Numerical Modeling for Primary Atomization of Liquid Jets PDF Download
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Author: A. Przekwas
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: A. Przekwas
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
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: Yash Akhil Bhatt
Publisher:
ISBN:
Category : Fluid dynamics
Languages : en
Pages : 118
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Book Description
"Break-up and atomization characteristics of JetA liquid fuel were investigated numerically. The results have been compared to various experimental results to evaluate the accuracy of the numerical model. The CDF code ANSYS-CFX 12.0 was used to carry out the steady state analysis at different time scales. A comparison between the atomization characteristics of a pressure jet atomizer and an air-blast atomizer is shown."--Leaf iii.
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781719484084
Category :
Languages : en
Pages : 90
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Book Description
Recent studies indicate that turbulence behaviors within a liquid jet have considerable effect on the atomization process. Such turbulent flow phenomena are encountered in most practical applications of common liquid spray devices. This research aims to model the effects of turbulence occurring inside a cylindrical liquid jet to its atomization process. The two widely used atomization models Kelvin-Helmholtz (KH) instability of Reitz and the Taylor analogy breakup (TAB) of O'Rourke and Amsden portraying primary liquid jet disintegration and secondary droplet breakup, respectively, are examined. Additional terms are formulated and appropriately implemented into these two models to account for the turbulence effect. Results for the flow conditions examined in this study indicate that the turbulence terms are significant in comparison with other terms in the models. In the primary breakup regime, the turbulent liquid jet tends to break up into large drops while its intact core is slightly shorter than those without turbulence. In contrast, the secondary droplet breakup with the inside liquid turbulence consideration produces smaller drops. Computational results indicate that the proposed models provide predictions that agree reasonably well with available measured data. Trinh, H. P. Marshall Space Flight Center TURBULENCE EFFECTS; MATHEMATICAL MODELS; COMPUTATIONAL FLUID DYNAMICS; LIQUID ATOMIZATION; TURBULENT FLOW; JET FLOW; KELVIN-HELMHOLTZ INSTABILITY; DIRECT NUMERICAL SIMULATION; LARGE EDDY SIMULATION; DROP SIZE; SPRAYERS; TURBULENT JETS; DISINTEGRATION
Author: Frank-Olivier Albina
Publisher:
ISBN: 9783892206316
Category : Jets
Languages : de
Pages : 121
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Book Description
Author: Stéphane Vincent
Publisher: Springer Nature
ISBN: 3031092651
Category : Technology & Engineering
Languages : en
Pages : 314
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Book Description
The book provides basic and recent research insights concerning the small scale modeling and simulation of turbulent multi-phase flows. By small scale, it has to be understood that the grid size for the simulation is smaller than most of the physical time and space scales of the problem. Small scale modeling of multi-phase flows is a very popular topic since the capabilities of massively parallel computers allows to go deeper into the comprehension and characterization of realistic flow configurations and at the same time, many environmental and industrial applications are concerned such as nuclear industry, material processing, chemical reactors, engine design, ocean dynamics, pollution and erosion in rivers or on beaches. The work proposes a complete and exhaustive presentation of models and numerical methods devoted to small scale simulation of incompressible turbulent multi-phase flows from specialists of the research community. Attention has also been paid to promote illustrations and applications, multi-phase flows and collaborations with industry. The idea is also to bring together developers and users of different numerical approaches and codes to share their experience in the development and validation of the algorithms and discuss the difficulties and limitations of the different methods and their pros and cons. The focus will be mainly on fixed-grid methods, however adaptive grids will be also partly broached, with the aim to compare and validate the different approaches and models.
Author: Nasser Ashgriz
Publisher: Springer Science & Business Media
ISBN: 1441972641
Category : Technology & Engineering
Languages : en
Pages : 922
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Book Description
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.
Author: Daniel Livescu
Publisher: Springer Nature
ISBN: 9811526435
Category : Technology & Engineering
Languages : en
Pages : 273
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Book Description
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.
Author: Vincent Henri Marie Le Chenadec
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
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.
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.
