Optical Investigations of the Sprays Generated by Gasoline Multi-hole Injectors Under Novel Operating Conditions PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Optical Investigations of the Sprays Generated by Gasoline Multi-hole Injectors Under Novel Operating Conditions PDF full book. Access full book title Optical Investigations of the Sprays Generated by Gasoline Multi-hole Injectors Under Novel Operating Conditions by Andrew Wood. Download full books in PDF and EPUB format.
Author: Andrew Wood
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Author: Andrew Wood
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Author: R. Z. Van Romunde
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
The spray form development from a state of the art multi-hole injector for gasoline direct injection internal combustion engines is examined to attempt to determine the thermo-fluid dynamics affecting the spray development. The current state of knowledge regarding spray break-up and the interactivity of the factors on spray form are detailed. The spray under investigation was injected into purposely designed quiescent chambers to decouple the effects of the fluid mechanics on spray development from any in-engine effects. The pressure chambers, experimental apparatus and techniques used to characterise and measure the spray properties are described along with an assessment of any sources of variability in the measurement and analysis methodologies and hardware. Initial spray images of the spray produced by a range of multi-component "retail" fuels as well as single component non-oxygenated and oxygenated hydrocarbons with a range of boiling ranges and points for different injector body (and hence assumed fuel) temperatures and chamber gas pressures are presented. The experimental measurements show the strong interaction between the operational conditions in relation to the fuel properties and the physical spray form. A large amount of deviation from the nominal "ambient" spray form is observed for conditions where the fuel's bubble point (boiling temperature at given gas pressure) is exceeded by a multiple of 10, termed spray collapse. The dependence of a multi-component fuel on the boiling characteristics of its highest volatility components suggest that it is these components which drive the fuel spray development formation, which is further illustrated by comparing different single component fluids. This suggests that higher volatility fluids are better representatives of full range, multi-component fuels for modelling or other investigative work when a single component fuel is required to be used. The onset of spray collapse was found to be gradual with no sudden "threshold" condition at which collapse occurred, also illustrated by a gradual reduction in measured spray droplet size with increasing injector body temperature and/or reducing gas pressure. The physical factors affecting spray development and break-up, and their effects are examined including the fluid flow inside a real size transparent, optically accessed nozzle, illustrating the effect of cavitation supplying nucleation sites for the subsequent vaporisation of the fuel. The scales of local air turbulence are found to affect the local vapour concentration, and hence vaporisation rate, and hence the interaction of these factors is shown to determine the spray formation.
Author: Meghnaa Paresh Dhanji
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Author: Sampath K. Rachakonda
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Gasoline engines operating under the principle of direct injection are susceptible to flash-boiling due to superheated nature of the fuel and the sub-atmospheric in-cylinder pressures during injection. A review of the literature on flash-boiling sprays shows that a majority of the studies have focused on the far-field regions of the spray, with limited attention given to understanding the influences of the injector geometry and the near-nozzle regions of the spray. Modeling the internal nozzle flow and the primary atomization, on which the far-field spray depends, is a challenge. This thesis, therefore, is aimed at understanding the complex flow through a fuel injector nozzle and the nature of the spray in the near-nozzle region, with the help of computer simulations under flash-boiling and non-flash-boiling conditions. In the current study, the simulations were performed using an in-house Eulerian CFD solver called HRMFoam. Improvements to the solver's near-nozzle spray modeling capability are discussed. These improvements include the implementation of a liquid-gas interface-area-density transport equation to model the primary atomization process. The simulations of direct injection of gasoline and gasoline-like sprays were performed on single-hole and multi-hole injectors, for a wide range of operating conditions. Spray characteristics such as the nozzle's coefficient of discharge and the mean droplet diameter in the dense region of the spray were seen to be captured adequately well with the help of a 2D axi-symmetry assumption in the case of single-hole injectors. A novel approach to identify the near-nozzle spray plume boundary in CFD simulations is presented and validated against experimental measurements for a single-hole asymmetric injector. Case studies on single-hole asymmetric injectors revealed a direct correlation between the drill angle of the nozzle and near-nozzle spray plume angle. A hypothesis of the similarity between a stepped-hole two-phase nozzle and a conventional single-phase converging-diverging nozzle is presented. Furthermore, it was observed that flash-boiling jets behave as underexpanded jets, and therefore, are wider. Whereas, non-flash-boiling behave as overexpanded jets, and thus are narrower. Through the case studies on multi-hole injectors, the collapse of the spray or lack thereof was qualitatively and quantitatively characterized. In this process, a resemblance between the experimentally and computationally identified spray collapse mechanism was established. The application of LES modeling to internal and near-nozzle GDI sprays was explored in a pilot study, and the results were qualitatively validated against the experimentally available near-nozzle X-ray radiography measurements. Finally, in another pilot study, an attempt to model the interphase slip velocity is discussed.
Author: Rami Zakaria
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
This thesis was initiated by the need to develop a stable low vibration engine with a high power to weight ratio. A new rotary (Wankel) engine was chosen to meet these requirements. A further operating criterion was that the engine was required to use JP8 (aviation fuel). The difficulty created by the use of JP8 is that its combustion temperature is higher than other conventional fuels, and preheating is necessary, especially in the case of cold start. Thus, the question posed was, could a more appropriate and efficient method of fuel delivery be devised? This thesis presents the design and construction of a fluid spray visualisation system for investigating the macroscopic and microscopic characteristics of fuel sprays using low injection pressure up to 10 bar (1 MPa). Laser imaging techniques have been used for data acquisition. The thesis has been divided into several aspects. Firstly, a background study of fluid sprays and fuel injection strategies was carried out. This has centred on the relationship between droplet size and the combustion process. It further investigated what differentiated the fuel delivery approach to Wankle from that to other engines. Secondly, two families of fuel injector were tested and evaluated within the optical engineering laboratory using deionised water (DI) water for safety reasons. The first family involved conventional gasoline injectors with several nozzle arrangements. The second family involved medical nebulisers with several nozzle diameters. The evaluation of the fuel injectors required developing a fluid delivery circuit, and a specific ECU (Electronic Control Unit) for controlling pulse delivery and imaging instrument. The company associated with the project then set up a test cell for performing experiments on JP8 fuel. The initial global visualisation of the jet spray was made using a conventional digital camera. This gave a measurement of the spray angle and penetration length. However, as the study moved to the more precise determination of the fuel spray particulate size, a specialised Nd:YAG laser based diagnostic was created combined with a long range diffraction limited microscope. Microscopic characterisation of the fuel sprays was carried out using a backlight shadowgraph method. The microscopic shadowgraphy method was applied successfully to resolve droplets larger than 4 microns in diameter. The spray development process during an individual fuel injection cycle was investigated, presenting the frequency response effect of electronic fuel injectors (EFI) on the spray characteristics when operating at high injection frequencies (0.25 -- 3.3 kHz). The velocity distribution during the different stages of an injection cycle was investigated using PIV. The influence of the injection pressure on the spray pattern and droplet size was also presented. Novel fluid atomisation systems were investigated for the capability of generating an optimum particulate distribution under low pressure. Finally, it was found that a new electronic medical nebuliser (micro--dispenser) could be used to deliver the fuel supply with the relevant particle size distribution at low flow rate and high injection frequency. However, as yet it has not been possible to apply this approach to the engine; it is hoped that it will yield a more efficient method of cold starting the engine. The characteristics of this atomiser can be applied to provide a controllable fuel supply approach for all rotary engines to improve their fuel efficiency. The second part of this research discusses the droplets--light interaction using Mie scattering for fluid droplets smaller than the microscope visualisation limit (4 microns). Mie scattering theory was implemented into Three--Components Particle Image Velocimetry (3C-- PIV) tests to address a number of problems associated with flow seeding using oil smoke. Mie curves were used to generate the scattering profile of the oil sub--micron droplets, and therefore the scattering efficiency can be calculated at different angles of observation. The results were used in jet flow PIV system for the determination of the optimum position of the two cameras to generate balanced brightness between the images pairs. The brightness balance between images is important for improving the correlation quality in the PIV calculations. The scattering efficiency and the correlation quality were investigated for different seeding materials and using different interrogation window sizes.
Author: Institution of Mechanical Engineers
Publisher: Elsevier
ISBN: 0857096044
Category : Technology & Engineering
Languages : en
Pages : 348
Get Book Here
Book Description
This book presents the papers from the latest conference in this successful series on fuel injection systems for internal combustion engines. It is vital for the automotive industry to continue to meet the demands of the modern environmental agenda. In order to excel, manufacturers must research and develop fuel systems that guarantee the best engine performance, ensuring minimal emissions and maximum profit. The papers from this unique conference focus on the latest technology for state-of-the-art system design, characterisation, measurement, and modelling, addressing all technological aspects of diesel and gasoline fuel injection systems. Topics range from fundamental fuel spray theory, component design, to effects on engine performance, fuel economy and emissions. - Presents the papers from the IMechE conference on fuel injection systems for internal combustion engines - Papers focus on the latest technology for state-of-the-art system design, characterisation, measurement and modelling; addressing all technological aspects of diesel and gasoline fuel injection systems - Topics range from fundamental fuel spray theory and component design to effects on engine performance, fuel economy and emissions
Author: W. Hentschel
Publisher:
ISBN:
Category :
Languages : en
Pages : 12
Get Book Here
Book Description
Author: PengBo Dong
Publisher:
ISBN:
Category : Electronic books
Languages : en
Pages : 0
Get Book Here
Book Description
Faced with dual challenges of ,Äúcarbon neutral,Äù and emission control, fossil fuel-based internal combustion engines need to explore new ways and technical paths to reduce harmful emissions and Carbon dioxide emissions simultaneously. Fuel injection process is playing a significant role not only in traditional engines but also in new low/zero carbon engines. Multi-hole nozzles have a wide range of applications in the fuel supply system. While the accepted spray study work and jet break-up models are usually developed under the quasi-steady-state of fuel injection by a single-hole nozzle. There are rare models that can describe the whole break-up processes of multi-hole nozzle spray, including complex internal flow factors, plume interaction, and the effect of start/end of injection. In this chapter, characteristics of spray morphology, evolution processes, and evaporation characteristics, emerging from the practical diesel multi-hole nozzles, were discussed and analyzed during the transient injection processes in detail. Moreover, the relationship between multi-hole nozzle internal flow properties and the corresponding spray behaviors was investigated by numerical simulation method systematically. Therefore, multi-hole spray modeling processes under engine operating conditions and the optimized design of diesel multi-hole nozzles are expected to get some benefits and clues from the current results.
Author: Milad Mirshahi
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Author: T. Behrendt
Publisher:
ISBN:
Category :
Languages : de
Pages :
Get Book Here
Book Description
