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Atomization In Gas Centered Swirl Coaxial Injectors Preprint
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Book Synopsis Atomization in Gas-Centered Swirl-Coaxial Injectors (PREPRINT). by :
Download or read book Atomization in Gas-Centered Swirl-Coaxial Injectors (PREPRINT). written by and published by . This book was released on 2006 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: A preliminary study of atomization mechanisms in gas-centered swirl-coaxial injectors for use in rocket engines has been undertaken. Gas-centered swirl-coaxial injectors differ from other injectors in that atomization occurs from a wall-bounded liquid. Few studies of atomization mechanisms in wall-bounded flows exist; some probable atomization processes have been determined, however. These mechanisms include liquid turbulence, aerodynamic stripping and a process driven by gas-phase structures. The likely character of the gas and film undergoing these atomization processes is presented. Relevant nondimensional groupings based on simplified theoretical descriptions of select mechanisms are outlined. Preliminary experimental and numerical results taken at atmospheric pressure are qualitatively compared to the likely mechanisms and each other.
Book Synopsis Atomization Rate of Gas-Centered Swirl-Coaxial Injectors (Preprint). by :
Download or read book Atomization Rate of Gas-Centered Swirl-Coaxial Injectors (Preprint). written by and published by . This book was released on 2008 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gas-centered swirl-coaxial injectors are garnering much interest in the area of liquid hydrocarbon rocket development. However, robust design criteria and scaling of these injectors remains unclear. Here an examination of primary atomization has been undertaken through the study of a gas-centered swirl-coaxial injector. Film length is measured experimentally over a range of operating conditions and injector geometries. Experiments are performed at atmospheric pressure using water and nitrogen as working fluids. The atomization rate, reflected in the length of the intact liquid film, is related to the momentum flux ratio. Using the characteristic dimensions for determining the bulk velocities of the fluids, the film lengths of various injector geometries may be collapsed onto a single curve of nondimensionalized length versus momentum flux ratio. The injectors tested have a geometry which produces separated gas flow just prior to contact with the liquid. The effect of this recirculation zone on initial film height is discussed.
Book Synopsis Atomization Performance Predictions of Gas-Centered Swirl-Coaxial Injectors by :
Download or read book Atomization Performance Predictions of Gas-Centered Swirl-Coaxial Injectors written by and published by . This book was released on 2007 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ability to predict injector performance can reduce the cost of rocket engine development. This paper details a new theory to predict the atomization efficiency and droplet diameter from the atomization of wall-bounded films with strong gas-phase influences. In this theory atomization occurs when a disturbance is created on the film surface then breaks down into droplets via stripping. The theory relates the mass of film lost via atomization to the mass of liquid introduced into the atomizer to predict atomization efficiency and offers some estimations of primary droplet diameter. A specific example involving a gas-centered swirl coaxial injector is discussed. The results of experiments and simulations are used to support assumptions and are successfully compared to some simple predictions from the theory. Despite the application to a specific injector efforts are made to keep the theory as general as possible so that it applies to many types of injectors and a wide range of operating conditions.
Book Synopsis A Method to Predict Atomization Performance in Gas-Centered Swirl-Coaxial Injectors by :
Download or read book A Method to Predict Atomization Performance in Gas-Centered Swirl-Coaxial Injectors written by and published by . This book was released on 2007 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ability to predict atomizer performance can reduce the cost of system development in many areas. This paper investigates the atomization efficiency and droplet distribution from films with strong gas-phase influences. A prediction of atomization efficiency based on a general theory of the droplet creation process is given. In this process a disturbance is created on the film surface then broken down into droplets via stripping. The theory relates the mass of film lost via atomization to the mass of liquid introduced into the atomizer to predict atomization efficiency and offers some estimations of primary droplet diameter. A specific example involving a gas-centered swirl coaxial injector is given to illustrate how the theory would be applied; however, efforts are made to keep the model as general as possible so that it applies to many types of atomizers and a wide range of operating conditions.
Book Synopsis Swirl Coaxial Injector Development, Part I: Test Results by :
Download or read book Swirl Coaxial Injector Development, Part I: Test Results written by and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sierra Engineering, in conjunction with the Air Force Research Laboratory Propulsion Directorate, has undertaken a program to develop a gas-centered, swirl coaxial injector. This injector design will be used in the multi-element Advanced Fuels Tester (AFT) engine to test a variety of hydrocarbon propellants. As part of this program, a design methodology is being developed which will be applicable to future injector design efforts. The methodology combines cold flow data, acquired in the AFRL High Pressure Injector Flow facility, uni-element hot fire data, collected in AFRL Test Cell EC-1, and a computational effort conducted at University of Alabama-Birmingham, to identify key design features and sensitivities. Results from the computational effort will be presented in the Part II companion paper (9). Three different gas-centered swirl coaxial element concepts were studied: a converging design, a diverging design, and a pre-filming design. The cold flow experiments demonstrated that all three classes of elements produced an extremely dense, solid cone spray, with the highest mass density in the center. The atomization of all of these injectors was excellent, producing mean drop sizes 1/3 to 1/4 of that typically measured for shear coaxial elements operating under similar conditions. Uni-element hot fire testing of these elements has begun, but the elements have not yet been tested at the design operating conditions. Preliminary low chamber pressure test results show the converging design performs better than the pre-filming and diverging design. Uni-element C ̂efficiencies in excess of 90% have been measured over a wide-range of mixture ratios.
Book Synopsis Modeling of the Internal Two-Phase Flow in a Gas-Centered Swirl Coaxial Fuel Injector by :
Download or read book Modeling of the Internal Two-Phase Flow in a Gas-Centered Swirl Coaxial Fuel Injector written by and published by . This book was released on 2009 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Predicting the liquid film dynamics inside the injector cup of gas-centered swirl coaxial fuel injectors requires a general two-phase approach that is appropriate for all liquid volume fractions, high Weber number, and complex geometries. The rapid exchange of momentum at the highly convoluted interface requires tight numerical coupling between the gas and liquid phases. An Eulerian two-phase model is implemented to represent the liquid and gas interactions in the injector as well as the atomization processes at the rough interface. The model, originally proposed by Vallet et al, assumes that in the limit of infinite Reynolds and Weber number, features of the atomization process acting at large length scales are separable from small scale mechanisms. A transport equation for the liquid volume fraction represents the dispersion of the liquid into the gas via a traditional turbulent diffusion hypothesis. A model for the growth of mean interfacial surface area is then used to characterize the growth of instability at the interface, allowing a characterization of Sauter mean diameter. The model shows promise as a computationally inexpensive tool for characterizing spray quality in regions where optical experimental data are difficult to obtain and two-phase direct numerical simulation methods are too demanding.
Book Synopsis Swirl Effects on Coaxial Injector Atomization by :
Download or read book Swirl Effects on Coaxial Injector Atomization written by and published by . This book was released on 1996 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: The focus of this AASERT grant was the investigation of atomization processes for swirl coaxial gas/liquid spray injection for rocket combustor applications. The work has included review and analysis of atomization literature for swirled and non-swirled gas/liquid sprays, design and fabrication of a rocket-scale swirl coaxial injector for research, and cold-flow and hot-fire characterizations of atomization and combustion with the designed injector. Two significant findings have emerged from the present studies; (1) our experiments in a windowed research combustor were the first to demonstrate that swirl coaxial injection allows for highly efficient propellant combustion (liquid oxygen/gaseous hydrogen) over a wide range of oxidizer-to-fuel ratios from 3 to 175. The result was of interest to industry in conceptual design of a novel rocket-engine cycle, for RLV application, relying upon very high oxidizer-to-fuel ratio combustion in a liquid oxygen preburner, and (2) optical diagnostics were applied to demonstrate a methodology for scaling spray drop size/velocity results based on liquid Weber number. This is of intrinsic value to the spray community, and of direct impact within the rocket-injector design community, where the scaling approach can be incorporated into injector sizing activities.
Book Synopsis Swirl Coaxial Injector Development by :
Download or read book Swirl Coaxial Injector Development written by and published by . This book was released on 2002 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sierra Engineering and the Air Force Research Laboratory Propulsion Directorate, have undertaken a program to develop gas-centered, swirl coaxial injectors. This injector design will be used in the multi-element Advanced Fuels Tester (AFT) engine to test a variety of hydrocarbon propellants. As part of this program, a design methodology is being developed which will be applicable to future injector design efforts. The methodology combines cold flow data, acquired in the AFRL High Pressure Injector Flow facility, uni-element hot fire data, collected in AFRL Test Cell EC-1, and a computational effort conducted at University of Alabama-Birmingham, to identify key design features and sensitivities. Only results from the experimental effort will be presented in this work. Three different gas-centered swirl coaxial element concepts are being studied: a converging design, a diverging design, and a pre-filming design. The cold flow experiments demonstrated that all three classes of elements produced an extremely dense, solid cone spray, with the highest mass density in the center. The atomization of all of these injectors was excellent, producing mean drop sizes 1/3 to 1/4 of that typically measured for shear coaxial elements operating under similar conditions. Uni-element hot fire testing has found that the converging designs produce C* efficiencies in excess of 90% over a wide-range of mixture ratios and pressure conditions. Near the design pressure, efficiencies exceeding 96% have been measured. In the diverging designs, a chamber oscillation of near 200 Hz has been noted. The cause of this oscillation is under investigation.
Book Synopsis Effect of Cup Length on Film Profiles in Gas-Centered Swirl-Coaxial Injectors by :
Download or read book Effect of Cup Length on Film Profiles in Gas-Centered Swirl-Coaxial Injectors written by and published by . This book was released on 2009 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent interest in LOX-hydrocarbon rocket engines has resulted in the need for design criteria and scaling laws for injectors which work well in such an environment. One injector type that has been shown to work well in LOX-hydrocarbon engines is a Gas-Centered Swirl-Coaxial (GCSC) Injector. While earlier work has focused on a number of the important parameters, one that has been left unexplored is the injector cup length. In this study the effect of the injector cup length on the atomizing film in GCSC injectors is explored. The length of the atomizing film is used as reference parameter for the overall spray quality. Using laser-sheet illuminations along with water and nitrogen as the working fluid, film lengths and were determined in six unique injector geometries and over a number of flow conditions. Each injector geometry and flow condition was tested with two injector cup lengths. Results will show that the injector cup length has little effect on the films for test conditions with momentum-flux ratios greater than 400 as long as the film is completely broken up within the cup.
Book Synopsis Numerical Analysis on Combustion Characterization of Gas Centered Swirl Coaxial Injector by : 許庫瑪
Download or read book Numerical Analysis on Combustion Characterization of Gas Centered Swirl Coaxial Injector written by 許庫瑪 and published by . This book was released on 2018 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Investigation on Dynamic Spray Characteristics of Gas-centered Swirl Coaxial Injector by : York Tzuyu Lin
Download or read book The Investigation on Dynamic Spray Characteristics of Gas-centered Swirl Coaxial Injector written by York Tzuyu Lin and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to the popularity in space exploration, the importance of liquid propellant rocket engines (LPRE) has increased. Gas-centered swirl coaxial (GCSC) injectors are widely implemented in gas-generation cycled LPREs. Thus, GCSC injectors has been a popular subject these years. The aims of this thesis were to establish a design process of LPRE and GCSC injector, and gain deeper understanding of the behavior of GCSC injector under large amplitude flowrate variation by conducting dynamic cold flow experiment using self-developed flowrate excitation ball valve. The LPRE and GCSC injector were firstly designed by theoretical formulae, and the detailed design were done with key geometric parameters acquired for future ground static test and cold flow experiments. After that, full-bridge gate driver and microcontroller chips were used to developed a DC motor controller. Angular position controller was realized by LabView, incremental encoder, DC motor and DC motor controller mentioned above. Finally, both steady and dynamic cold flow experiments were conducted with self-constructed backlight illumination observation system, fluid supply system, flowrate excitation ball valve, and GCSC injectors. After analyzing the results of cold flow experiment with self-developed computer program, four major conclusions were made: 1. The design of changing gas nozzle length to change recess ratio was found to be weakening the swirl strength. 2. The pressure oscillation in liquid manifold would create addition perturbation to liquid film, leading to the shortening of breakup length. 3. Large intact liquid films were more sensitive to change in gas momentum. 4. Momentum ratio was found to be a dominant factor determining the general breakup of liquid film based on the fact that spray cone structure was independent of phase difference in pressure oscillation.
Book Synopsis Atomization and Mixing Characteristics of Gas/liquid Coaxial Injector Elements by : R. J. Burick
Download or read book Atomization and Mixing Characteristics of Gas/liquid Coaxial Injector Elements written by R. J. Burick and published by . This book was released on 1971 with total page 7 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.
Book Synopsis Atomization and Sprays by : Arthur Lefebvre
Download or read book Atomization and Sprays written by Arthur Lefebvre and published by CRC Press. This book was released on 1988-12-01 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atomization and Sprays examines the atomization of liquids and characteristics of sprays. It explains the physical processes of atomization as well as guidelines for designing atomizers. In addition, it demonstrates how the importance of the size and velocity of a particle contributes to improved spray characterization. Coverage includes general co
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
Book Synopsis Swirl Coaxial Injector Development, Part II: CFD Modeling by :
Download or read book Swirl Coaxial Injector Development, Part II: CFD Modeling written by and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Injector design is critical to obtaining the dual goals of long engine life as well as providing high energy release efficiency in the main combustion chamber. Introducing a swirl component in the injector flow can enhance the propellant mixing and thus improve engine performance. A combined experimental and computational effort is underway to examine the properties of GOX-centered, swirl coaxial injectors to examine their performance and lifetime characteristics. These injectors can be easily manufactured and can be designed to maintain a low face temperature, which will improve engine life. Therefore, swirl coaxial injectors, which swirl liquid fuel around a gaseous oxygen core, show promise for the next generation of high performance staged combustion rocket engines utilizing hydrocarbon fuels. The purpose of this work is to not only examine the properties of these injectors, but also to develop a design methodology, utilizing a combination of high-pressure cold-flow testing, uni-element hot- fire testing, and computations to create a high performing, long life swirl coaxial injector for multi-element combustor use.
Book Synopsis Atomization Mechanism of Wall-Bounded Two-Phase Flows by :
Download or read book Atomization Mechanism of Wall-Bounded Two-Phase Flows written by and published by . This book was released on 2005 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: The current understanding of droplet generation processes from liquid films is reviewed. Films are defined as liquids with one free and one wall-bound surface. In many of the systems where films occur, atomization is an undesirable side-effect of the two-phase flow. The motivation for this study, however, is a process where atomization from the film is the goal -- a gas-centered swirl coaxial rocket injector. Because atomization is often unwanted in film configurations, few studies focus on the mechanisms that cause atomization. The large body of literature on the atomization of jets and sheets is, therefore, utilized to develop an understanding of film atomization. Similarities and differences between the geometries are discussed as applicable. Generally, the atomization is considered to involve two steps: the creation of a disturbance on the film surface and the breakdown of this disturbance into droplets. Prompt atomization, where atomization occurs directly at a nozzle exit, is also briefly considered. Several atomization mechanisms are identified and qualitatively described.
