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Author: Eric James Jacob
Publisher:
ISBN:
Category :
Languages : en
Pages : 162
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Book Description
Combustion instability (CI) has been persistent in all forms of propulsion since their inception. CI is characterized by pressure oscillations within the propulsion system. If even a small fraction of the dense energy within the system is converted to acoustic oscillations the system vibrations can be devastating. The coupling of combustion and uid dynamic phenomena in a nonlinear system poses CI as a signicant engineering challenge. Drawing from previous analysis, second order acoustic energy models are taken to third order. Second order analysis predicts exponential growth. The addition of the third order terms capture the nonlinear acoustic phenomena (such as wave steepening) observed in experiments. The analytical framework is derived such that the energy sources and sinks are properly accounted for. The resulting third order solution is compared against a newly performed simplied acoustic closed tube experiment. This experiment provides the interesting result that in a forced system, as the 2nd harmonic is driven, no energy is transferred back into the 1st mode. The subsequent steepened waveform is a summation of 2nd mode harmonics (2, 4, 6, 8 ...) where all odd modes are nonexistent. The current third order acoustic model recreates the physics as seen in the experiment. Numerical experiments show the sensitivity of the pressure wave limit cycle amplitude to the second order growth rate, highlighting the importance of correctly calculating the growth rates. The sensitivity of the solution to the third order parameter is shown as well. Exponential growth is found if the third order parameter is removed, and increased nonlinear behavior is found if it retained and as it is increased. The solutions sensitivity to this term highlights its importance and shows the need for continued analysis via increasing the models generality by including neglected eects. In addition, the aect of a time varying second order growth rate is shown. This eect shows the importance of modeling the system in time because of the time lag between changes in the growth rate to a change in the limit cycle amplitude.
Author: Eric James Jacob
Publisher:
ISBN:
Category :
Languages : en
Pages : 162
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Book Description
Combustion instability (CI) has been persistent in all forms of propulsion since their inception. CI is characterized by pressure oscillations within the propulsion system. If even a small fraction of the dense energy within the system is converted to acoustic oscillations the system vibrations can be devastating. The coupling of combustion and uid dynamic phenomena in a nonlinear system poses CI as a signicant engineering challenge. Drawing from previous analysis, second order acoustic energy models are taken to third order. Second order analysis predicts exponential growth. The addition of the third order terms capture the nonlinear acoustic phenomena (such as wave steepening) observed in experiments. The analytical framework is derived such that the energy sources and sinks are properly accounted for. The resulting third order solution is compared against a newly performed simplied acoustic closed tube experiment. This experiment provides the interesting result that in a forced system, as the 2nd harmonic is driven, no energy is transferred back into the 1st mode. The subsequent steepened waveform is a summation of 2nd mode harmonics (2, 4, 6, 8 ...) where all odd modes are nonexistent. The current third order acoustic model recreates the physics as seen in the experiment. Numerical experiments show the sensitivity of the pressure wave limit cycle amplitude to the second order growth rate, highlighting the importance of correctly calculating the growth rates. The sensitivity of the solution to the third order parameter is shown as well. Exponential growth is found if the third order parameter is removed, and increased nonlinear behavior is found if it retained and as it is increased. The solutions sensitivity to this term highlights its importance and shows the need for continued analysis via increasing the models generality by including neglected eects. In addition, the aect of a time varying second order growth rate is shown. This eect shows the importance of modeling the system in time because of the time lag between changes in the growth rate to a change in the limit cycle amplitude.
Author: Joseph D. Baum
Publisher:
ISBN:
Category :
Languages : en
Pages : 45
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Book Description
An existing nonlinear instability model has been extended and improved to allow it to more realistically treat the longitudinal shock wave type of combustion instability frequently encountered in tactical solid rocket motors. Results obtained utilizing this model to investigate limiting amplitude and velocity coupling phenomena in solid rocket motors are presented. An advanced finite difference integration technique capable of accurately describing shocks and contact discontinuities has been incorporated into the computer program, as well as an improved heat conduction solution, an heuristic velocity coupling model, and a spectral analysis capability. Solutions of wave propagation and shock formation and propagation in a variable area duct and a solid propellant rocket motor are presented; as are a number of solutions demonstrating that limiting amplitude is independent of the characteristics of the initial disturbance. Results of a preliminary study of nonlinear velocity modulated limit cycles are presented, as are results that demonstrate the primarily traveling wave nature of nonlinear wave propagation in solid rocket motors, and the complexity of the phase relationships between pressure, burning rate, and velocity oscillations are presented. Finally, the effect of a threshold velocity on non-linear velocity coupled instability was explored, and some of the results are also presented. (Author).
Author: Ben T. Zinn
Publisher:
ISBN:
Category : Combustion
Languages : en
Pages :
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Book Description
Author: Manuel Edward Lores
Publisher:
ISBN:
Category : Rocket engines
Languages : en
Pages : 396
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Book Description
Author: W. A. Sirignano
Publisher:
ISBN:
Category : Rocket engines
Languages : en
Pages : 255
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Book Description
Author: Richard J. Priem
Publisher:
ISBN:
Category : Rockets (Aeronautics)
Languages : en
Pages : 48
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Book Description
Author: Victor Scott Burnley
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 342
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Book Description
Author: Vigor Young
Publisher: AIAA
ISBN: 9781600864186
Category : Liquid propellant rockets
Languages : en
Pages : 606
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Book Description
Annotation Since the invention of the V-2 rocket during World War II, combustion instabilities have been recognized as one of the most difficult problems in the development of liquid propellant rocket engines. This book is the first published in the United States on the subject since NASA's Liquid Rocket Combustion Instability (NASA SP-194) in 1972. In this book, experts cover four major subject areas: engine phenomenology and case studies, fundamental mechanisms of combustion instability, combustion instability analysis, and engine and component testing. Especially noteworthy is the inclusion of technical information from Russia and China--a first.
Author: F. Culick
Publisher: Springer Science & Business Media
ISBN: 9400916205
Category : Technology & Engineering
Languages : en
Pages : 560
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Book Description
This book contains selected papers prepared for the NATO Advanced Study Institute on "Unsteady Combustion", which was held in Praia da Granja, Portugal, 6-17 September 1993. Approximately 100 delegates from 14 countries attended. The Institute was the most recent in a series beginning with "Instrumentation for Combustion and Flow in Engines", held in Vimeiro, Portugal 1987 and followed by "Combusting Flow Diagnostics" conducted in Montechoro, Portugal in 1990. Together, these three Institutes have covered a wide range of experimental and theoretical topics arising in the research and development of combustion systems with particular emphasis on gas-turbine combustors and internal combustion engines. The emphasis has evolved roughly from instrumentation and experimental techniques to the mixture of experiment, theory and computational work covered in the present volume. As the title of this book implies, the chief aim of this Institute was to provide a broad sampling of problems arising with time-dependent behaviour in combustors. In fact, of course, that intention encompasses practically all possibilities, for "steady" combustion hardly exists if one looks sufficiently closely at the processes in a combustion chamber. The point really is that, apart from the excellent paper by Bahr (Chapter 10) discussing the technology of combustors for aircraft gas turbines, little attention is directed to matters of steady performance. The volume is divided into three parts devoted to the subjects of combustion-induced oscillations; combustion in internal combustion engines; and experimental techniques and modelling.
Author: M. R. Beltran
Publisher:
ISBN:
Category : Hydrazines
Languages : en
Pages : 0
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Book Description
Progress made on a study of liquid rocket engine combustion instability is presented. Particular emphasis was placed on the monomethylhydrazine-nitrogen tetroxide system. A steady-state combustion model (vaporization rate controlled) and a nonlinear combustion instability model were developed.
