Download or read book Modeling Superheated Fuel Sprays and Vaporization for GDI Engines Using Single and Multi component Fuel Models written by André Marques Gomes and published by . This book was released on 2001 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cfd Modeling of Superheated Fuel Sprays written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2019-01-13 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: An understanding of fuel atomization and vaporization behavior at superheat conditions is identified to be a topic of importance in the design of modern supersonic engines. As a part of the NASA aeronautics initiative, we have undertaken an assessment study to establish baseline accuracy of existing CFD models used in the evaluation of a ashing jet. In a first attempt towards attaining this goal, we have incorporated an existing superheat vaporization model into our spray solution procedure but made some improvements to combine the existing models valid at superheated conditions with the models valid at stable (non-superheat) evaporating conditions. Also, the paper reports some validation results based on the experimental data obtained from the literature for a superheated spray generated by the sudden release of pressurized R134A from a cylindrical nozzle. The predicted profiles for both gas and droplet velocities show a reasonable agreement with the measured data and exhibit a self-similar pattern similar to the correlation reported in the literature. Because of the uncertainty involved in the specification of the initial conditions, we have investigated the effect of initial droplet size distribution on the validation results. The predicted results were found to be sensitive to the initial conditions used for the droplet size specification. However, it was shown that decent droplet size comparisons could be achieved with properly selected initial conditions, For the case considered, it is reasonable to assume that the present vaporization models are capable of providing a reasonable qualitative description for the two-phase jet characteristics generated by a ashing jet. However, there remains some uncertainty with regard to the specification of certain initial spray conditions and there is a need for experimental data on separate gas and liquid temperatures in order to validate the vaporization models based on the Adachi correlation for a liquid involving R134A.
Download or read book Modeling Multicomponent Fuel Sprays in Engines with Application to Diesel Cold starting written by Nabil S. Ayoub and published by . This book was released on 1995 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling Multi component Fuel Evaporation Flame Propagation and Chemical Kinetics Processes for GDI Engines written by Shiyou Yang and published by . This book was released on 2010 with total page 237 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling of Flash Boiling Flows in Injectors with Gasoline ethanol Fuel Blends written by Kshitij Neroorkar and published by . This book was released on 2011 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flash boiling may be defined as the finite-rate mechanism that governs phase change in a high temperature liquid that is depressurized below its vapor pressure. This is a transient and complicated phenomenon which has applications in many industries. The main focus of the current work is on modeling flash boiling in injectors used in engines operating on the principle of gasoline direct injection (GDI). These engines are prone to flash boiling due to the transfer of thermal energy to the fuel, combined with the sub-atmospheric pressures present in the cylinder during injection. Unlike cavitation, there is little tendency for the fuel vapor to condense as it moves downstream because the fuel vapor pressure exceeds the downstream cylinder pressure, especially in the homogeneous charge mode. In the current work, a pseudo-fluid approach is employed to model the flow, and the non-equilibrium nature of flash boiling is captured through the use of an empirical time scale. This time scale represents the deviation from thermal equilibrium conditions. The fuel composition plays an important role in flash boiling and hence, any modeling of this phenomenon must account for the type of fuel being used. In the current work, standard, NIST codes are used to model single component fluids like n-octane, n-hexane, and water, and a multi-component surrogate for JP8. Additionally, gasoline-ethanol blends are also considered. These mixtures are azeotropic in nature, generating vapor pressures that are higher than those of either pure component. To obtain the properties of these fuels, two mixing models are proposed that capture this non-ideal behavior. Flash boiling simulations in a number of two and three dimensional nozzles are presented, and the flow behavior and phase change inside the nozzles is analyzed in detail. Comparison with experimental data is performed in cases where data are available. The results of these studies indicate that flash boiling significantly affects the characteristics of the nozzle spray, like the spray cone angle and liquid penetration into the cylinder. A parametric study is also presented that can help understand how the two different time scales, namely the residence time in the nozzle and the vaporization time scale, interact and affect the phenomenon of flash boiling.
Download or read book AN EXPERIMENTAL AND COMPUTATIONAL STUDY OF FUEL SPRAY INTERACTION written by and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : An efficient spray injection results in better vaporization and air-fuel mixing, leading to combustion stability and reduction of emissions in the internal combustion (IC) engines. The impingement of liquid fuels on chamber wall or piston surface in IC engines is a common phenomenon and fuel film formed in the spray-piston or cylinder wall impingement plays a critical role in engine performance and emissions. Therefore, the study of the spray impingement on the chamber wall or position surface is necessary. To understand the spray-wall interaction, a single droplet impingement on a solid surface with different conditions was first examined. The droplet-wall interaction outcomes, in particular focusing on the splashing criteria, were inspected and post-impingement characterizations including spreading factor, height ratio, contact line velocity, and dynamic contact angle was further analyzed based on the experimental data. The non-evaporation volume of fluid (VOF) model based on Eulerian approach was used to characterize single droplet impinging on the wall and provide a better understanding of the dynamic impact process. In addition, the study of droplet-to-droplet collision and multi-droplet impingement on a solid surface are performed, which is essential to aid in the spray-wall impingement investigation. As well, due to the evaporation drawing more attention during the engine combustion process, an evaporation VOF sub-model was developed and applied to multi-droplet impingement on a hot surface to qualitatively and quantitatively analyze the vaporizing process as droplets impacting onto the hot surface. After that, the non-vaporizing and vaporizing spray characteristics of spray-wall impingement at various operating conditions relevant to diesel engines were undertaken, with spray characterized using schlieren and Mie scattering diagnostics, as well as Refractive Index Matching (RIM) technique. Free and impinged spray structures and deposited wall-film formation and evaporation were qualitatively analyzed, spray properties and wall-film properties were quantified, and surface temperature and heat flux were measured. An Eulerian-Lagrangian modeling approach was employed to characterize the spray-wall interactions by means of a Reynolds-Averaged Navier-Stokes (RANS) formulation. The local spray characteristics in the vicinity of the wall and the local spray morphology near the impingement location were studied. Furthermore, multiple spray-to-spray collision derived from droplet-to-droplet collision, considering as one of the advanced injection strategies to enhance the engine performance, was studied at various gasoline engine conditions to explore the effect of colliding spray on spray related phenomena like atomization, vaporization, and mixing. Spray characteristics were obtained by the schlieren diagnostics and the experimental validated Computational Fluid Dynamic (CFD) simulations were based on Eulerian-Lagrangian approach to understand the mechanism behind the collisions of sprays and characterize the different types of multiple spray-to-spray collision. In summary, on the strength of the study of droplet-wall impingement and droplet-to-droplet collision at non-evaporation and evaporation states, the main objective of this dissertation is to enhance the understanding of spray-wall impingement and multiple spray-to-spray collision under diesel or gasoline engine conditions from both experiments and CFD simulations, therefore providing feedbacks to the ultimate task in future development and application of a more reliable and effective fuel injection system.
Download or read book An Experimental Investigation of a Homogeneous Charge Compression Ingnition Engine Using Low Pressure Injection and Diesel Fuel written by Eric John Hruby and published by . This book was released on 2003 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling of Multi component Fuel Vaporization for Spray Simulations Using Continuous Thermodynamics written by Dongyao Wang and published by . This book was released on 2004 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling the Influence of Molecular Interactions on the Vaporization of Multi component Fuel Sprays written by Qi Jiao and published by . This book was released on 2010 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Droplets and Sprays written by Saptarshi Basu and published by Springer. This book was released on 2017-12-11 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on droplets and sprays relevant to combustion and propulsion applications. The book includes fundamental studies on the heating, evaporation and combustion of individual droplets and basic mechanisms of spray formation. The contents also extend to the latest analytical, numerical and experimental techniques for investigating the behavior of sprays in devices like combustion engines and gas turbines. In addition, the book explores several emerging areas like interactions between sprays and flames and the dynamic characteristics of spray combustion systems on the fundamental side, as well as the development of novel fuel injectors for specific devices on the application side. Given its breadth of coverage, the book will benefit researchers and professionals alike.
Download or read book Modeling of Multicomponent Fuel Vaporization in Internal Combustion Engines written by Yangbing Zeng and published by . This book was released on 2000 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Investigation Of Spray Characterization Of Heater GDI System written by and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Gasoline engines require fuel enrichment at low temperature cranking (cold start) conditions for efficient engine operation. Since the amount of fuel injected is high at cold start to compensate low fuel evaporation, fuel sprays tend to impinge on the cold surfaces of the piston and cylinder walls leading to the formation of excessive unburned hydrocarbons. One of the ways to ensure reliable cold start performance and to reduce UHC emissions is to have the fuel subjected to preheating. The objective of this study is to investigate the effects of fuel preheating on Gasoline Direct Injection sprays to improve the mixture preparation during the cold start conditions. Injection of fuel sprays of neat gasoline and gasoline-ethanol blends (E10 and E85) from the heater-injector into a constant volume combustion chamber was studied. Computational Fluid Dynamics (CFD) simulations of the fuel flow through the injector were performed to understand the impact of the heater in improving the mixture preparation quality. The gasoline was modelled with 14 component surrogate fuel model to capture its physical properties and distillation characteristics. Fuel spray processes in the Constant Volume Combustion Chamber (CVCC) were simulated using an in-house CFD code, MTU-KIVA. Parametric simulations were performed at different injection pressures and at a wide range of fuel temperature ranging from -6°C to 250°C. The simulation of injector internal flow could improve the spray simulations in the CVCC by providing accurate velocity and temperature distributions of fuel sprays at the exit of individual nozzles. The results show that the injector with the preheating system performs reliably at cold start conditions to increase the fuel temperature from -6°C to 75°C in less than a second. The spray were in good agreement between the measurements and predictions. For the given operating range, the spray changes from normal evaporation to flash boiling regime. The model captures the spray collapsing behaviour for the flash boiling conditions. However, the model tends to over-predict the spray penetration for fuel temperatures in the higher range of boiling/flash boiling, regardless of the injection pressure variation.
Download or read book Modeling Engine Spray and Combustion Processes written by Gunnar Stiesch and published by Springer. This book was released on 2014-03-12 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: The utilization of mathematical models to numerically describe the performance of internal combustion engines is of great significance in the development of new and improved engines. Today, such simulation models can already be viewed as standard tools, and their importance is likely to increase further as available com puter power is expected to increase and the predictive quality of the models is constantly enhanced. This book describes and discusses the most widely used mathematical models for in-cylinder spray and combustion processes, which are the most important subprocesses affecting engine fuel consumption and pollutant emissions. The relevant thermodynamic, fluid dynamic and chemical principles are summarized, and then the application of these principles to the in-cylinder processes is ex plained. Different modeling approaches for the each subprocesses are compared and discussed with respect to the governing model assumptions and simplifica tions. Conclusions are drawn as to which model approach is appropriate for a specific type of problem in the development process of an engine. Hence, this book may serve both as a graduate level textbook for combustion engineering stu dents and as a reference for professionals employed in the field of combustion en gine modeling. The research necessary for this book was carried out during my employment as a postdoctoral scientist at the Institute of Technical Combustion (ITV) at the Uni versity of Hannover, Germany and at the Engine Research Center (ERC) at the University of Wisconsin-Madison, USA.
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:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2004 with total page 772 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Modeling of Spray Primary Breakup with Application to Diesel Engines written by Yong Yi and published by . This book was released on 2002 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Unified Fuel Spray Breakup Model for Internal Combustion Engine Applications written by Christos Chryssakis and published by . This book was released on 2005 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:
