Download or read book Transient Ignition Mechanisms of Confined Solid Propellants Under Rapid Pressurization written by Kenneth K. Kuo and published by . This book was released on 1980 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive theoretical model was formulated to study the transient ignition mechanisms of solid propellants under rapidly varying pressure conditions. The model considers a two-dimensional geometry to describe the ignition of a heterogeneous propellant. The rate of pressurization has been included in the energy equation to simulate rocket motor ignition conditions. The model does not make any a priori assumption of solid-phase, heterogeneous, or gas-phase ignition mechanism. Chemical reactions are considered in the gas phase, at the interface as well as in the subsurface. The most up-to-date chemical kinetics information is included in the model. A generalized ignition criterion has been proposed which allows ignition to occur at any site.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Download or read book Technical Abstract Bulletin written by and published by . This book was released on 1980 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Transient Combustion in Solid Propellant Cracks written by and published by . This book was released on 1977 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: A one-dimensional theoretical model, incorporating the Noble-Abel dense gas law, has been developed to describe the transient model combustion phenomena inside a propellant crack. The theoretical model can be used to predict wave phenomena, heat transfer from the gas to the propellant surface and associated thermal penetration, flame propagation, and resultant pressurization at various locations along the propellant cavity. Calculations made with the current theoretical model revealed that the internal pressurization rate, pressure gradient, and flame velocity in propellant cracks (for which gases can penetrate) decrease as: the gap width increases, the rocket chamber pressurization rate decreases, and the propellant gasification temperature increases. Additionally, the predicted flame spreading was found to decelerate in a region near the crack tip; this phenomena has been experimentally observed by others.

Download or read book Solid Propellant Ignition and Response of Combustion to Pressure Transients written by Guenther Von Elbe and published by . This book was released on 1966 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ignition of Composite Propellants Under Rapid Pressure Loading written by and published by . This book was released on 1981 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive theeoretical model for ignition of composite solid propellants was proposed as a framework for formulating ignition models for different propellants under a wide range of operating conditions. Detailed chemical kinetics information for the AP/PBAA propellants was incorporated into the proposed theoretical model for ignition of composite solid propellants, enabling a more complete description of source terms in the gas-phase energy and species equations. Solid-phase energy equations were coded and implemented on a computer. Numerical solutions of the solid-phase subprogram were successfully checked against analytic solutions for some limiting cases. Using actual measured heat flux near the propellant surface as an input to the solid-phase equations, predictions for the ignition delay time were made. Effects of pressurization rate, crack-gap width, and igniter-flame temperature on the ignition of AP-based composite solid propellants located at the tip of an inert crack were studied. The ignition process was observed by using a high-speed camera ( -40,000 pictures/s) and a fast-response photodiode system. Heat flux to the propellant surface was measured with a thin film heat-flux gage. A bright luminous zone behind the reflected compression wave was observed at high pressurization rates. The decrease in ignition delay with increasing pressurization is caused by enhanced heat feedback to the propellant surface at higher pressurization rates.

Download or read book Combustion Transients of Solid Propellants written by Norman W. Ryan and published by . This book was released on 1973 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report is largely a restatement of conclusions, with reference to previous publications for details. The areas of study reported are an evaluation of the hot-wire-ignition method for characterizing propellants; the development and study of a gas-fueled analog of the solid-propellant T-burner; a study of low frequency (L*) combustion of L* during a test; a study of high frequency acoustic instability of solid propellants, both a T-burner and a radial-mode, radial-flow burner being used with the same propellants systems; the development and evaluation of a technique for measuring the solid-propellant response function to external energy perturbations at the burning surface; the measurement and evaluation of transient temperatures of propellant flames during rapid depressurization; and a detailed characterization of the low-pressure-combustion phenomena for several different solid propellants including studies of the low-pressure deflagration limit, the electrical conductance near the surface, the extinguishment requirements, and spontaneous reignition. (Author Modified Abstract).

Download or read book Research on Non steady Burning of Solid Propellants with Special Reference to Combustion Instability written by Martin Summerfield and published by . This book was released on 1968 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall objective of the research program has been to study the non-steady burning characteristics of solid rocket propellants, both experimentally and theoretically, to establish a basis for avoiding combustion instability in rocket motors and for predicting thrust transients during motor ignition and extinction. A new non-steady burning model for composite propellants was formulated in which the key element, the non-steady heat feedback law from the gaseous flame, was shown to be a function of the instantaneous pressure and burning rate. Solutions to this model showed that burning stability is largely determined by the exothermicity of reactions in the immediate neighborhood of the propellant surface and by the sensitivity of burning rate to surface temperature. The predictions of the model were generally confirmed by T-motor and rapid pressurization experiments. The non-steady burning model was also used to analyze L-star combustion instability in rocket motors and to demonstrate the feasibility of a novel mechanism for suppression of combustion instability by aluminum addition to a propellant. (Author).

Download or read book Effect of Composition on Combustion of Solid Propellants During a Rapid Pressure Decrease written by Carl C. Ciepluch and published by . This book was released on 1962 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Ignition Transient in Solid Propellant Rocket Motors written by Kim H. Parker and published by . This book was released on 1966 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Normal Acceleration on Transient Burning rate Augmentation of an Aluminized Solid Propellant written by G. Burton Northam and published by . This book was released on 1972 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: Instantaneous burning rate data for a polybutadiene acrylic acid propellant, containing 16 weight percent aluminum, were calculated from the pressure histories of a test motor with 96.77 sq cm of burning area and a 5.08-cm-thick propellant web. Additional acceleration tests were conducted with reduced propellant web thicknesses of 3.81, 2.54, and 1.27 cm. The metallic residue collected from the various web thickness tests was characterized by weight and shape and correlated with the instantaneous burning rate measurements. Rapid depressurization extinction tests were conducted in order that surface pitting characteristics due to localized increased burning rate could be correlated with the residue analysis and the instantaneous burning rate data. The acceleration-induced burning rate augmentation was strongly dependent on propellant distance burned, or burning time, and thus was transient in nature. The results from the extinction tests and the residue analyses indicate that the transient rate augmentation was highly dependent on local enhancement of the combustion zone heat feedback to the surface by the growth of molten residue particles on or just above the burning surface. The size, shape, and number density of molten residue particles, rather than the total residue weight, determined the acceleration-induced burning rate augmentation.

Download or read book Propellant Crack Tip Ignition and Propagation Under Rapid Pressurization written by and published by . This book was released on 1982 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two major tasks performed during the report period were investigation of: (1) crack tip ignition phenomena under rapid pressurization and (2) crack propagation. Ignition of AP-based composite solid propellants located at the tip of an inert crack was investigated both experimentally and theoretically. Results indicate that the ignition-delay time decreases and the heat flux to the propellant surface increases as the pressurization rate is increased. In the theoretical investigation of the tip ignition event a comprehensive model for ignition of AP-based composite solid propellants was developed and numerical solutions were obtained. Crack propagation in a burning composite solid propellant subjected to rapid pressurization in the order of 10 GPa/s was investigated experimentally. The effect of pressurization rate on both crack propagation velocity and time variation of crack shape was studied. Experimental results indicated that the crack velocity increases as the pressurization rate is raised.

Download or read book Mechanics and Chemistry of Solid Propellants written by and published by . This book was released on 1967 with total page 656 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Composite Solid Propellant Ignition Mechanisms written by Larry J. Shannon and published by . This book was released on 1967 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface structures of thermoplastic and elastomeric fuels were found to be markedly different upon exposure to conductive heating from a doubly compressed stagnant gas at oxygen concentrations below those required to cause ignition. The thermoplastic polymers exhibited a molten surface, while the elastomeric fuels showed no visible changes. Vaporization followed by a gas-phase reaction is the probable ignition mechanism for the thermoplastic fuels in the shock tube environment. A gas-solid reaction may occur in the ignition of elastomeric polymers. No general conclusion can be drawn regarding the precise nature of the oxygen-polymer ignition process in the shock tube environment as consideration must be given to the physical structure of the polymer surface. Ignition characteristics of several representative ammonium perchlorate composite propellants were studied using the arc-imaging furnace. The nature of the fuel component was found to have the major influence on the ignition time, and the effect is related to the initial pressure. A model describing composite propellant ignition in a neutral environment was formulated and programmed for computer studies.

Download or read book Initiation Mechanisms of Solid Rocket Propellant Detonation written by Hyla S. Napadensky and published by . This book was released on 1972 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: The mechanisms which may lead to detonation initiation in solid rocket propellants due to accidentally applied low amplitude stimuli are studied. In particular, the effects of low speed impact are studied. A two- dimensional Lagrangian computer code is used to study the detailed hydrodynamic (or elastic-plastic) and thermodynamic behavior of propellant materials under impact conditions. It was found that only moderate temperature increases are generated in unconfined impact of a cylindrical material billet upon a rigid surface. When a second boundary is introduced, i.e., the material is at rest on a rigid base and is impacted by a rigid plate, the temperatures developed under certain conditions exceed the values achieved in unconfined impact by more than a factor of two.

Download or read book Crack Propagation and Branching in Burning Solid Propellants and Ignition of Nitramine Based Composite Propellants written by Kenneth K. Kuo and published by . This book was released on 1986 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three major tasks performed during the report period of investigation were: i) crack propagation and branching in burning solid propellants, ii) ignition of nitramine-based composite propellants under rapid pressurization, and iii) ignition of nitramine-based composite propellants by CO2 laser. Propellant samples have been recovered by interrupted burning experiments. Four modes of crack propagation and/or branching were observed. The amount of surface area generated by mixed or branched modes is substantially higher than that of the single crack propagation mode, and thus could cause sufficiently severe burning in the damaged zone to result in rocket motor failure. The crack propagation problem is analyzed through the use of basic physical principles, experimental results, and Schaper's theory of crack propagation. A set of governing dimensionless parameters which control and characterize the degree of damage has been obtained. These parameters can be used to develop guidelines for safe operating conditions of rocket motors. Ignition characteristics of a series of RDX-based composite propellants were studied. The times for the onset of light emission (t sub LE) of different propellants under rapid pressurization were compared. It is also found that propellant samples with shorter t sub LE do not necessarily show higher mass consumption, this indicates that propellant vulnerabilty should be evaluated by both t sub LE and the fraction of mass consumed.

Download or read book Fast Reactions in Energetic Materials written by Alexander S. Shteinberg and published by Springer. This book was released on 2009-08-29 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modern energetic materials include explosives, blasting powders, pyrotechnic m- tures and rocket propellants [1, 2]. The study of high-temperature decomposition of condensed phases of propellants and their components (liquid, solid and hybrid) is currently of special importance for the development of space-system engineering [3, 4]. To better understand the burning mechanisms (stationary, nonstationary, - steady) of composite solid propellants and their components, information about the macrokinetics of their high-temperature decomposition is required [5]. To be able to evaluate the ignition parameters and conditions of safe handling of heat-affected explosives, one needs to know the kinetic constants of their high-temperature - composition. The development of new composite solid propellants characterized by high performance characteristics (high burning rates, high thermal stability, stability to intrachamber perturbations, and other aspects) is not possible without quanti- tive data on the high-temperature decomposition of composite solid propellants and their components [6]. The same reasons have resulted in signi?cant theoretical and practical interest in the high-temperature decomposition of components of hybrid propellants. It is known that hybrid propellants have not been used very widely due to the low bu- ing (pyrolysis) rates of the polymer blocks in the combustion chambers of hybrid rocket engines. To increase the burning rates it is necessary to obtain information about their relationships to the corresponding kinetic and thermophysical prop- ties of the fuels.