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Author: Yong Chuan Khoo Publisher: ISBN: Category : Languages : en Pages :
Book Description
Recent developments in automotive engines have been directed towards the reduction of engine emissions in order to minimise their effect on the environment. A major part of this advancement has been the improvement of new direct injection injectors providing improved atomisation and better control of the fuel delivery into the combustion chamber. To aid the injector design process, it is vital to understand the fundamental fluid dynamic processes controlling atomisation of high-pressure fluids in Direct Injection injectors. The research effort is directed towards the ability to link changes to the internal nozzle geometry and flow field to the external atomisation processes. This thesis presents a detailed laser diagnostic investigation of Diesel and gasoline direct injectors for automotive applications. There is a need to increase our understanding of injector flow processes occurring both internally and externally to a high-pressure fuel atomiser and the physical phenomena in generating atomised fuel in the combustion chamber. The characterisation of Diesel injector flow was achieved by the use of series of real-sized, optically accessible sapphire Diesel injectors, capable of operating at realistic driving pressures through orifice nozzles of 0.15 mm and 0.3 mm diameter. High-speed, laser-illuminated flow visualisation was used to study the effect of injector geometry on the internal flow field and the nearfield external spray structure. Data in this thesis shows that operating an injector with a counterbore provides a methodology for controlling spray angle. The study of gasoline injectors was to develop and apply innovative measurement techniques, using a series of real-sized (1 mm diameter) optical nozzles, to provide data to link the internal flow structure to the external spray development. The investigation of non-swirl flow with sharp-edged inlets nozzle showed that cavitation completely controls the flow development. Fluorescent Particle Image Velocimetry (FPIV) experiments on all chamfered inlet nozzles (30°, 45° and 60°) showed that the total velocity increased linearly with driving pressure. High-speed flow visualisation study showed that high-pressure swirl injectors generate tapered aircore in the 30° and 45° chamfered inlet orifice and parallel aircores for 60° chamfered inlet orifices. The results also showed that the film thickness was dependent of driving pressure and nozzle geometry. Application of fluorescent particle image velocimetry (FPIV) was used to provide results for internal flow velocity field for the full range of injector geometries studied. A semi-empirical relationship was used and the empirical constants was modified to fit the current experimental results. For the final optical diagnostic tool, phase Doppler anemometry (PDA) was used to provide profiles of particle size in the external spray. Examples of particle size results were shown that matched findings presented in the literature.
Author: Yong Chuan Khoo Publisher: ISBN: Category : Languages : en Pages :
Book Description
Recent developments in automotive engines have been directed towards the reduction of engine emissions in order to minimise their effect on the environment. A major part of this advancement has been the improvement of new direct injection injectors providing improved atomisation and better control of the fuel delivery into the combustion chamber. To aid the injector design process, it is vital to understand the fundamental fluid dynamic processes controlling atomisation of high-pressure fluids in Direct Injection injectors. The research effort is directed towards the ability to link changes to the internal nozzle geometry and flow field to the external atomisation processes. This thesis presents a detailed laser diagnostic investigation of Diesel and gasoline direct injectors for automotive applications. There is a need to increase our understanding of injector flow processes occurring both internally and externally to a high-pressure fuel atomiser and the physical phenomena in generating atomised fuel in the combustion chamber. The characterisation of Diesel injector flow was achieved by the use of series of real-sized, optically accessible sapphire Diesel injectors, capable of operating at realistic driving pressures through orifice nozzles of 0.15 mm and 0.3 mm diameter. High-speed, laser-illuminated flow visualisation was used to study the effect of injector geometry on the internal flow field and the nearfield external spray structure. Data in this thesis shows that operating an injector with a counterbore provides a methodology for controlling spray angle. The study of gasoline injectors was to develop and apply innovative measurement techniques, using a series of real-sized (1 mm diameter) optical nozzles, to provide data to link the internal flow structure to the external spray development. The investigation of non-swirl flow with sharp-edged inlets nozzle showed that cavitation completely controls the flow development. Fluorescent Particle Image Velocimetry (FPIV) experiments on all chamfered inlet nozzles (30°, 45° and 60°) showed that the total velocity increased linearly with driving pressure. High-speed flow visualisation study showed that high-pressure swirl injectors generate tapered aircore in the 30° and 45° chamfered inlet orifice and parallel aircores for 60° chamfered inlet orifices. The results also showed that the film thickness was dependent of driving pressure and nozzle geometry. Application of fluorescent particle image velocimetry (FPIV) was used to provide results for internal flow velocity field for the full range of injector geometries studied. A semi-empirical relationship was used and the empirical constants was modified to fit the current experimental results. For the final optical diagnostic tool, phase Doppler anemometry (PDA) was used to provide profiles of particle size in the external spray. Examples of particle size results were shown that matched findings presented in the literature.
Author: Lulin Jiang Publisher: ISBN: Category : Electronic dissertations Languages : en Pages : 207
Book Description
Diminishing fossil fuel resources, ever-increasing energy cost, and the mounting concerns for environmental emissions have precipitated worldwide research on alternative fuels. Biodiesel, a popular renewable energy source, is produced from the transesterification process of source oils such as vegetable oil (VO) requiring processing cost and energy input. However, highly viscous glycerol produced as the waste byproduct also decreases the economically viability of biodiesel. Previous studies show that without fuel preheating or hardware modification, high viscosity fuels such as VO and glycerol cannot be burnt cleanly with the application of the typical air blast (AB) injector due to the high viscosity. However, extremely low emissions of diesel, kerosene, biodiesel, straight VO and glycerol flames at the combustor exit are reported using a novel flow blurring (FB) injector. The PDPA measurements in the FB sprays at least 1.0 cm downstream of the injector exit quantitatively show the superior fuel-flexibility and atomization capability of the FB injector as compared to the AB atomizer. This study seeks to gain insight into the detailed flame structure of both conventional and alternative fuels atomized by the FB injector. The atomization mechanism in the FB injector near field is also investigated using a high speed imaging technique and particle image velocimetry (PIV) to explore the FB spray characteristics in the near field of the injector. First, the combustion of diesel, biodiesel and straight vegetable oil (VO) using a Flow Blurring (FB) injector is investigated. Measurements of gas temperature and CO and NOx concentrations at various axial and radial locations of the combustor are acquired using custom-designed thermocouple and gas sampling probes. Heat loss rate through the combustor is estimated from wall temperatures measured by an infra-red camera. A simple droplet model is used to predict fuel vaporization behaviour in the dark-region near the injector exit. Results show that the FB injector produced low-emission clean blue flames indicating mainly premixed combustion for all three fuels. Matching profiles of heat loss rate and product gas temperature show that the combustion efficiency is fuel independent. Next, a fuel-flexible dual-fuel combustor to simultaneously burn methane and/or straight glycerol without preheating either glycerol or air is investigated by utilizing a FB liquid fuel injector. Product gas temperature, NOX and CO emissions at multiple locations inside the combustor are measured to quantitatively assess the flame structure, related to liquid atomization, droplet evaporation, and fuel-air mixing in the near field. The impact of fuel mix and air to liquid mass ratio (ALR) on combustion performance is investigated. Pure glycerol flame is also investigated to demonstrate the fuel flexibility and ease of switching between gas and liquid fuels in the present system. Results show that the methane combustion can assist glycerol vaporization to results in its rapid oxidation. In spite of the differences in the flame structure, profiles of product gas temperature and emissions at the combustor exit reveal that complete and mainly lean premixed combustion with low emissions is achieved for all of the test cases indicating excellent fuel flexibility of the present combustor using the FB injector. Next, high-speed visualization and time-resolved Particle Image Velocimetry (PIV) techniques are employed to investigate the FB spray in the near field of the injector to delineate the underlying mechanisms of atomization. Experiments are performed using water as the liquid and air as the atomizing gas. Flow visualization at the injector exit focused on field of view with the dimension of 2.3 mm x 1.4 mm, spatial resolution of 7.16 æm per pixel, exposure time of 1 æs, and image acquisition rate of 100 k frames per second (fps). Image sequence illustrates mostly fine droplets indicating that primary breakup by FB atomization occurs within the injector. Few larger droplets appearing at the injector periphery undergo secondary breakup by Rayleigh-Taylor instabilities. Time-resolved PIV technique is applied to quantify the droplet dynamics in the injector near field. Plots of instantaneous, mean, and root-mean-square droplet velocities are presented to reveal the secondary breakup process. Results show that the secondary atomization process to produce fine and stable spray is complete within a short distance of about 5.0 mm from the injector exit. These superior characteristics of the FB injector are desirable to achieve clean combustion of different fuels in practical systems. The impact of ALR shows that the increase in ALR improves both primary FB atomization and secondary atomization in the near field. Next, glycerol atomization in the near field of the FB injector is investigated in detail. Time-resolved PIV with exposure time of 1 ms and laser pulse rate of 15 kHz is utilized to probe the glycerol spray at spatial resolution of 16.83 æm per pixel. PIV results describe the droplet dynamics in terms of the instantaneous, mean, and root-mean-square (RMS) velocities, and space-time analysis and probability distribution profiles of the axial velocity. In addition, high-speed imaging (75 kHz) coupled with backside lighting is applied to reveal the glycerol breakup process at spatial resolution of 7.16 æm per pixel and exposure time of 1 æs. Results show that the primary breakup by FB atomization or bubble explosion within the injector results in a combination of slow-moving streaks and fast-moving droplets at the injector exit. Then, the secondary breakup by Rayleigh-Taylor instability occurs at farther downstream locations where the high-velocity atomizing air stretches the streaks into thin streaks that disintegrate into smaller streaks, and subsequently, into fine droplets. Thus, within a short distance downstream of the injector exit (
Author: Constantine D. Rakopoulos Publisher: Springer Science & Business Media ISBN: 1848823754 Category : Technology & Engineering Languages : en Pages : 408
Book Description
Traditionally, the study of internal combustion engines operation has focused on the steady-state performance. However, the daily driving schedule of automotive and truck engines is inherently related to unsteady conditions. In fact, only a very small portion of a vehicle’s operating pattern is true steady-state, e. g. , when cruising on a motorway. Moreover, the most critical conditions encountered by industrial or marine engines are met during transients too. Unfortunately, the transient operation of turbocharged diesel engines has been associated with slow acceleration rate, hence poor driveability, and overshoot in particulate, gaseous and noise emissions. Despite the relatively large number of published papers, this very important subject has been treated in the past scarcely and only segmentally as regards reference books. Merely two chapters, one in the book Turbocharging the Internal Combustion Engine by N. Watson and M. S. Janota (McMillan Press, 1982) and another one written by D. E. Winterbone in the book The Thermodynamics and Gas Dynamics of Internal Combustion Engines, Vol. II edited by J. H. Horlock and D. E. Winterbone (Clarendon Press, 1986) are dedicated to transient operation. Both books, now out of print, were published a long time ago. Then, it seems reasonable to try to expand on these pioneering works, taking into account the recent technological advances and particularly the global concern about environmental pollution, which has intensified the research on transient (diesel) engine operation, typically through the Transient Cycles certification of new vehicles.
Author: IMECHE Publisher: CRC Press ISBN: 1000038262 Category : Technology & Engineering Languages : en Pages : 336
Book Description
With the changing landscape of the transport sector, there are also alternative powertrain systems on offer that can run independently of or in conjunction with the internal combustion (IC) engine. This shift has actually helped the industry gain traction with the IC Engine market projected to grow at 4.67% CAGR during the forecast period 2019-2025. It continues to meet both requirements and challenges through continual technology advancement and innovation from the latest research. With this in mind, the contributions in Internal Combustion Engines and Powertrain Systems for Future Transport 2019 not only cover the particular issues for the IC engine market but also reflect the impact of alternative powertrains on the propulsion industry. The main topics include: • Engines for hybrid powertrains and electrification • IC engines • Fuel cells • E-machines • Air-path and other technologies achieving performance and fuel economy benefits • Advances and improvements in combustion and ignition systems • Emissions regulation and their control by engine and after-treatment • Developments in real-world driving cycles • Advanced boosting systems • Connected powertrains (AI) • Electrification opportunities • Energy conversion and recovery systems • Modified or novel engine cycles • IC engines for heavy duty and off highway Internal Combustion Engines and Powertrain Systems for Future Transport 2019 provides a forum for IC engine, fuels and powertrain experts, and looks closely at developments in powertrain technology required to meet the demands of the low carbon economy and global competition in all sectors of the transportation, off-highway and stationary power industries.
Author: Federico Millo Publisher: Mdpi AG ISBN: 9783039361687 Category : Technology & Engineering Languages : en Pages : 324
Book Description
This Special Issue, consisting of 14 papers, presents the latest findings concerning both numerical and experimental investigations. Their aim is to achieve a reduction in pollutant emissions, as well as an improvement in fuel economy and performance, for internal combustion engines. This will provide readers with a comprehensive, unbiased, and scientifically sound overview of the most recent research and technological developments in this field. More specific topics include: 3D CFD detailed analysis of the fuel injection, combustion and exhaust aftertreatments processes, 1D and 0D, semi-empirical, neural network-based control-oriented models, experimental analysis and the optimization of both conventional and innovative combustion processes.
Author: Hideki Tsuge Publisher: CRC Press ISBN: 9814463108 Category : Medical Languages : en Pages : 378
Book Description
Microbubbles and nanobubbles have several characteristics that are comparable with millimeter- and centimeter-sized bubbles. These characteristics are their small size, which results in large surface area and high bioactivity, low rising velocity, decreased friction drag, high internal pressure, large gas dissolution capacity, negatively charged surface, and ability to be crushed and form free radicals. Microbubbles and nanobubbles have found applications in a variety of fields such as engineering, agriculture, environment, food, and medicine. Microbubbles have been successfully used in aquacultures of oysters in Hiroshima, scallops in Hokkaido, and pearls in Mie Prefecture, Japan. This field has shown a strong potential for growth. This book comprehensively discusses microbubbles and nanobubbles and their application in aquaculture, environment, engineering, medicine, stock raising, agriculture, and marine industry. It presents their potential as a new technology that can be utilized globally.
Author: Institution of Mechanical Engineers Publisher: Elsevier ISBN: 0857096044 Category : Technology & Engineering Languages : en Pages : 348
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: Yong Chuan Khoo
Author: Yong Chuan Khoo
Author: Camille Bilger
Author: Lulin Jiang
Author: 
Author: Alessandro Parente
Author: Constantine D. Rakopoulos
Author: IMECHE
Author: Federico Millo
Author: Hideki Tsuge
Author: Institution of Mechanical Engineers