Download or read book Investigation of the Effect of H D Ratio of a Novel Twin fluid Injection Concept on the Atomization and Combustion Performance written by Md Nayer Nasim and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation of Atomization Mechanisms and Flame Structure of a Twin fluid Injector for Different Liquid Fuels written by Lulin Jiang and published by . This book was released on 2014 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 (

Download or read book Investigation of the Combustion Performance of a Novel Twin fluid Fuel Injector on Different Liquid Fuels written by Oladapo S. Akinyemi and published by . This book was released on 2019 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Novel Combustion Concepts for Sustainable Energy Development written by Avinash K Agarwal and published by Springer. This book was released on 2014-12-19 with total page 561 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book comprises research studies of novel work on combustion for sustainable energy development. It offers an insight into a few viable novel technologies for improved, efficient and sustainable utilization of combustion-based energy production using both fossil and bio fuels. Special emphasis is placed on micro-scale combustion systems that offer new challenges and opportunities. The book is divided into five sections, with chapters from 3-4 leading experts forming the core of each section. The book should prove useful to a variety of readers, including students, researchers, and professionals.

Download or read book Atomization and Mixing Performance of Swirl venturi Lean Direct Injection written by Matthew W. Burkhalter and published by . This book was released on 2014 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper investigated the effects of swirl number and momentum ratio on the atomization and mixing performance of Swirl-Venturi Lean Direct Injection technology. Mie scattering of liquid water, was used to identify the location of water droplets in a cross section of the injector spray. Experiments were performed with three air swirlers with vane angles of 45, 52 and 60 degrees. The swirl number varied from 0.58 to 1.0 and air-to-liquid ratios from 15.8 to 35.6. A transition was observed in the liquid spray distribution for the 52 degree case, which unexpectedly produced twice as much signal than the 45 and 60 degree cases. The main cause of this increased signal may be due to instabilities in the flow when transitioning from low to high swirl states. The results from investigation of swirl number it was found that the spray pattern for is sensitive to swirl intensity. Two flow states were observed for a lower and higher swirl flow as well as a transition state that occurred with the lower swirl state. This work may aid in the specific inquiry of physical mechanisms relating to the effect of flow states on spray distribution. It is found that improved atomization and mixing performance are a result of increase in swirl number.

Download or read book An Experimental Investigation of Direct Injection for Homogeneous and Fuel stratified Charge Compression Ignited Combustion Timing Control written by Craig David Marriott and published by . This book was released on 2001 with total page 664 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Injection Atomization Ignition and Combustion of Liquid Fuels in High Speed Air Streams written by Joseph A. Schetz and published by . This book was released on 1982 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental studies of the penetration, break-up and atomization of transverse liquid and slurry jets were performed. All tests were with an air cross flow at Mach 3.0 with Po = 4 atm. and To = 300 deg K. The processes studied were: (1) the effects of injectant viscosity and surface tension, (2) the performance of an impinging jet injector and (3) the effects of particle loading for a slurry jet with 3-50 micrometer particles. The diffractively scattered light method was employed at these high-density, supersonic conditions to study droplet sizes. The major results are, (1) mean droplet size is approximately 10 microns for injectors of 0.05 in., (2) it has an inverse relation with jet/free stream dynamic pressure ratio, (3) it has a direct relation with orifice diameter, (4) it decreases downstream, (5) transverse variation has no simple pattern and (6) droplet size increases with viscosity.

Download or read book Liquid Atomization written by L.P. Bayvel and published by Routledge. This book was released on 2019-01-22 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covering the basics of liquid atomization, this book familiarizes readers with the physical processes of liquid atomization, the main types of atomizers and their design, measurements of spray characteristics, experimental investigations of atomizers, and application of atomizers. It demonstrates how to calculate and design atomizers and how to mea

Download or read book An Investigation on the Effects of the Liquid Fuel Injection Characteristics on Dual Fuel Engine Performance written by J. F. Smulders and published by . This book was released on 1952 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book AN EXPERIMENTAL STUDY ON THE IMPACT OF WATER INJECTION ON THE PERFORMANCE AND EMISSIONS OF A NATURAL GAS DIESEL PILOT ENGINE written by and published by . This book was released on 2022 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Natural gas has been gaining popularity as an alternative fuel due to its high availability, low CO2 emissions, and low cost. In this experimental study, water injection's impact on medium and heavy-duty engine operation fueled by natural gas and pilot diesel injection for ignition was studied under stochiometric operation for use with a three-way catalytic converter to meet criteria emissions for off-road power generation. To retain high efficiencies, a high compression ratio of 17.3:1 was used. Maintaining stoichiometric operation with a high compression ratio leads to combustion knock, pre-ignition, and high NOx formation. Conventionally, cooled EGR can be used to reduce NOx, but results in increased soot and does not eliminate combustion knock and pre-ignition. As an alternative to EGR this work utilized port injected water to provide on demand charge cooling, successfully reducing both NOx and soot while enabling high-load operation. A combination of both high and low speeds and loads were tested to study the impact of water injection on the emissions and performance of the natural gas, diesel-pilot engine. Additionally, water injections impact on diesel only operation was tested to provide comparison metrics and aid in a better understanding of the mechanisms at work when injecting water in an internal combustion engine. At full load, 16.8 bar BMEP, it was found that a water to fuel ratio of 0.5:1 was sufficient to enabling the knock free operation without significant increase in combustion duration or instability where operating at this load without water resulted in pre-ignition. Increasing the water to fuel ratio to 1:1 enabled a 21 bar BMEP load. At 12.5 bar BMEP, the NOx emission was reduced from 13.5 g/kwh to 7.2 g/kwh with a water to fuel mass ratio of 1.5:1. In addition to solving the high NOx and pre-ignition problem, a water to fuel ratio of 2.5:1 at 16.8 bar BMEP also decreased the soot content in the exhaust by a factor of 3.5 with only a small penalty in efficiency, decreasing break thermal efficiency from 41 to 40%.

Download or read book Flow Independent Fuel Injection for More Consistent Liquid Combustion Using Pintile Injectors written by Charles Clark and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Liquid jet in crossflow systems are often used as lightweight and efficient mechanisms of atomizing fuel prior to entertainment in the flame holder and combustion, making them integral components of liquid fueled engines. Unfortunately, such systems are susceptible to deviations in both trajectory and breakup rate, depending primarily on the Weber number and momentum flux ratio of the injected jet. In these studies, the effects of solid obstructions, called pintiles, on the variability of liquid jet in cross flow trajectory and breakup are investigated. Initial investigations looked at the impacts of broad geometric parameters on flow independence, using Mie scatter imaging and phase Doppler particle analysis. The results of that investigation yielded an optimal overarching geometry for pintiles. This knowledge was then refined by looking at specific face characteristics of the obstructions, primarily investigating face angle and concavity. Spray characteristics were spatially resolved using LIF/Mie particle sizing techniques, revealing that modest convex surfaces yielded the most consistent breakup characteristics across space, while simultaneously improving the average breakup distance of the liquid jet. Finally, this progression of pintile characteristics is investigated on the effects pintiles have on overarching flame properties, using C2*/CH* chemiluminescence ratios to determine spatially resolved equivalence ratio distributions across a wide range of Weber numbers and momentum flux ratios encompassing breakup regimes from the enhanced capillary modes through to shear breakup modes. Results from these studies demonstrate significant improvement of combustion properties from the introduction of the pintiles.

Download or read book Fundamentals of Fuel Injection and Emission in Two Stroke Engines written by Wadysaw Mitianiec and published by Nova Science Publishers. This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main goal of the book is the presentation of the last theoretical and experimental works concerning fuel injection systems, mainly in small power two-stroke engines as well as in marine engines. This book includes thirteen chapters devoted to the processes of fuel injection and the combustion that takes place in a stratified charge within the cylinders of two-stroke engines. In the first two chapters, the division into different injection systems in two-stroke engines and each injection system is briefly described. Various theoretical and practical solutions of fueling system designs are described. In Chapter Three, mathematical models, the spatial movement of gas in the cylinder and the combustion chamber are introduced, taking into account the turbulence of the charge. Chapter Four relates to the behavior of fuel injected into the gaseous medium, including evaporation processes, disintegration and processes occurring while the fuel drops connect with the wall. The next section describes the zero-dimensional model of fuel injection in two-stroke engines along with examples of numerical calculations. The sixth chapter is devoted to CFD multi-dimensional models of movement and evaporation of the fuel in a closed gaseous medium, occurring also in other engine types. Chapter Seven describes a two-zone model of the combustion process and the effect of the geometry of the combustion chamber on the flame propagation with a simplified verification model of combustion. Chapter Eight compares the propagation phase of gas and liquid fuels concerning direct fuel injection as well as the direct fuel injection from the cylinder head and the thermodynamic parameters of the charge. The formation of the components during the combustion process in the direct fuel injection two-stroke engine was obtained by numerical calculations and results are discussed in Chapter Nine. Chapter Ten describes the parameters of the two-stroke engine with a direct fuel injection carried out at the Cracow University of Technology. Additionally, the chapter presents CFD simulations of fuel propagation and combustion processes, taking into account the formation of toxic components and exhaust gas emission. The processes of two direct rich mixture injection systems FAST and RMIS developed in CUT are presented in Chapter Eleven. Miscellaneous problems of direct fuel injection, such as characteristics of fuel injectors, problems of direct gaseous fuel injection, and the application of fuelling systems in outboard engines and snowmobile vehicles are presented in Chapter Twelve. A comparison of working parameters in two- and four stroke engines is also mapped out. The last chapters contain the final conclusions and remarks concerning fuel injection and emission of exhaust gases in small two-stroke engines. This book is a comprehensive monograph on fuel injection. The author presents a series of theoretical and design information from his own experience and on the basis of the works of other authors. The main text intends to direct fuel injection with respect to gas motion in the combustion chamber and influence the injection parameters for exhaust emission. The book presents its own theoretical work and experimental tests concerning a two-stroke gasoline engine with electrically controlled direct fuel injection. The book describes the processes of a general nature also occurring in other types of engines and presents a comparison of different injection systems on working parameters and gas emission. The book contains 294 images, 290 equations and 16 tables obtained from the CFD simulation and experimental works.

Download or read book Numerical Investigation of the Effect of In cylinder Flow on Combustion and Emissions of a Direct Injection Diesel Engine written by Reza Rezaei and published by . This book was released on 2011 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Comprehensive Study of Internal Flow Field and Linear and Nonlinear Instability of an Annular Liquid Sheet Emanating from an Atomizer written by Ashraf Ibrahim and published by . This book was released on 2006 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: Performance of fuel injectors affects the combustion efficiency, pollutant emissions and combustion instability in gas turbine engines, internal combustion engines and industrial furnaces. In these combustion systems, either pressure swirl (simplex) atomizers, or prefilming airblast atomizers, or plain orifice pressure atomizers are used for fuel atomization. In this dissertation, a comprehensive model for pressure-swirl atomization is developed that includes computational treatment of the internal flow field and the nonlinear liquid sheet instability analysis for primary breakup. For a prefilming airblast atomizer and a plain orifice atomizer, nonlinear breakup processes for an annular liquid sheet and a liquid jet are analyzed using a perturbation method. Two-dimensional axi-symmetric numerical simulations have been carried out to study the unsteady, turbulent, swirling two-phase flow field inside pressure swirl atomizers with the volume of fluid (VOF) method. Internal flow field simulation results are validated using available experimental data for velocity measurements inside a large-scale prototype atomizer, the film thickness at orifice exit, the spray angle, and the discharge coefficient. The effect of air pressure and liquid viscosity on flow field inside the atomizer is investigated. The relationship between the internal flow characteristics and discharge parameters confirms that the internal flow structure plays a very important role in determining the atomizer performance. Linear and nonlinear asymmetric instability analyses are carried out to study the primary atomization of annular liquid sheets and liquid jets emanating from the pressure swirl (simplex) atomizer, prefilming airblast atomizer, and plain orifice pressure atomizer using a perturbation method with the initial amplitude of the disturbance as the perturbation parameter. For a coaxial liquid jet subjected to a swirling gas stream, the axisymmetric disturbance mode (n = 0) is the most dominant only when the gas swirl number is very small. However at higher swirl strength the helical (asymmetric) disturbance modes (n> 0) become dominant compared to the axisymmetric mode. The liquid jet breaks up over a shorter distance at higher gas swirl number. The gas swirl number for transition to a highly asymmetric breakup with a high circumferential wave number (n = 5) is found to vary as the inverse of the square root of the gas-to-liquid momentum ratio when the gas-to-liquid momentum ratio is less than 1. For annular liquid sheets, the breakup length is reduced by an increase in the liquid Weber number, initial disturbance amplitude and the inner and outer gas-liquid velocity ratios. The inner gas stream is found to be more effective in disintegrating and enhancing the instability of annular liquid sheets than the outer gas stream. Air swirl not only promotes the instability of the annular liquid sheet, but also switches the dominant mode from the axisymmetric mode to a helical mode (n> 0). As outer air swirl strength increases, the circumferential wave number (n) increases and the ligament shapes at the breakup time become highly asymmetric. Using the atomizer exit conditions as input, a non-linear sheet instability and breakup analysis has been carried out to predict the breakup length and the primary breakup for a simplex atomizer. The predictions of breakup length are compared with available experimental measurements which show good agreement. The coupled internal flow simulation and nonlinear sheet instability analysis provides a comprehensive approach to modeling atomization from a pressure-swirl atomizer.

Download or read book Investigations of Advanced Injection and Combustion Strategies in Low emissions Diesel Engines written by Sage L. Kokjohn and published by . This book was released on 2008 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Investigation of the Effects of Water Injection in an Internal Combustion Engine written by Embry D. Faatz and published by . This book was released on 1934 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Analysis of Mixture Formation and Combustion in a Hydrogen Direct Injection Internal Combustion Engine written by Udo Gerke and published by Cuvillier Verlag. This book was released on 2008-02-05 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present work investigates the mixture formation and combustion process of a direct-injection (DI) hydrogen internal combustion engine by means of three-dimensional numerical simulation. The study specifies details on the validity of turbulence models, combustion models as well as aspects on the definition of hydrogen-air burning velocities with respect to hydrogen IC engine applications. Results of homogeneous, stratified and multi-injection engine operation covering premixed, partially premixed and non-premixed combustion of hydrogen are presented. Results of the numerical simulations are validated using data of experimental analysis from parallel works, employing a one-cylinder research engine and a research engine with optical access. As a fundamental contribution to combustion modelling of hydrogen IC engines, a new correlation for laminar burning velocities of hydrogen-air mixtures at engine-relevant conditions is derived from measurements of premixed outwards propagating flames conducted in a single-cylinder compression machine. Numerical results of the direct-injection mixture formation give a detailed understanding of the interrelation between injection timing and the degree of mixture homogenisation. A favourable agreement between the computed fuel concentration and results of Planar Laser Induced Fluorescence (PLIF) measurements is reported for various injection timings. Different two-equation turbulence models, a Shear Stress Transport (SST) model and a k-ε model based on Renormalisation Group (RNG) theory as well as a Reynolds Stress Model (RSM) are discussed. The impact of the models on the level of turbulent kinetic energy proves to be of major importance. State-of-the-art turbulent combustion models on the basis of turbulent flame speed closure (TFC) and on the basis of a flame surface density approach, the Extended Coherent Flame Model (ECFM), are examined. The models are adapted to hydrogen internal combustion engines and are interfaced to the established three-dimensional flow field solver ANSYS CFX within the framework of the international research project HyICE. Two different approaches are investigated as input for the laminar burning velocities of hydrogen. Firstly, flame speed data are computed with a kinetic mechanism. Secondly, an existing experimentally derived laminar flame speed correlation is extended to rich air/fuel equivalence ratios (λ 1) and is compared to measurements conducted within the present work. In general, the TFC-models show a satisfying agreement for DI operating points compared to experimental data, when mixing computations are conducted with the SST turbulence model. Also, port fuel injection (PFI) operating points demonstrate a good performance with these models, however, the constant model prefactor (multiplier for the closure of turbulent flame speed) has to be defined individually for PFI and DI computations. This effect might be caused by the dissimilar sources of turbulence for the two engine types (PFI and DI) which cannot be adequately predicted by the turbulence models. Combustion computations on the basis of mixture results obtained by the RNG-model generally underrate the level of turbulence intensity for stratified operation points, effecting too weak rates of heat release. The ECFM combustion model shows a satisfying predictability for the PFI case using a constant model prefactor. Computations of DI operating points with this model, however, require a readjustment of the prefactor for each operating point in order to match experimental results. Regarding turbulent combustion, the hydrogen laminar flame speed is recognised to be the crucial quantity for the employed modelling approaches. Since direct-injection hydrogen engines in the stratified case engender a wide range of equivalence ratios, fundamental data for the laminar flame speed has to be provided as a model input within the entire boundaries of ignition limits. A lack of experimental data of laminar flame speed at engine-relevant conditions (high pressure, high temperature) is noticed. In order to perform a detailed study on hydrogen burning velocities, a single-cylinder compression machine is selected to conduct flame speed measurements of hydrogen-air mixtures at ignition temperatures and pressures up to T = 700 K and p = 45 bar, considering air/fuel equivalence ratios between λ = 0.4 and 2.8. Flame front velocities are acquired by means of optical methods using OH-chemiluminescence and thermodynamic, multi-zone evaluation of pressure traces. In comparison to data of laminar flame speed derived from reaction mechanisms and flame speed correlations found in literature, the experimental results show increased burning velocities due to flame front wrinkling caused by hydrodynamic and thermo-diffusive instabilities. a href="http://ec.europa.eu/research/transport/news/article_5199_en.html" EU Transport Research