Download or read book Modeling Primary Atomization of Liquid Fuels Using a Multiphase DNS LES Approach written by and published by . This book was released on 2016 with total page 2 pages. Available in PDF, EPUB and Kindle. Book excerpt: As part of a Laboratory Directed Research and Development project, we are developing a modeling-and-simulation capability to study fuel direct injection in automotive engines. Predicting mixing and combustion at realistic conditions remains a challenging objective of energy science. And it is a research priority in Sandia's mission-critical area of energy security, being also relevant to many flows in defense and climate. High-performance computing applied to this non-linear multi-scale problem is key to engine calculations with increased scientific reliability.
Download or read book Two Phase Flow for Automotive and Power Generation Sectors written by Kaushik Saha and published by Springer. This book was released on 2018-11-03 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the two-phase flow problems relevant in the automotive and power generation sectors. It includes fundamental studies on liquid–gas two-phase interactions, nucleate and film boiling, condensation, cavitation, suspension flows as well as the latest developments in the field of two-phase problems pertaining to power generation systems. It also discusses the latest analytical, numerical and experimental techniques for investigating the role of two-phase flows in performance analysis of devices like combustion engines, gas turbines, nuclear reactors and fuel cells. The wide scope of applications of this topic makes this book of interest to researchers and professionals alike.
Download or read book A Stable and Conservative Framework for Detailed Numerical Simulation of Primary Atomization written by Vincent Henri Marie Le Chenadec and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Energy conversion devices often rely on the combustion of high energy-density liquid fuel to meet weight and volume restrictions. The efficiency of the conversion and the emission of harmful pollutants depend directly on the mixing of the fuel and oxidizer, which itself results from a cascade of mechanisms initiated by the atomization of a coherent liquid stream. Despite existing investigations, the effects of nozzle design, surface tension, turbulence, and cavitation on atomizer performance are still poorly understood. The challenges found in experimental studies caused by the multi-scale and multi-physics aspects of such flows have motivated the development of numerical strategies to simulate the atomization process. In the direct numerical simulation approach considered in this work, the physics of the flow are all solved for directly. In the presence of complex topologies, the underlying equations are stiff, and, therefore, the development and improvement of numerical methods has been an area of active research. Among algorithms that have emerged, sharp interface methods including Volume-of-Fluid and Level Set have been shown to give reasonable performance. Applications of these methods to study primary atomization of turbulent jets have been documented, but the rare convergence studies available show strong grid dependence, suggesting the need for further developments. The present work focuses on two novel developments: an unsplit Volume-of-Fluid interface capturing algorithm designed to improve conservation on arbitrary grids, and a robust flow solver for incompressible Navier-Stokes equations in two-phase flows involving large density ratios. The resulting approach is shown to be stable and second order accurate. The framework is then assessed in a set of validation cases. In particular, the effect of mesh resolution is studied, and the ability of the method to accurately retain under-resolved structures is shown. Finally, computations of a large scale atomizer for varying operating conditions are presented. The excellent computational efficiency of the algorithm motivates the use of such a framework for simulating industrially relevant configurations.
Download or read book Modeling and Simulation of Turbulent Mixing and Reaction written by Daniel Livescu and published by Springer Nature. This book was released on 2020-02-19 with total page 273 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights recent research advances in the area of turbulent flows from both industry and academia for applications in the area of Aerospace and Mechanical engineering. Contributions include modeling, simulations and experiments meant for researchers, professionals and students in the area.
Download or read book Advancement of Numerical Methods for Simulating Primary Atomization written by Robert Michael Chiodi and published by . This book was released on 2020 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiphase flows are ubiquitous in natural and engineered systems and occur over scales ranging many orders of magnitude, from the movement of the ocean to the flow of blood through a capillary. In each case, the interface between the phases plays a key role in the dynamics of the flow. In this dissertation, I will detail the development of novel numerical methods for accurately and efficiently tracking the interface in simulations of multiphase flows, specifically focusing on flow configurations involving large density ratios, high shear at the interface, and liquid structures that span orders of magnitude in size. One specific instance where this occurs is during primary atomization, where a large liquid structure breaks up into smaller, more stable structures. This important class of flows is present in many different industries that currently employ over 2.5 million people. Enabling more accurate simulation of primary atomization is a central motivation of my work. To this end, I present significant improvements to the state-of-the-art for both level-set and volume of fluid methods. First, in the context of the conservative level-set method, the solution of the reinitialization equation is improved to drastically reduce the amount of error introduced. This reduction in error also leads to better volume conservation properties, especially for the under-resolved structures commonly created during atomization simulations. I then go on to detail improvements to geometric volume of fluid methods, which are capable of discretely conserving phase volumes at any level of resolution. For advecting the phase volumes, I provide a systematic approach to geometric advection on unstructured meshes that leads to significant gains in speed with no sacrifice in solution accuracy. On the topic of interface reconstruction, a novel multi-plane strategy capable of capturing arbitrarily-thin sub-grid scale films is given. To improve the performance of these methods, a general, robust, and efficient polyhedron intersection algorithm has also been developed and will be discussed in detail. In all cases, the work is placed in the context of the current state-of-the-art through direct comparison to published results. A major portion of my work has also involved creating the open-source Interface Reconstruction Library, which provides implementations of modern algorithms used in volume of fluid methods, including those presented in this dissertation. This library, along with the presented methods, has been applied to simulate large-scale, complicated, and realistic atomizing flows. In particular, they have driven the near-field simulation capabilities for an Office of Naval Research Multidisciplinary Research Initiative (MURI) on active spray control, been used to study the dynamics of a compressible liquid jet in cross-flow configuration for the Air Force Research Laboratory, and been employed by Los Alamos National Laboratory to simulate the injection of liquid metal in metal casting simulations.
Download or read book 1D and Multi D Modeling Techniques for IC Engine Simulation written by Angelo Onorati and published by SAE International. This book was released on 2020-04-06 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt: 1D and Multi-D Modeling Techniques for IC Engine Simulation provides a description of the most significant and recent achievements in the field of 1D engine simulation models and coupled 1D-3D modeling techniques, including 0D combustion models, quasi-3D methods and some 3D model applications.
Download or read book Droplets and Sprays written by Sergei Sazhin and published by Springer. This book was released on 2014-05-19 with total page 345 pages. Available in PDF, EPUB and Kindle. Book excerpt: Providing a clear and systematic description of droplets and spray dynamic models, this book maximises reader insight into the underlying physics of the processes involved, outlines the development of new physical and mathematical models and broadens understanding of interactions between the complex physical processes which take place in sprays. Complementing approaches based on the direct application of computational fluid dynamics (CFD), Droplets and Sprays treats both theoretical and practical aspects of internal combustion engine process such as the direct injection of liquid fuel, subcritical heating and evaporation. Including case studies that illustrate the approaches relevance to automotive applications, it is also anticipated that the described models can find use in other areas such as in medicine and environmental science.
Download or read book Experiments and Numerical Simulations of Turbulent Combustion of Diluted Sprays written by Bart Merci and published by Springer Science & Business Media. This book was released on 2014-03-27 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reflects the results of the 2nd and 3rd International Workshops on Turbulent Spray Combustion. The focus is on progress in experiments and numerical simulations for two-phase flows, with emphasis on spray combustion. Knowledge of the dominant phenomena and their interactions allows development of predictive models and their use in combustor and gas turbine design. Experts and young researchers present the state-of-the-art results, report on the latest developments and exchange ideas in the areas of experiments, modelling and simulation of reactive multiphase flows. The first chapter reflects on flame structure, auto-ignition and atomization with reference to well-characterized burners, to be implemented by modellers with relative ease. The second chapter presents an overview of first simulation results on target test cases, developed at the occasion of the 1st International Workshop on Turbulent Spray Combustion. In the third chapter, evaporation rate modelling aspects are covered, while the fourth chapter deals with evaporation effects in the context of flamelet models. In chapter five, LES simulation results are discussed for variable fuel and mass loading. The final chapter discusses PDF modelling of turbulent spray combustion. In short, the contributions in this book are highly valuable for the research community in this field, providing in-depth insight into some of the many aspects of dilute turbulent spray combustion.
Download or read book LES Combined with Statistical Models of Spray Formation Closely to Air blast Atomizer written by Tian Deng and published by . This book was released on 2011 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis introduced an extension to stochastic approach for simulation of air-blast atomization closely to injector. This approach was previously proposed in publications of Gorokhovski with his PHD students. Our extension of this approach is as follows. In the framework of LES approach, the contribution of primary atomization zone is simulated as an immersed solid body with stochastic structure. The last one is defined by stochastic simulation of position-and-curvature of interface between the liquid and the gas. As it was done previously in this approach, the simulation of the interface position was based on statistical universalities of fragmentation under scaling symmetry. Additionally to this, we simulate the outwards normal to the interface, assuming its stochastic relaxation to isotropy along with propagation of spray in the down-stream direction. In this approach, the statistics of immersed body force plays role of boundary condition for LES velocity field, as well as for production of primary blobs, which are then tracked in the Lagrangian way. In this thesis, the inter-particle collisions in the primary atomisation zone are accounted also by analogy with standard kinetic approach for the ideal gas. The closure is proposed for the statistical temperature of droplets. The approach was assessed by comparison with measurements of Hong in his PHD. The results of computation showed that predicted statistics of the velocity and of the size in the spray at different distances from the center plane, at different distances from the nozzle orifice, at different inlet conditions (different gas velocity at constant gas-to-liquid momentum ratio, different gas-to-liquid momentum ratio) are relatively close to measurements. Besides, the specific role of recirculation zone in front of the liquid core was emphasized in the flapping of the liquid core and in the droplets production.
Download or read book Handbook of Atomization and Sprays written by Nasser Ashgriz and published by Springer Science & Business Media. This book was released on 2011-02-18 with total page 922 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atomization and sprays are used in a wide range of industries: mechanical, chemical, aerospace, and civil engineering; material science and metallurgy; food; pharmaceutical, forestry, environmental protection; medicine; agriculture; meteorology and others. Some specific applications are spray combustion in furnaces, gas turbines and rockets, spray drying and cooling, air conditioning, powdered metallurgy, spray painting and coating, inhalation therapy, and many others. The Handbook of Atomization and Sprays will bring together the fundamental and applied material from all fields into one comprehensive source. Subject areas included in the reference are droplets, theoretical models and numerical simulations, phase Doppler particle analysis, applications, devices and more.
Download or read book Coarse Grained Simulation and Turbulent Mixing written by Fenando F. Grinstein and published by Cambridge University Press. This book was released on 2016-06-30 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reviews our current understanding of the subject. For graduate students and researchers in computational fluid dynamics and turbulence.
Download or read book OpenFOAM written by J. Miguel Nóbrega and published by Springer. This book was released on 2019-01-24 with total page 527 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains selected papers of the 11th OpenFOAM® Workshop that was held in Guimarães, Portugal, June 26 - 30, 2016. The 11th OpenFOAM® Workshop had more than 140 technical/scientific presentations and 30 courses, and was attended by circa 300 individuals, representing 180 institutions and 30 countries, from all continents. The OpenFOAM® Workshop provided a forum for researchers, industrial users, software developers, consultants and academics working with OpenFOAM® technology. The central part of the Workshop was the two-day conference, where presentations and posters on industrial applications and academic research were shown. OpenFOAM® (Open Source Field Operation and Manipulation) is a free, open source computational toolbox that has a larger user base across most areas of engineering and science, from both commercial and academic organizations. As a technology, OpenFOAM® provides an extensive range of features to solve anything from complex fluid flows involving chemical reactions, turbulence and heat transfer, to solid dynamics and electromagnetics, among several others. Additionally, the OpenFOAM technology offers complete freedom to customize and extend its functionalities.
Download or read book Fluid Mechanics at Interfaces 1 written by Roger Prudhomme and published by John Wiley & Sons. This book was released on 2022-03-04 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: Interfaces are present in most fluid mechanics problems. They not only denote phase separations and boundary conditions, but also thin flames and discontinuity waves. Fluid Mechanics at Interfaces 1 focuses on the science of interfaces, in particular, using various scientific methods of analysis relating to space, speed and time. Our investigation takes us from the microscopic or small scale (starting with molecular and nanoscopic scales) to the macroscopic (including meso and interstellar scales), and also explores the laws of interfaces (classical mechanics, quantum mechanics and relativistic mechanics). Chapter 1 examines the questions raised by modeling interfaces in the presence of one or more fluid phases. Chapter 2 discusses the action of turbulence in liquid–vapor flows that contain both small, dispersed bubbles as well as large bubbles, with heat exchanges at the interfaces. In addition, a new model is presented, using large eddy simulation (LES). Chapter 3 studies an original method for calculating the drag force and thermal transfers in flows around networks of spherical particles, while Chapter 4 focuses on the relationships between interfaces and critical fluids. Chapter 5 examines shearing, which causes anomalies in the Brownian motion of particles in strongly fluctuating near-critical mixtures, and Chapter 6 introduces basic concepts related to combustion interfaces, raising the question of the combustion of solids, before ending with a brief presentation of the Rankine–Hugoniot theory and a historical overview of the research carried out in the field of combustion.
Download or read book Multiphase Flow Handbook Second Edition written by Efstathios Michaelides and published by CRC Press. This book was released on 2016-10-26 with total page 1559 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Multiphase Flow Handbook, Second Edition is a thoroughly updated and reorganized revision of the late Clayton Crowe’s work, and provides a detailed look at the basic concepts and the wide range of applications in this important area of thermal/fluids engineering. Revised by the new editors, Efstathios E. (Stathis) Michaelides and John D. Schwarzkopf, the new Second Edition begins with two chapters covering fundamental concepts and methods that pertain to all the types and applications of multiphase flow. The remaining chapters cover the applications and engineering systems that are relevant to all the types of multiphase flow and heat transfer. The twenty-one chapters and several sections of the book include the basic science as well as the contemporary engineering and technological applications of multiphase flow in a comprehensive way that is easy to follow and be understood. The editors created a common set of nomenclature that is used throughout the book, allowing readers to easily compare fundamental theory with currently developing concepts and applications. With contributed chapters from sixty-two leading experts around the world, the Multiphase Flow Handbook, Second Edition is an essential reference for all researchers, academics and engineers working with complex thermal and fluid systems.
Download or read book Fluid Dynamics at Interfaces written by Wei Shyy and published by Cambridge University Press. This book was released on 1999-09-28 with total page 482 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book experts discuss research and applications in interfacial fluid dynamics.
Download or read book Adaptive and Convergent Methods for Large Eddy Simulation of Turbulent Combustion written by Colin Russell Heye and published by . This book was released on 2014 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the recent past, LES methodology has emerged as a viable tool for modeling turbulent combustion. LES computes the large scale mixing process accurately, thereby providing a better starting point for small-scale models that describe the combustion process. Significant effort has been made over past decades to improve accuracy and applicability of the LES approach to a wide range of flows, though the current conventions often lack consistency to the problems at hand. To this end, the two main objectives of this dissertation are to develop a dynamic transport equation-based combustion model for large- eddy simulation (LES) of turbulent spray combustion and to investigate grid- independent LES modeling for scalar mixing. Long-standing combustion modeling approaches have shown to be suc- cessful for a wide range of gas-phase flames, however, the assumptions required to derive these formulations are invalidated in the presence of liquid fuels and non-negligible evaporation rates. In the first part of this work, a novel ap- proach is developed to account for these evaporation effects and the resulting multi-regime combustion process. First, the mathematical formulation is de- rived and the numerical implementation in a low-Mach number computational solver is verified against one-dimensional and lab scale, both non-reacting and reacting spray-laden flows. In order to clarify the modeling requirements in LES for spray combustion applications, results from a suite of fully-resolved direct numerical simulations (DNS) of a spray laden planar jet flame are fil- tered at a range of length scales. LES results are then validated against two sets of experimental jet flames, one having a pilot and allowing for reduced chemistry modeling and the second requiring the use of detail chemistry with in situ tabulation to reduce the computational cost of the direct integration of a chemical mechanism. The conventional LES governing equations are derived from a low-pass filtering of the Navier-Stokes equations. In practice, the filter used to derive the LES governing equations is not formally defined and instead, it is assumed that the discretization of LES equations will implicitly act as a low-pass filter. The second part of this study investigates an alternative derivation of the LES governing equations that requires the formal definition of the filtering operator, known as explicitly filtered LES. It has been shown that decoupling the filter- ing operation from the underlying grid allows for the isolation of subfilter-scale modeling errors from numerical discretization errors. Specific to combustion modeling are the aggregate errors associated with modeling sub-filter distribu- tions of scalars that are transported by numerical impacted turbulent fields. Quantities of interest to commonly-used combustion models, including sub- filter scalar variance and filtered scalar dissipation rate, are investigated for both homogeneous and shear-driven turbulent mixing.
Download or read book Atomization Modeling in a Multiphase Flow Environment and Comparison with Experiments written by P. Y. Liang and published by . This book was released on 1990 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
