this work, detailed numerical simulation results of turbulent liquid jets injected into turbulent gaseous cross flows for different density ratios is presented. A finite volume, balanced force fractional step flow solver to solve the Navier-Stokes equations is employed and coupled to a Refined Level Set Grid method to follow the phase interface. To enable the simulation of atomization of high density ratio fluids, we ensure discrete consistency between the solution of the conservative momentum equation and the level set based continuity equation by employing the Consistent Rescaled Momentum Transport (CRMT) method. The impact of different inflow jet boundary conditions on different jet properties including jet penetration is analyzed and results are compared to those obtained experimentally by Brown & McDonell(2006). In addition, instability analysis is performed to find the most dominant insta- bility mechanism that causes the liquid jet to breakup. Linear instability analysis is achieved using linear theories for Rayleigh-Taylor and Kelvin- Helmholtz instabilities and non-linear analysis is performed using our flow solver with different inflow jet boundary conditions.
Author: James H. Whitelaw
Publisher: Springer Science & Business Media
ISBN: 3662105020
Category : Technology & Engineering
Languages : en
Pages : 494
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Book Description
This is the second book edited with a selection of papers from the two-yearly THIESEL Conference on Thermo- and Fluid Dynamic Processes in Diesel Engines, organised by CMT-Mvtores Termicos of the Universidad Po/itecnica de Valencia, Spain. This volume includes versions of papers selected from those presented at the THIESEL 2002 Conference th held on lOth to 13 September 2002. We hope it will be the second volume of a long series reflecting the quality of the THIESEL Conference. This year, the papers are grouped in six main thematic areas: State of the Art and Prospective, Injection Systems and Spray Formation, Combustion and Emissions, Engine Modelling, Alternative Combustion Concepts and Experimental Techniques. The actual conference covered a wider scope of topics, including Air Management and Fuels for Diesel Engines and a couple of papers included reflect this variety. However, the selection of papers published here represents the most current preoccupations of Diesel engine designers, namely how to improve the combustion process using new injection strategies and alternative concepts such as the Homogeneous Charge Combustion Ignition.
Author: Andreas Dillmann
Publisher: Springer Science & Business Media
ISBN: 3642142435
Category : Technology & Engineering
Languages : en
Pages : 629
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Book Description
th This volume contains the papers presented at the 16 DGLR/STAB-Symposium held at the Eurogress Aachen and organized by RWTH Aachen University, Germany, November, 3 - 4, 2008. STAB is the German Aerospace Aerodynamics Association, founded towards the end of the 1970's, whereas DGLR is the German Society for Aeronautics and Astronautics (Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal Oberth e.V.). The mission of STAB is to foster development and acceptance of the discipline “Aerodynamics” in Germany. One of its general guidelines is to concentrate resources and know-how in the involved institutions and to avoid duplication in research work as much as possible. Nowadays, this is more necessary than ever. The experience made in the past makes it easier now, to obtain new knowledge for solving today's and tomorrow's problems. STAB unites German scientists and engineers from universities, research-establishments and industry doing research and project work in numerical and experimental fluid mechanics and aerodynamics for aerospace and other applications. This has always been the basis of numerous common research activities sponsored by different funding agencies. Since 1986 the symposium has taken place at different locations in Germany every two years. In between STAB workshops regularly take place at the DLR in Göttingen.
Author: SH Chan
Publisher: Taylor & Francis
ISBN: 1351407007
Category : Technology & Engineering
Languages : en
Pages : 1862
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Book Description
This two-volume set presents the proceedings from the 8th International Symposium on Transport Phenomena in Combustion. There are more than 150 chapters that provide an extensive review of topics such as complete numerical simulation of combustion and heat transfer in furnaces and boilers, the interaction of combustion and heat transfer in porous media for low emission, high efficiency applications, industrial combustion technology, experimental and diagnostic methods and active combustion control, and fire research, internal combustion engine, Nox and soot emission.
