Download or read book CFD Modelling of Solid Propellant Ignition written by C. Lowe and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book CFD Modelling of Solid Propellant Ignition written by and published by . This book was released on 1907 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Solid propellant is the highly energetic fuel burnt in the combustion chamber of ballistic weapons. It is manufactured, for this purpose, in either granular or stick form. Internal ballistics describes the behavior within the combustion chamber throughout the ballistic cycle upto projectile exit from the muzzle of the gun barrel. Over the last twenty years this has been achieved by modelling the process using two-phase flow equations. The solid granules or sticks constitute the first phase, which can be assumed to be incompressible over typical pressure ranges within the chamber. The gas-phase is composed of both the original ambient gas contained around the propellant and additional gas produced by the propellant gasifying on heating. Equations can be derived that describe the conservation of mass, momentum and energy in terms of average flow variables. The equations are a highly non-linear system of partial-differential- equations. High-speed flow features are observed in internal ballistics and ordinary fini te- difference methods are unsuitable numerical methods due to inaccurate prediction of discontinuous flow features. Modern shock-capturing methods are employed, which solve the system of equations in conservation form, with the ability to capture shocks and contact discontinuities. However, although the numerical solutions compare well with experiment over the bulk of the combustion chamber, the ignition models used in internal ballistics are unreliable. These are based on either gas or solid-surface temperature achieving some empirically measured 'ignition temperature' after which the propellant burns according to an empirical pressure dependent burning law. Observations indicate that this is not an adequate representation of ignition. Time differences between first solid gasification and ignition imply two distinct processes occurring.]Further, ignition occurring in gas-only regions indicates that ignition is controlled by a gas-phase reaction. This thesi.
Download or read book Modeling Solid Propellant Ignition Events written by Daniel Austin Smyth and published by . This book was released on 2011 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation documents the building of computational propellant/ingredient models toward predicting AP/HTPB/Al cookoff events. Two computer codes were used to complete this work; a steady-state code and a transient ignition code.
Download or read book U S Army Workshop on Solid Propellant Ignition and Combustion Modeling written by Martin S. Miller and published by . This book was released on 1997-07 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: A workshop with the objective to view the current state of the art of energetic-material combustion models within the context of future requirements of gun interior-ballistics (IB) models was held at the U.S. Army Research Laboratory (ARL), Aberdeen Proving Ground, MD, on 9 and 10 April 96. The workshop was motivated by the recognition that modeling and simulation will be an essential cost-saving and time-saving tool in the design, development, testing, and evaluation of future gun-propulsion systems, and that, under current funding constraints, research on the underlying fundamentals must be carefully directed toward the most critical technology barriers. To facilitate this process, a perspective was presented on the fundamental physics and chemistry currently utilized in IB codes (XKTC, etc.) and the extensions planned for advanced codes (the NGEN family). The state of the art in fundamental descriptions of energetic-material combustion was then summarized and discussed with the intent of giving focus to those issues that could impact the future development needs of the IB research community.
Download or read book Solid Propellant Underwater Ignition Modeling written by A. B. Vorozhtsov 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 A Model of the Ignition of a Heterogeneous Solid Rocket Propellant written by Larry Sidney Bouck and published by . This book was released on 1966 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ignition transient Modeling for Solid Propellant Rocket Motors written by P. V. S. Alavilli and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book CFD Analysis of Solid Rocket Motors written by Krishna Pandey and published by LAP Lambert Academic Publishing. This book was released on 2015-03-17 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: Determination of the grain geometry is an important and critical step in the design of solid propellant rocket motors. Because, the performance of the rocket is greatly effect by the burning surface area of the solid propellant. The performance prediction of the solid rocket motor can be achieved easily if the burn back steps of the grain are known. In this study, grain burn back analysis for 3-D star grain geometries was investigated. The method used was solid modeling (ANSYS(r) - DM, PRO-E and GAMBIT) of the propellant grain for predefined intervals of burn back. In this method, the initial grain geometry was modeled parametrically using ANSYS software. For every burn step, the parameters were adapted and the new grain geometry was modeled, for analysis three cases of grain geometries was considered during the combustion. By analyzing these geometries, burn area change of the grain geometry was obtained. Using this data and internal ballistic parameters, the performance of the solid propellant rocket motor in terms of motor pressure was achieved.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Unified Theory of Solid Propellant Ignition Part 1 Development of Mathematical Model written by H. H Bradley (Jr) and published by . This book was released on 1974 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: The governing equations of solid propellant ignition in one space dimension are derived from conservation and transport considerations. The resulting mathematical model contains as subcases the existing gas phase, solid phase, and surface ignition theories. More important, it allows the effect of the site of chemical reaction on the ignition transient to be examined with consistent and compatible boundary conditions. Surface regression and the first order effect of nonunity Lewis number are retained to allow examination of the effect of these phenomena which are often neglected. Several second order terms are dropped from the more general equations in the interest of mathematical tractability; these include variable specific heat and transport coefficients. Finally, the physical equations are transformed for computer coding. (Modified author abstract).
Download or read book CFD Modeling of Ignition and Soot Formation for Advanced Compression ignition Engines written by Jun Han and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Piston-engine-powered ground vehicles account for a large fraction of the U.S. consumption of petroleum-based fuels, and are major sources of pollutant emissions including oxides of nitrogen, particulate matter, and greenhouse gases. With uncertainties in crude oil supplies and increasingly stringent emissions regulations, advanced-concept engines and alternative (non-petroleum-derived) fuels have become active research areas. Of particular interest are low-temperature combustion strategies for compression-ignition engines that have the potential for high efficiency with low in-cylinder emissions formation. To make progress, predictive computational fluid dynamics (CFD) tools are needed that can provide insight into in-cylinder processes in hostile aero-thermo-chemical environments with unconventional fuels. Challenges include: dealing with multiphase turbulent flow in complex geometric configurations with moving boundaries; accounting for unresolved turbulent fluctuations in velocity, composition, and temperature; and availability of gas-phase reaction mechanisms and soot models that capture autoignition, combustion, and emissions formation under relatively unexplored conditions. This thesis focuses on two topics related to CFD modeling for advanced compression-ignition engines: the ignition behavior of gasoline-like fuels under homogeneous low-temperature-combustion conditions, and the ignition and sooting characteristics of a class of molecules that is representative of those in algae-derived fuels under conditions that are representative of a direct-injection diesel engine. In both cases, an unsteady Reynolds-averaged (URANS) modeling approach is used, and model results are compared with available experimental data. For the first part, a CFD model of a Cooperative Fuel Research (CFR) engine was developed and exercised to explore the ignition behavior of low-reactivity (gasoline-like) two- and three-component fuel blends under extremely fuel-lean conditions. The principal metric of interest was the critical compression ratio (CCR), which is defined as the minimum compression ratio for which complete ignition is achieved, as determined by computed or measured CO levels. The ability of several chemical mechanisms from the literature to capture the experimentally measured CCRs over a range of conditions was evaluated. No single mechanism performed best for all fuel blends and all conditions. Furthermore, even in cases where CCRs were computed accurately, significant differences were found between measured and computed apparent-heat-release rates, suggesting that the reaction mechanisms do not accurately represent the kinetics of the ignition process. An initial reaction pathways analysis provided some insight into the reasons for the observed discrepancies between model and experiment. For the second part, a CFD model of a constant-volume high-pressure combustion chamber was exercised to explore the ignition and sooting behavior of two large n-alkane molecules (n-dodecane and n-hexadecane) under diesel-engine-relevant conditions. The extent to which unresolved turbulent fluctuations influence the results was determined by comparing results from a model that accounts for turbulent fluctuations (a transported probability density function-- tPDF-- method) with one that ignores them (a locally well-stirred-reactor-- WSR-- model). The largest influence of turbulent fluctuations was found to be in the soot predictions, which were in better agreement with the experiment for the tPDF model. Differences between n-dodecane and n-hexadecane results were found to be small. There is some evidence from the literature that it may be possible to take advantage of differences between the physical and chemical properties of these two molecules in an engine to realize nonnegligible differences in efficiency and soot levels. However, more sophisticated gas-phase chemistry and soot models may be needed to capture the subtle differences in CFD modeling.
Download or read book Fundamentals of Solid Propellant Combustion written by K. K. Kuo and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Ignition Transient Model for Solid Propellant Rocket Motors written by L. d'Agostino and published by . This book was released on 2001 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 Scientific and Technical Aerospace Reports written by and published by . This book was released on 1989 with total page 1148 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Research on Solid Propellant Ignition Part I Theoretical Search for Analytical Solutions to the Gas Phase Ignition Problem Part Ii Effects of Fuel Volatility and Other Physical and Chemical Factors on Ignitability written by C. H. WALDMAN and published by . This book was released on 1966 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt: The mechanism of ignition being analyzed is based on the hypothesis that the runaway reaction occurs in the gas phase, in a thin boundary layer adjacent to the solid propellant surface being heated, between the reactive fuel and oxident vapors liberated from the surface. Differential equations can be written for the diffusion of vapors from the surface, reaction in the gas phase, heat feedback to the surface, and heating up of the surface. As a first treatment the propellant is taken as a simple fuel and the oxidant is available only in the gas phase. An experimental study was conducted to determine the ignition delay time for various hydrocarbons and for solid propellants when exposed suddenly to a hot, high pressure oxidizing atmosphere. The main purpose was to measure effects that would help in a diagnostic way to decide whether the gas phase theory of ignition is based on the correct physical model. Attempts were made to relate the ignition delay to physical and chemical properties of the fuel to test the hypothesis that the ignition reaction of these compounds starts in the gas phase. A 19 foot long, 1.6 inch I.D. shock tube was used as an investigating tool. The test gas was heated to 1400K behind the reflected shock wave at the end wall of the shock tube. (Author).
Download or read book Solid Propellant Combustion Analysis Using CFD written by A. Demeure and published by . This book was released on 2005 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:
