Download or read book Response of Propellant Combustion to Unsteady Turbulent Flows written by and published by . This book was released on 1991 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbularization of an acoustic boundary-layer (Stokes layer) on impermeable and permeable surfaces is analytically considered. The theoretical approach utilizes a second-order closure model of turbulence. For simple acoustic boundary-layers on impermeable surfaces, both the approximate solution and the numerical results for the critical acoustic Mach number required for turbulent transition are qualitatively confirmed by experiment. The calculations for acoustic boundary-layers with transpiration (injection) indicate a substantial reduction of the acoustic Mach number required for transition for small values of the normalized injection velocity. The results may provide a mechanism for flow-related combustion instability in practical systems, particularly solid propellant rockets, since turbularization of the near-surface combustion zone could result at relatively low acoustic Mach numbers. An analysis of the transitional and turbulent reactive acoustic boundary layer on a homogeneous solid-propellant surface is conducted to investigate potential mechanisms of combustion instability. A new technique is developed for the condensed-phase thermal layer, in which the propellant space is mapped onto the gas space and efficiently solved using the same adaptive numerical grid. Results are obtained at an acoustic pressure node in the absence of a mean axial flow. The results indicate that acoustically induced transition can occur at relatively low acoustic pressure amplitudes, propellant response to harmonic axial velocity fluctuations is rectified and results in a mean augmentation and that nominal propellant combustion parameters lead to increasing susceptibility to acoustic transition at elevated mean pressures.
Download or read book Response of Propellant Flames to Unsteady Flows and Related Questions written by John Buckmaster and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nonsteady Burning and Combustion Stability of Solid Propellants written by Martin Summerfield and published by AIAA. This book was released on 1992 with total page 922 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Response of Solid Propellant Combustion to the Presence of a Turbulent Acoustic Boundary Layer written by Ted Anthony Roberts and published by . This book was released on 1988 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development of a Computerized Analysis for Solid Propellant Combustion Instability with Turbulence written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-02 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: A multi-dimensional numerical model has been developed for the unsteady state oscillatory combustion of solid propellants subject to acoustic pressure disturbances. Including the gas phase unsteady effects, the assumption of uniform pressure across the flame zone, which has been conventionally used, is relaxed so that a higher frequency response in the long flame of a double-base propellant can be calculated. The formulation is based on a premixed, laminar flame with a one-step overall chemical reaction and the Arrhenius law of decomposition with no condensed phase reaction. In a given geometry, the Galerkin finite element solution shows the strong resonance and damping effect at the lower frequencies, similar to the result of Denison and Baum. Extended studies deal with the higher frequency region where the pressure varies in the flame thickness. The nonlinear system behavior is investigated by carrying out the second order expansion in wave amplitude when the acoustic pressure oscillations are finite in amplitude. Offset in the burning rate shows a negative sign in the whole frequency region considered, and it verifies the experimental results of Price. Finally, the velocity coupling in the two-dimensional model is discussed. Chung, T. J. and Park, O. Y. Unspecified Center NAG8-627...
Download or read book Turbulent Combustion written by Norbert Peters and published by Cambridge University Press. This book was released on 2000-08-15 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: The combustion of fossil fuels remains a key technology for the foreseeable future. It is therefore important that we understand the mechanisms of combustion and, in particular, the role of turbulence within this process. Combustion always takes place within a turbulent flow field for two reasons: turbulence increases the mixing process and enhances combustion, but at the same time combustion releases heat which generates flow instability through buoyancy, thus enhancing the transition to turbulence. The four chapters of this book present a thorough introduction to the field of turbulent combustion. After an overview of modeling approaches, the three remaining chapters consider the three distinct cases of premixed, non-premixed, and partially premixed combustion, respectively. This book will be of value to researchers and students of engineering and applied mathematics by demonstrating the current theories of turbulent combustion within a unified presentation of the field.
Download or read book Solid propellant ignition and unsteady combustion processes written by Leonard H. Caveny and published by . This book was released on 1976 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research carried out under the grant was aimed at furthering the scientific understanding of nonsteady propellant combustion behavior in rocket motor chambers. Controlled nonsteady flow and burning conditions were produced in laboratory-scale solid rocket motors by developing a device that modulated the throat area of the primary nozzle. Modulation frequencies up to 2400 Hz were obtained. The modulated throat rocket motor is being used to acquire data using AP composite propellant grains. Cold flow tests were used to study the acoustic modes and nozzle discharge characteristics. Computerized techniques were developed for conducting spectral analyses of head-end and nozzle-end pressure data. In addition, the equations describing the nonsteady one-dimensional gas dynamics and propellant combustion were formulated, and a comprehensive numerical solution was developed. The present solution takes into account the couplings among the oscillating nozzle flow, the nonsteady chamber flow, and erosive burning. Since pressure and velocity oscillations can be made to occur and decay in high loading density rocket motors with realistic grain configurations, the experiment is expected to produce propellant/chamber response functions that are relatively easy to interpret, compared to the difficult to interpret T-burner response functions.
Download or read book Unsteady Combustion written by F. Culick and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book The Summary of Engineering Research written by University of Illinois at Urbana-Champaign. Office of Engineering Publications and published by . This book was released on 1992 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unsteady Processes in Solid Propellant Combustion written by A. Crespo and published by . This book was released on 1977 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this work is to develop a theoretical analysis of unsteady processes in solid propellant combustion, particularly combustion stability and extinction by rapid depressurization. It is assumed that the solid decomposes at its surface by a pyrolysis law, and the gaseous decomposition products react exothermically following an Arrenius law. The nondimensional activation energy of the gas phase reaction is considered to be large so that the reaction takes place in a thin zone where the temperature is close to the flame temperature. The gas phase is assumed to be quasisteady and under this condition the equations in the gas phase are solved in the limit of high activation energies. The analysis of the energy equation in the condensed phase shows that the characteristic response time of the solid to gas phase perturbations is large compared to the characteristic residence time in the heat-up zone of the solid, their ratio being of the order the nondimensional activation energy in the gas phase reaction. A stability criterion has been obtained, resulting that for large values of the nondimensional activation energy of the pyrolysis law there is always unstable behaviour. For the stable case the dynamic extinction problem is being presently investigated. (Author).
Download or read book Solid Propellant Chemistry Combustion and Motor Interior Ballistics 1999 written by Vigor Yang and published by AIAA. This book was released on 2000 with total page 1038 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Research on Unsteady Combustion Processes written by Leonard H. Caveny and published by . This book was released on 1978 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nonsteady propellant combustion and chamber flow behavior, particularly as they relate to combustion stability and aluminized propellant combustion are being studied. The first part of the study is centered around the modulated throat rocket motor which is being developed to investigate the dynamic responses of high performance rocket motors in which externally excited longitudinal pressure and velocity waves produce coupling with propellant combustion processes. Transfer functions between the measured head-end and nozzle-end pressures produce gain and phase information in the vicinity of the first 3 harmonics.
Download or read book Unsteady Combustor Physics written by Tim C. Lieuwen and published by Cambridge University Press. This book was released on 2021-10-21 with total page 533 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explore a unified treatment of the dynamics of combustor systems, including acoustics, fluid mechanics, and combustion in a single rigorous text. This updated new edition features an expansion of data and experimental material, updates the coverage of flow stability, and enhanced treatment of flame dynamics. Addresses system dynamics of clean energy and propulsion systems used in low emissions systems. Synthesizing the fields of fluid mechanics and combustion into a coherent understanding of the intrinsically unsteady processes in combustors. This is a perfect reference for engineers and researchers in fluid mechanics, combustion, and clean energy.
Download or read book Liquid Propellant Rocket Combustion Instability written by and published by . This book was released on 1972 with total page 668 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book AIAA Journal written by American Institute of Aeronautics and Astronautics and published by . This book was released on 2004 with total page 954 pages. Available in PDF, EPUB and Kindle. Book excerpt:
