Download or read book Investigation of Near field Spray Characteristics of Alternative and Conventional Jet Fuels Using a Twin fluid Atomizer written by Imtiaz Qavi 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 Spray Characteristics of Two Novel Twin fluid Fuel Atomizers written by Vu Tuan Danh and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Jet Fuel Spray Characterisation Using Optical Methods written by Rami Zakaria and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book An Investigation of the Spray Characteristics of a Boiler Fuel Oil Atomizer written by Joseph Berwick Duval and published by . This book was released on 1939 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Liquid Jet in Oscillating Crossflow written by Arvindh R. Sharma and published by . This book was released on 2015 with total page 139 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation of response characteristics of a liquid jet in oscillating crossflow is undertaken to understand the behavior of a liquid fuel spray in the presence of combustion instabilities. The effect of crossflow oscillations on the liquid jet is studied in the near-field (within x/d[approximately equal]8) and the far-field (x/d[approximately equal]50) spray region. Experiments are conducted in bag breakup, multimode and shear breakup regimes by varying crossflow Weber number from 18 to 250, while momentum flux ratio is varied between 10 and 30. The crossflow is modulated in the frequency range of 90 Hz to 450 Hz, with modulation level varying between 5% and 20%, using a mechanical modulating device. High speed shadowgraph is employed to study the near-field and far-field spray movement while intensified high-speed camera images of laser Mie-scattering intensity are utilized in studying the spray cross-section in the far-field. A technique to extract time-varying momentum flux ratio from the windward trajectory of liquid jet in the near-field is developed. The response of near-field spray is quantified in terms of a ratio of the observed momentum flux ratio extracted from a correlation of upper penetration to the expected momentum flux ratio corresponding to the instantaneous crossflow velocity. The liquid jet penetration is found to respond to oscillations in the crossflow at all oscillation frequencies in the near-field. The strength of the response is found to be mainly dependent on the crossflow oscillation frequency, with the strength of response decreasing with increase in frequency. The momentum flux ratio and the modulation level are found to have relatively negligible effects on the level of normalized spray response. The spray response in the far-field is studied by observing the high-speed shadowgraphs and Mie-scattering intensity images at an axial distance of x/d=50. The spray field in the axial location is divided into ten bins and the intensity change in each bin is analyzed to quantify spray response. The spray is found to respond to crossflow oscillations by exhibiting a "flapping" behavior in the far-field. The binning method and Mie-scattering intensity image analysis suggest that the spray oscillation decreases with increasing crossflow frequency. The spray width and height fluctuate in the spray cross-section in the presence of crossflow oscillation. The amplitude of spray height fluctuation is higher in low frequency crossflow, and decreases with an increase in frequency. The total Mie-scattering intensity in the cross-section also exhibits a periodic response to crossflow oscillation, suggesting that the droplet characteristics are affected by crossflow fluctuation. The liquid spray near-field and far-field study indicates that the crossflow oscillation frequency plays a large role in determining spray response.

Download or read book Investigation of Spray Characteristics for Flashing Injection of Fuels Containing Dissolved Air and Superheated Fuels written by A. S. P. Solomon and published by . This book was released on 1982 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effect of Ambient Pressure on the Spray Characteristics of a Twin fluid Atomizer written by S. A. Drennan and published by . This book was released on 1990 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A combined simplex/air-assist atomizer with swirl is characterized in an isothermal high pressure spray characterization chamber, with optical access, under various ambient pressures. A single-component, phase Doppler laser interferometer is used to obtain spatially resolved droplet size and velocity information. Data are obtained at atmospheric pressure as well as 3 and 6 atmospheres for conditions of constant fuel and atomizing air flow rates. Two different nozzle air flow rates and, hence, two different air-to-liquid ratios are considered. Increasing ambient pressure decreases the air-to-liquid momentum ratio and thereby decreases droplet mean axial velocity and increases the droplet size. The response of a spray to increasing ambient pressure is sensitive to the parameters which are held constant while increasing ambient pressure. The appropriate scaling parameters for the extrapolation of atmospheric testing data to high ambient pressures are likely geometry specific, and will require data of the type reported here.

Download or read book Atomization and Sprays written by Arthur H. Lefebvre and published by CRC Press. This book was released on 2017-03-27 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: The second edition of this long-time bestseller provides a framework for designing and understanding sprays for a wide array of engineering applications. The text contains correlations and design tools that can be easily understood and used in relating the design of atomizers to the resulting spray behavior. Written to be accessible to readers with a modest technical background, the emphasis is on application rather than in-depth theory. Numerous examples are provided to serve as starting points for using the information in the book. Overall, this is a thoroughly updated edition that still retains the practical focus and readability of the original work by Arthur Lefebvre.

Download or read book Experimental Investigation of Pressure swirl Atomizer Spray Stability with Addition of a Pre filming Surface written by Ethan Hanson and published by . This book was released on 2020 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: "In a combustion environment, system instabilities and dynamic responses of components can have a major influence on performance, emissions, and product life. One of the key components in a combustion system are the fuel injectors which utilize instabilities to generate a well atomized fuel spray. In this work, a pressure-swirl atomizer was studied under steady state operation and oscillating pressure differential conditions to simulate a dynamic system input to the atomizer. Atomizer spray with and without the addition of a pre-filming surface was evaluated to determine the influence that a pre-filming surface has on the dynamic response of the liquid sheet near the atomizer exit. High-speed video was utilized to capture the response of the liquid sheet and quantify the instability. It was found that under steady state operating conditions, the pre-filming surface increased the atomizer flow number and discharge coefficient. When comparing spray edge variation, the atomizer without a pre-filming surface demonstrated an increasing spray edge variation with increasing pressure while the opposite trend was observed in the atomizer with a pre-filming surface. Under conditions with an oscillating pressure differential, additional spray edge variation was observed near field of the atomizer exit but was nonexistent further downstream indicating that the superposition of the fluid from pressure oscillation dissipated as it moved further from the atomizer exit and did not have an impact on wave growth in the liquid sheet."--Abstract.

Download or read book Comparing Spray Characteristics from Reynolds Averaged Navier Stokes Rans National Combustion Code Ncc Calculations Against Experimental Data for a Turbulent Reacting Flow written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-20 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: Developing physics-based tools to aid in reducing harmful combustion emissions, like Nitrogen Oxides (NOx), Carbon Monoxide (CO), Unburnt Hydrocarbons (UHC s), and Sulfur Dioxides (SOx), is an important goal of aeronautics research at NASA. As part of that effort, NASA Glenn Research Center is performing a detailed assessment and validation of an in-house combustion CFD code known as the National Combustion Code (NCC) for turbulent reacting flows. To assess the current capabilities of NCC for simulating turbulent reacting flows with liquid jet fuel injection, a set of Single Swirler Lean Direct Injection (LDI) experiments performed at the University of Cincinnati was chosen as an initial validation data set. This Jet-A/air combustion experiment operates at a lean equivalence ratio of 0.75 at atmospheric pressure and has a 4 percent static pressure drop across the swirler. Detailed comparisons of NCC predictions for gas temperature and gaseous emissions (CO and NOx) against this experiment are considered in a previous work. The current paper is focused on detailed comparisons of the spray characteristics (radial profiles of drop size distribution and at several radial rakes) from NCC simulations against the experimental data. Comparisons against experimental data show that the use of the correlation for primary spray break-up implemented by Raju in the NCC produces most realistic results, but this result needs to be improved. Given the single or ten step chemical kinetics models, use of a spray size correlation gives similar, acceptable results Iannetti, Anthony C. and Moder, Jeffery P. Glenn Research Center COMPUTATIONAL FLUID DYNAMICS; TURBULENT FLOW; SPRAY CHARACTERISTICS; JET ENGINE FUELS; REACTION KINETICS; HYDROCARBONS; SULFUR DIOXIDES; NITROGEN OXIDES; EXHAUST EMISSION; FUEL INJECTION; STATIC PRESSURE; SIMULATION; GAS TEMPERATURE; EXHAUST GASES

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 Investigation of Spray for Characteristics for Flashing Injection of Fuels Containing Dissolved Air and Superheated Fuels written by A. S. P. Solomon and published by . This book was released on 1982 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Path to the Formulation of New Generations of Synthetic Jet Fuel Derived from Natural Gas written by Ibrahim Awni Omar Hassan Al-Nuaimi and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Characterization of jet fuels obtained from sources other than crude oil is a modern area of research that is developing continuously to replace available petroleum-based fuels with 'drop-in' alternative fuels. Therefore, reliable composition-property relations are developed to correlate the hydrocarbon compositions of formulated synthetic fuels with their properties to be certified for aviation commercial use. Intensive studies have been initiated at Texas A&M University Qatar in collaboration with industry and academia to study synthetic jet fuels derived from natural gas. These studies are being implemented at its Fuel Characterization Lab where the most advanced testing equipment is used and strict Quality Management and safety systems are followed. This study is divided into two tracks. The first track is focused on conducting experimental investigations using in-house formulated synthetic jet fuels derived from natural gas via Gas-to-Liquid technology and Fischer-Tropsch chemistry. Throughout this research work, these fuels will be referred to as Synthetic Paraffinic Kerosene (SPK). These experimental investigations activities are composed of three phases: the first phase focuses on the influence of SPK building blocks (paraffinic hydrocarbons) on fuels' properties, the second phase concerns evaluating the role of aromatics and cyclo-paraffins on properties, and the third phase studies the influence of mixing SPK with conventional Jet A-1 derived from crude oil. All of the aforementioned experimental investigations are aimed at building an experimental data bank to assist the efforts of the formulation of new generations of SPKs that meet aviation industry standards. On the other hand, the second track is directed towards the development of mathematical correlations for four properties of high importance to SPK certification. These correlations aim at optimizing fuel composition whereby major physical/chemical properties of ASTM D1655 are met at the lowest cost of composed fuel. The primary findings of this study showed that GTL derived SPK paraffinic constituents can improve certain properties while affecting others negatively, and emphasizing the necessity of aromatics in improving specific properties. Further studies compensating the absence of aromatics and sulfur through blended Jet A-1 revealed a practical solution through jet fuels optimization based on cost and technical effective manners. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/150984

Download or read book Measuring Method for the Spray Characteristics of a Fuel Atomizer at Various Conditions of the Ambient Gas written by Kiyoshi Neya and published by . This book was released on 1967 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation on the Role of Atomization Air Mixing on the Spray Characteristics of Air Assisted Atomizer written by Noritsune Kawaharada and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Investigation of Spray Atomization Properties of an Aircraft Engine Swirl Cup written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Five cases are examined in which a spray field generated by a commercial simplex nozzle is influenced by the counter-rotating flow structure created by a production CFM56 swirl cup. The first case involving water atomization at an equivalence ratio of 0.7 and an air temperature of 100ʻF acts as the baseline for this study. Subsequent cases assess the effects of different liquids, water or Jet-A fuel, of different equivalence ratios, 0.7 or 1.1, and different air temperatures, 100ʻF or 400ʻF. Digital images employing a laser sheet offer some qualitative flow visualization of the spray. In addition, measurements are conducted with a two-dimensional Phase Doppler Particle Analyzer system within close proximity to the swirl cup exit plane, which provides the three principle orthogonal velocities and a diameter distribution throughout the spray field. Combined, this information provides insight to the characteristics of liquid spray behavior and its sensitivity to varying these parameters.