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Author: Harsh Purwar Publisher: ISBN: Category : Languages : en Pages : 129
Book Description
Fuel atomization plays a very crucial role in determining the overall efficiency of diesel internal combustion engines. This work focuses on developing fast optical diagnostic tools for the study of the liquid fuel atomization with an aim to characterize the fuel sprays in the near-field of the injector nozzle. At first, classical imaging techniques using continuous illumination with a high-speed camera and an ultra-short pulsed illumination with a high-resolution CCD camera are reviewed. Next, the possibility of supercontinuum (SC) derived illumination is investigated. It was observed that the spray images obtained with such an illumination were almost free from laser speckle, which tremendously improved the clarity of these images. An application of the classical imaging technique to a preliminary study of cavitation inside a transparent injector is presented. In the next part of the thesis optical techniques to reduce the noise originating due to the multiple scattering of light from its interaction with the fuel spray are studied. Optical Kerr effect based time-gate in its primitive crossed-beam configuration is reviewed and a novel approach with collinear overlap of the pump and probe beams for time-resolved imaging of fuel spray with time resolution 1 ps is proposed. Ballistic images of fuel spray in the near-nozzle region with high spatial resolution are obtained. The possibility of using SCderived illumination with the optical time-gate configuration is also discussed. Preliminary time-gated spray images obtained by using SC-derived probe beam for spray illumination in the optical-gate setup shows that laser speckle is substantially reduced maintaining a similar time resolution. The change in the optical polarization properties of the Kerr medium on introduction of the pump pulse are completely characterized by measuring its Mueller matrix (MM). The polarization parameters - depolarization, diattenuation, and retardance are then quantified by decomposing the measured MM using polar decomposition formalism.
Author: Harsh Purwar Publisher: ISBN: Category : Languages : en Pages : 129
Book Description
Fuel atomization plays a very crucial role in determining the overall efficiency of diesel internal combustion engines. This work focuses on developing fast optical diagnostic tools for the study of the liquid fuel atomization with an aim to characterize the fuel sprays in the near-field of the injector nozzle. At first, classical imaging techniques using continuous illumination with a high-speed camera and an ultra-short pulsed illumination with a high-resolution CCD camera are reviewed. Next, the possibility of supercontinuum (SC) derived illumination is investigated. It was observed that the spray images obtained with such an illumination were almost free from laser speckle, which tremendously improved the clarity of these images. An application of the classical imaging technique to a preliminary study of cavitation inside a transparent injector is presented. In the next part of the thesis optical techniques to reduce the noise originating due to the multiple scattering of light from its interaction with the fuel spray are studied. Optical Kerr effect based time-gate in its primitive crossed-beam configuration is reviewed and a novel approach with collinear overlap of the pump and probe beams for time-resolved imaging of fuel spray with time resolution 1 ps is proposed. Ballistic images of fuel spray in the near-nozzle region with high spatial resolution are obtained. The possibility of using SCderived illumination with the optical time-gate configuration is also discussed. Preliminary time-gated spray images obtained by using SC-derived probe beam for spray illumination in the optical-gate setup shows that laser speckle is substantially reduced maintaining a similar time resolution. The change in the optical polarization properties of the Kerr medium on introduction of the pump pulse are completely characterized by measuring its Mueller matrix (MM). The polarization parameters - depolarization, diattenuation, and retardance are then quantified by decomposing the measured MM using polar decomposition formalism.
Author: Rami Zakaria Publisher: ISBN: Category : Languages : en Pages :
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: National Research Council Publisher: National Academies Press ISBN: 030916463X Category : Science Languages : en Pages : 222
Book Description
Scientists and engineers have long relied on the power of imaging techniques to help see objects invisible to the naked eye, and thus, to advance scientific knowledge. These experts are constantly pushing the limits of technology in pursuit of chemical imagingâ€"the ability to visualize molecular structures and chemical composition in time and space as actual events unfoldâ€"from the smallest dimension of a biological system to the widest expanse of a distant galaxy. Chemical imaging has a variety of applications for almost every facet of our daily lives, ranging from medical diagnosis and treatment to the study and design of material properties in new products. In addition to highlighting advances in chemical imaging that could have the greatest impact on critical problems in science and technology, Visualizing Chemistry reviews the current state of chemical imaging technology, identifies promising future developments and their applications, and suggests a research and educational agenda to enable breakthrough improvements.
Author: Akhilendra Pratap Singh Publisher: Springer Nature ISBN: 9811615829 Category : Technology & Engineering Languages : en Pages : 269
Book Description
This monograph covers different aspects of internal combustion engines including engine performance and emissions and presents various solutions to resolve these issues. The contents provide examples of utilization of methanol as a fuel for CI engines in different modes of transportation, such as railroad, personal vehicles or heavy duty road transportation. The volume provides information about the current methanol utilization and its potential, its effect on the engine in terms of efficiency, combustion, performance, pollutants formation and prediction. The contents are also based on review of technologies present, the status of different combustion and emission control technologies and their suitability for different types of IC engines. Few novel technologies for spark ignition (SI) engines have been also included in this book, which makes this book a complete solution for both kind of engines. This book will be useful for engine researchers, energy experts and students involved in fuels, IC engines, engine instrumentation and environmental research.
Author: Harsh Purwar
Author: Harsh Purwar
Author: Jaclyn E. Nesbitt
Author: Pan Xiao
Author: Rami Zakaria
Author: 
Author: National Research Council
Author: 
Author: Akhilendra Pratap Singh
Author: 
Author: Arthur McClelland