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Book A Comparison Study of Liquid and Vapor Phase Development at Spray Boundary of Diesel Spray BDF and SVO Spray

Download or read book A Comparison Study of Liquid and Vapor Phase Development at Spray Boundary of Diesel Spray BDF and SVO Spray written by Adam Mohd Izhan Noor Azam and published by . This book was released on 2012 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of biodiesel as an alternative diesel engine fuel is preferred for fossil fuel substitution. However, due to technical deficiencies, they are rarely used purely or with high percentages in unmodified diesel engines. Therefore, this project is to study spray simulation of diesel, biodiesel fuel (BDF) and straight vegetable oil (SVO) in the diesel chamber. Two main components are focused on this paper. First, the relations between the viscosities of different fuels and the spray characteristics in achieving stoichiometric air-fuel mixture are investigated. Lastly the spray liquid-vapor phase in chamber is investigated. Good spray characteristics lead to the good drivability, high combustion efficiency and stoichiometric air-fuel mixture. Therefore, Computational Fluid Dynamics (CFD) method using ANSYS Fluent simulation software is used for this purpose. The simulation of injection spray in chamber is conducted by using three type of fuel that is diesel, biodiesel and palm oil with the one 0.2mm valve covered orifice (VCO) nozzle, injection pressure at 700 MPA, ambient pressure at 10 MPA, ambient temperature at 300 K and same iteration time. The results are shown by changing the type of fuel. The simulation results showed that the spray characteristics are better for diesel at the same time iteration compared to BDF and SVO by the penetration length, cone angle and liquid-vapor phase data.

Book An Integrated Approach to Spray Combustion Model Development

Download or read book An Integrated Approach to Spray Combustion Model Development written by W. A. Sirignano and published by . This book was released on 1986 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Large eddy Simulation Modeling of Diesel Sprays

Download or read book Large eddy Simulation Modeling of Diesel Sprays written by Chi-Wei Tsang and published by . This book was released on 2017 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this study is to develop/improve physical models for large-eddy simulations of Diesel sprays. The stochastic Kelvin-Helmholtz/Rayleigh-Taylor (KH-RT) atomization and breakup model, the synthetic eddy injection model, the droplet rotation model, and the sub-grid scale (SGS) dispersion model were developed and tested. Using the classical KH-RT model, it was found that simulation results are sensitive to several model parameters such as length and time scales of instability waves. The idea of the stochastic KH-RT model is to determine these parameters stochastically and dynamically. This is an attempt to reduce the sensitivity of the model parameters partly resulting from the incapability of predicting breakup mechanisms other than wave instabilities in the classical KH-RT model. The synthetic eddy injection model predicts fluctuations of the Lagrangian parcel initial velocity. The model attempts to simulate turbulence at the nozzle exit without the need of internal nozzle flow simulations, by superimposing a number of virtual coherent structures. The performance of these two newly developed models was compared to the original ones, namely the classical KH-RT and the cone angle injection models. Two experimental databases, the Engine Combustion Network (ECN) constant-volume sprays and the Engine Research Center optical engine sprays were used to validate the models. A number of simulated quantities such as liquid projected mass density, liquid and vapor penetrations, fuel vapor profiles, ignition delays, and lift-off lengths, were compared against the data. The stochastic KH-RT model improved the prediction of the projected mass density downstream and liquid penetrations in a range of operating conditions (errors within 5 %) without tuning the model constants case by case. The synthetic eddy injection model improved the prediction of vapor penetrations at early stage of injection since the development of instability modes and turbulent transport in the near-nozzle region were better resolved. The model also shows less grid sensitivity. Overall, using these two new models overcomes some limitations in the original models and makes LES as a more predictive tool for Diesel sprays. The droplet rotation model considers droplet force and torque due to relative rotational motions between droplets and gas. Simulation results of the ECN non-vaporizing and vaporizing sprays with and without using the rotation model were compared. It was found that the droplet rotation has negligible effect. This is because the droplet response time scale to the rotational motion is much smaller than that to the translational motion. That is, slip angular velocity approaches to zero much faster, resulting in much smaller rotational force than the drag force. The SGS dispersion model considers the effect of sub-grid motions on Diesel spray dispersion. The model assumes that the SGS dispersion velocity is decomposed into the deterministic and the stochastic parts. The deterministic part is modeled by the approximate deconvolution method and the stochastic part is assumed to be isotropic and Gaussian distributed. It was found that the two model parameters, variance of the Gaussian distribution and turbulence correlation time, have a critical effect on the spatial distribution of droplets with small inertia downstream of the spray. Larger variance or longer turbulence correlation time predicts wider liquid spray angle. However, they have small effect on predicting resolved gas-phase statistics. The primary reason for this is that the motion of high-momentum liquid blobs in the near-nozzle region leading to air entrainment and subsequent gas jet development is little influenced by the SGS dispersion. Moving further downstream a quasi-equilibrium is established between the two phases, resulting in relatively small slip velocities. Therefore, it was found that the spray momentum source term in the gas momentum equation is much smaller than the other terms in the downstream region.

Book Quantitative Vapor Phase Imaging of In cylinder Diesel Fuel Sprays

Download or read book Quantitative Vapor Phase Imaging of In cylinder Diesel Fuel Sprays written by Mark Sean Beckman and published by Ann Arbor, Mich. : University Microfilms International. This book was released on 2004 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Quantitative 2 D Fuel Vapor Concentration Measurements in an Evaporating Diesel Spray Using the Exciplex Fluorescence Method

Download or read book Quantitative 2 D Fuel Vapor Concentration Measurements in an Evaporating Diesel Spray Using the Exciplex Fluorescence Method written by Tongwoo Kim and published by . This book was released on 2001 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book A Comparison of Vaporization Models in Spray Calculations

Download or read book A Comparison of Vaporization Models in Spray Calculations written by S. K. Aggarwal and published by . This book was released on 1984 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of different gas- and liquid-phase models on the vaporization behavior of a single-component isolated droplet are studied for both stagnant and convection situations in a high-temperature gas environment. In conjunction with four different liquid-phase models, namely, d2 law, infinite conductivity, diffusion limit, and internal vortex circulation, the different gas-phase models include a spherically symmetric model in the stagnant case and Ranz-Marshall correlation plus two other axisymmetric models in the convective case. A critical comparison of all these models is made. The use of these models in a spray situation is examined. A transient one-dimensional flow of an air-fuel droplet mixture is considered. It is shown that the fuel vapor mass fraction can be very sensitive to the particular liquid- and gas-phase models. The spherically symmetric conduction or diffusion limit model is recommended when the droplet Reynolds number is negligible compared to unity, while the simplified vortex model accounting for internal circulation is suggested when the droplet Reynolds number is large compared to unity. Keywords include: Spray; Droplet; Evaporation; Combustion; Modeling.

Book A Study of the Breakup and Atomization of a Combusting Diesel Fuel Spray by Phase Doppler Anemometry

Download or read book A Study of the Breakup and Atomization of a Combusting Diesel Fuel Spray by Phase Doppler Anemometry written by G. Pitcher and published by . This book was released on 1992 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fuel droplet velocity and size measurements have been obtained in a combusting Diesel spray inside a single-cylinder direct injection Diesel engine. The measurements were made in the near nozzle region by phase Doppler anemometry with high spatial and temporal resolution. An analysis of the data describes the fuel spray breakup and atomization based on a liquid jet and model and identifies three distinct zones in the developing spray. (Author).

Book Experimental Study of Diesel Spray Characteristics and Atomization

Download or read book Experimental Study of Diesel Spray Characteristics and Atomization written by Chan-Teng Chang and published by . This book was released on 1997 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Quantification of Spray Characteristics Associated with Unique Diesel Injector Nozzles

Download or read book Quantification of Spray Characteristics Associated with Unique Diesel Injector Nozzles written by Erica Lynn Blobaum and published by . This book was released on 2001 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Liquid Sprays and Flow Studies in the Direct Injection Diesel Engine Under Motored Conditions

Download or read book Liquid Sprays and Flow Studies in the Direct Injection Diesel Engine Under Motored Conditions written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-11-10 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: A two dimensional, implicit finite difference method of the control volume variety, a two equation model of turbulence, and a discrete droplet model were used to study the flow field, turbulence levels, fuel penetration, vaporization, and mixing in diesel engine environments. The model was also used to study the effects of engine speed, injection angle, spray cone angle, droplet distribution, and intake swirl angle on the flow field, spray penetration and vaporization, and turbulence in motored two-stroke diesel engines. It is shown that there are optimum conditions for injection, which depend on droplet distribution, swirl, spray cone angle, and injection angle. The optimum conditions result in good spray penetration and vaporization and in good fuel mixing. The calculation presented clearly indicates that internal combustion engine models can be used to assess, at least qualitatively, the effects of injection characteristics and engine operating conditions on the flow field and on the spray penetration and vaporization in diesel engines. Nguyen, Hung Lee and Carpenter, Mark H. and Ramos, Juan I. and Schock, Harold J. and Stegeman, James D. Glenn Research Center; Langley Research Center...

Book Investigation of Impinged Diesel Spray Hydrodynamics and Heat Transfer

Download or read book Investigation of Impinged Diesel Spray Hydrodynamics and Heat Transfer written by Richard A. Booth and published by . This book was released on 1994 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: