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Investigation On The Internal Flow Characteristics Of Pressure Swirl Atomizers
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Book Synopsis Investigation on the Internal Flow Characteristics of Pressure-swirl Atomizers by : Zhanhua Ma
Download or read book Investigation on the Internal Flow Characteristics of Pressure-swirl Atomizers written by Zhanhua Ma and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The performance of liquid fuel atomizer in gas turbine combustor has direct effects on flame stability, combustion efficiency, and pollutant emissions. Therefore, further understanding of the underlying physics of these atomizers is one of the primary requirements for advanced gas turbine combustor design. Simplex atomizers are commonly used in air-breathing gas turbine engines because they produce good atomization characteristics and are relatively simple and inexpensive to manufacture. Internal flow characteristics of simplex nozzles play a very important role on the atomizer performance. So it is of great practical interest to examine the relationships between internal flow characteristics, nozzle design variables, and important spray features. Part I of this dissertation revealed the detailed flow structure inside simplex atomizers through the DPIV and LDV study. The internal flow field is generally symmetric except very near the inlet slot plane. The velocity profiles are very similar at different axial locations within the swirl chamber. The discharge parameters were measured and used to examine the correlations from previous researchers. Detailed flow field information was linked with the discharge parameters to obtain more insight into the nozzle performance. The relationship between the internal flow characteristics and discharge parameters confirmed that the internal flow structure plays a very important role on the atomizer performance. Part II presents the internal flow structure of large-scale simplex nozzles at two different working-fluid/ambient-fluid density ratios. The effects of density ratio, Reynolds number and orifice geometry on the internal flow field were examined by using a 2-D LDV probe. At the higher density ratio, Reynolds number and orifice geometry has little impact on the internal flow field. At the lower density ratio, the orifice contraction angle has little effect on the internal flow field, whereas the expansion angle can significantly affect the internal flow structure. A dominant frequency was found from the velocity frequency analysis, which indicates that the internal flow is controlled by certain dominant frequency. A dimensionless dominant frequency, similar to the Strouhal number in the flow past a cylinder, was defined using the orifice diameter and mean axial velocity in the orifice. In the part III of this dissertation, the internal flow field of the simplex atomizer with macrolaminated geometry was measured by using the refractive index matching fluid method and DPIV system. In the swirl chamber, the liquid flow is unsteady and exhibits 3-D features, which is more evident as the flow rate increases. In the orifice, the liquid flow is more uniform and axisymmetrical. The discharge parameters were measured and compared with the correlations from previous researchers.
Book Synopsis Computational Simulation of Flow Inside Pressure-swirl Atomizers by :
Download or read book Computational Simulation of Flow Inside Pressure-swirl Atomizers written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Simplex atomizers (pressure-swirl atomizers) are widely used in air-breathing gas turbine engines as they have good atomization characteristics and are relatively simple and inexpensive to manufacture. To reduce emissions, it is critical to design fuel atomizers that can produce spray with a predetermined droplet size distribution at the desired combustor location (small mean droplet diameters and uniform local air/fuel ratios). Manufacturing methods are now available where complex atomizer geometries can be easily obtained. However to use such methods, the influence of atomizer geometry on its performance must be well understood. In this dissertation, a two-dimensional axisymmetric computational fluid dynamics (CFD) model based on the Arbitrary-Lagrangian-Eulerian (ALE) method to predict the flow in pressure-swirl atomizers was developed. The Arbitrary-Lagrangian-Eulerian method was applied so that the free interface between gas and liquid could be tracked sharply and accurately. The developed code was validated by comparison of predictions with experimental data for large scale prototype and with semi-empirical correlations at small scale. The computational predictions agreed well with experimental data for the film thickness at the exit, spray cone angle, and the pressure drop across the atomizer as well as velocity field in the swirl chamber. Using the validated code, a comprehensive parametric study on simplex atomizer performance was conducted. The geometric parameters of atomizer covered in this study include: atomizer constant, the ratio of length to diameter in swirl chamber, the ratio of length to diameter in orifice, the swirl chamber to orifice diameter ratio, inlet slot angle, trumpet angle, trumpet length, and swirl chamber convergent angle. The effects of these geometric parameters on the atomizer performance were studied for a fixed mass flow rate through the atomizer as well as for a fixed pressure drop across the atomizer. The atomizer performance was described in term of dimensionless film thickness at the exit, discharge coefficient and spray cone half angle. To address applications in pharmaceutical and food processing industry, flow of non-Newtonian power-law fluids through pressure-swirl atomizers was considered. Detailed flow patterns inside the atomizer for shear-thinning, Newtonian and shear-thickening fluids were investigated. A range of power-law index from 0.7 to 1.3 was considered. With a fixed flow rate through the atomizer, the shear-thickening fluids exhibited higher film thickness at exit, lower spray angle, and higher discharge coefficient compared to Newtonian fluids. For the range of power-law index considered in this study, the atomizer performance parameters for shear-thinning fluids showed small change from Newtonian fluids. The variation of atomizer performance with the atomizer constant was delineated for different power-law index.
Book Synopsis An Investigation Into the Applicability of Commonly Used Evaluative Expressions in Swirl Atomizers for Cryogenic Conditions by : Troy Martin Jonathan Kuersten
Download or read book An Investigation Into the Applicability of Commonly Used Evaluative Expressions in Swirl Atomizers for Cryogenic Conditions written by Troy Martin Jonathan Kuersten and published by . This book was released on 2017 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this thesis was to determine the validity of the expression developed by Rizk and Lefebvre in their seminal 1985 paper ???Internal Flow Characteristics of Simplex Swirl Atomizers??? for use in applications using cryogenic fluids as well as its common modifications. Since the hybrid rocketry applications of swirl atomizers most often involve such fluids, it is vital to determine whether a commonly used analytical expression remains valid in those circumstances. A computation fluid dynamics (CFD) simulation was performed, first using water as a working fluid to determine a baseline of accuracy that could be expected, then using liquid oxygen as a working fluid to determine the accuracy of the expression to a cryogenic case. In addition, experimental data from several papers using both room temperature and cryogenic fluids were examined; both to expand the data from which to draw a baseline and to expand the data from which to analyze the performance of cryogenic working fluids. The CFD simulation was run at a pressure of 1 kPa with a geometry similar to those commonly used in hybrid rocket applications. While the results diverged significantly from those of the analytical expressions, the water and liquid oxygen cases showed similar divergence, indicating a similar level of accuracy in prediction. As a secondary result, the low suitability of these expressions for analysis of atomizers significantly larger than those used in the initial development of the relation and at lower pressure was shown. The experimental data provided a baseline of ??20% accuracy of the expressions with regard to the empirical results for the room temperature fluids. Using that baseline, it was shown that the analysis of the case with a cryogenic fluid was accurate to within a similar tolerance.
Book Synopsis Handbook of Atomization and Sprays by : Nasser Ashgriz
Download or read book Handbook of Atomization and Sprays written by Nasser Ashgriz and published by Springer Science & Business Media. This book was released on 2011-02-18 with total page 922 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atomization and sprays are used in a wide range of industries: mechanical, chemical, aerospace, and civil engineering; material science and metallurgy; food; pharmaceutical, forestry, environmental protection; medicine; agriculture; meteorology and others. Some specific applications are spray combustion in furnaces, gas turbines and rockets, spray drying and cooling, air conditioning, powdered metallurgy, spray painting and coating, inhalation therapy, and many others. The Handbook of Atomization and Sprays will bring together the fundamental and applied material from all fields into one comprehensive source. Subject areas included in the reference are droplets, theoretical models and numerical simulations, phase Doppler particle analysis, applications, devices and more.
Book Synopsis Investigation of the Flow Pattern Within and at the Exit of a Pressure Swirl Atomizer by : Konstantinos Vamvakoglou
Download or read book Investigation of the Flow Pattern Within and at the Exit of a Pressure Swirl Atomizer written by Konstantinos Vamvakoglou and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Advances in Engineering Design and Simulation by : Chenfeng Li
Download or read book Advances in Engineering Design and Simulation written by Chenfeng Li and published by Springer Nature. This book was released on 2019-10-03 with total page 345 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book consists of selected peer-reviewed papers presented at the NAFEMS India Regional Conference (NIRC 2018). It covers current topics related to advances in computer aided design and manufacturing. The book focuses on the latest developments in engineering modelling and simulation, and its application to various complex engineering systems. Finite element method/finite element analysis, computational fluid dynamics, and additive manufacturing are some of the key topics covered in this book. The book aims to provide a better understanding of contemporary product design and analyses, and hence will be useful for researchers, academicians, and professionals.
Book Synopsis Energetic Materials Research, Applications, and New Technologies by : Goncalves, Rene Francisco Boschi
Download or read book Energetic Materials Research, Applications, and New Technologies written by Goncalves, Rene Francisco Boschi and published by IGI Global. This book was released on 2017-12-29 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last decade, there has been an influx in the development of new technologies for deep space exploration. Countries all around the world are investing in resources to create advanced energetic materials and propulsion systems for their aerospace initiatives. Energetic Materials Research, Applications, and New Technologies is an essential reference source of the latest research in aerospace engineering and its application in space exploration. Featuring comprehensive coverage across a range of related topics, such as molecular dynamics, rocket engine models, propellants and explosives, and quantum chemistry calculations, this book is an ideal reference source for academicians, researchers, advanced-level students, and technology developers seeking innovative research in aerospace engineering.
Book Synopsis Atomization and Sprays by : Arthur H. Lefebvre
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.
Book Synopsis Comprehensive Study of Internal Flow Field and Linear and Nonlinear Instability of an Annular Liquid Sheet Emanating from an Atomizer by : Ashraf Ibrahim
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.
Book Synopsis The Internal Flow Field of a Pressure Swirl Atomizer by : Dennis Cooper
Download or read book The Internal Flow Field of a Pressure Swirl Atomizer written by Dennis Cooper and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Theory and Practice of Swirl Atomizers by : Yuriy I Khavkin
Download or read book Theory and Practice of Swirl Atomizers written by Yuriy I Khavkin and published by CRC Press. This book was released on 2003-10-28 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book, prominent Russian scientist Yuriy I. Khavkin shows that the droplet sizes in swirl atomizers depend only on the specific energy of the liquid drops and on viscosity. The new theory based only on two parameters is shown to be far simpler and in better agreement with experimental data than any previous presentations. The following topics are included in the book: · The solution of the Navier-Stokes equation for a liquid rotating flow · Atomizers for gas turbine combustion chambers · Atomizers for high capacity steam boilers · Atomizers for liquid-propellant rocket engines · Quality of liquid atomization by non-swirl atomizers · A unique table of experimental data of 232 atomizers, enables the reader to find an atomizer with the flow rate from 5 kg/h to 15,000 kg/h Readers will also learn: · To create an atomizer with the given mean droplet size · To create an atomizer with the given droplet size distribution · To create an atomizer with the given limits of flow rate control. The book is intended for the design engineer, as well as the theoretical scientist.
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 Paper written by and published by . This book was released on 1998 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Proceedings of First International Conference on Emerging Trends in Mechanical Engineering by :
Download or read book Proceedings of First International Conference on Emerging Trends in Mechanical Engineering written by and published by Universal-Publishers. This book was released on with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Internal Fluid Mechanics of an Effervescent Atomizer by : Miguel A. Balzán
Download or read book Internal Fluid Mechanics of an Effervescent Atomizer written by Miguel A. Balzán and published by . This book was released on 2015 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation was conducted with the purpose of studying the effects of selected operating and design variables in the flow inside an effervescent atomizer. A series of tests were performed in a horizontally oriented, square conduit of 12.7 mm in diameter which constituted the mixing chamber of the effervescent atomizer. The operating fluids were water and air. The air was injected perpendicularly into a fully developed, turbulent water flow, whose bulk water velocity values ranged between 1.1 and 4.3 m/s. The gas mass flow rate values were in the range between 8 and 60 × 10-3 g/s. Three different gas injectors, with diameters of 0.27 mm, 0.52 mm and 1.59 mm were used. The combination of variables allowed the operation of the atomizer within the limits of what constitutes a bubbly flow in pipes. High-speed shadowgraphy was the technique used to investigate thoroughly the dynamics between the gas and liquid phases near the gas injection region as well as upstream the discharge nozzle. A set of original, empirical expressions used to estimate the incipient centerline and borderline trajectories of the gas phase, during its initial interaction with the liquid and based on dimensionless parameters, were introduced. The assessment of the correlations gave a strong prediction of the initial centerline and borderline trajectories of the gas jet in the flowing liquid. The effects that the gas injection velocity, liquid mean velocity and injection gas injection diameter have on the process of bubble generation were investigated. Four distinct regimes were identified: Single Bubbling (SB), Pulse (P), Elongated Jetting (EJ) and Atomizing Jetting (AJ). It was observed that the shift between regimes occurs gradually, producing the need to identify transitional regions: SBP and PTJ. Sets of independent dimensionless variables were used to categorize the proposed regimes in bubble formation maps. Empirical correlations that delimit the boundaries between ordered and chaotic bubble generation were determined. An introductory description of the forces involved in the bubbling process was conducted. The results indicated that the form-induced drag and added mass force were dominant detaching and cohesive force respectively. While there was agreement with previous works regarding the dominant breakup effect, the results obtained for the main attaching force were unique. Also, a novel methodology for the estimation of dynamic shape based drag and added mass coefficient was included. The morphological features of the gas jet were described through empirical correlations based on relevant dimensionless numbers associated to the variations of three fundamental design parameters: liquid cross-flow velocity, gas mass flow rate and the nozzle dimensions. The gas jet features were compared with representative statistical diameters from the population distribution, resulting in an estimation of the averaged Sauter mean diameter and maximum bubble diameter as a function of the gas jet dimensions. It was determined that the gas injection conditions play a fundamental role in the internal flow characteristics for an effervescent atomizer.
Book Synopsis Advances in Design and Thermal Systems by : Lionel Ganippa
Download or read book Advances in Design and Thermal Systems written by Lionel Ganippa and published by Springer Nature. This book was released on 2021-04-21 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book presents the select peer-reviewed proceedings of the International Conference on Emerging Trends in Design, Manufacturing, Materials and Thermal Sciences (ETDMMT 2020). The contents focus on latest research in product design, CAD/CAE/CFD, robotic systems, neural networks, thermal systems, alternative fuels, propulsion systems, environmental issues related to combustion, autonomous vehicles and alternative energy applications. In addition, the book also covers recent advances in automotive engineering and aerospace technologies. Given the range of contents covered, this book can be useful for students, researchers as well as practicing engineers.
Book Synopsis Wildlife/motor Vehicle Collisions by :
Download or read book Wildlife/motor Vehicle Collisions written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
