Progress in the Development of a Multiphase Turbulent Model of the Gas/Particle Flow in a Small-Caliber Ammunition Primer PDF Download
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Author: Publisher: ISBN: Category : Languages : en Pages : 44
Book Description
There is significant experimental evidence that burning particles of various chemical compositions and sizes are ejected from gun primers and that these particles interact with the propellant grains during main charge ignition. This explicit ignition phenomenon is thought to be incompatible with the implicit treatment of primer function in conventional interior ballistics codes and models. Generally, the primer efflux is treated as a hot gas that evolves from a specified region in the model's representation of the gun chamber (usually along the chamber centerline and near the breech). What amounts to an igniter table is arrived at by experimental means and by careful calibration of the interior ballistics simulation using gun firing data. With the advent of multidimensional, multiphase interior ballistics codes which employ coupled Eulerian-Lagrangian schemes to explicitly treat both the gas and solid phase, the time is ripe for a primer model that is commensurate with the availability of such an interior ballistics model. Progress in the development of a primer model that is compatible with the ARL-NGEN3 interior ballistics code and small-caliber weapons is described herein. The model is based on the One Dimensional Turbulence modeling approach that has recently emerged as a powerful tool in multiphase simulations. Initial results are shown for the model run as a stand-alone code and are compared to recent experiments with small-caliber primers.
Author: Publisher: ISBN: Category : Languages : en Pages : 44
Book Description
There is significant experimental evidence that burning particles of various chemical compositions and sizes are ejected from gun primers and that these particles interact with the propellant grains during main charge ignition. This explicit ignition phenomenon is thought to be incompatible with the implicit treatment of primer function in conventional interior ballistics codes and models. Generally, the primer efflux is treated as a hot gas that evolves from a specified region in the model's representation of the gun chamber (usually along the chamber centerline and near the breech). What amounts to an igniter table is arrived at by experimental means and by careful calibration of the interior ballistics simulation using gun firing data. With the advent of multidimensional, multiphase interior ballistics codes which employ coupled Eulerian-Lagrangian schemes to explicitly treat both the gas and solid phase, the time is ripe for a primer model that is commensurate with the availability of such an interior ballistics model. Progress in the development of a primer model that is compatible with the ARL-NGEN3 interior ballistics code and small-caliber weapons is described herein. The model is based on the One Dimensional Turbulence modeling approach that has recently emerged as a powerful tool in multiphase simulations. Initial results are shown for the model run as a stand-alone code and are compared to recent experiments with small-caliber primers.
Author: Publisher: ISBN: Category : Ballistics, Interior Languages : en Pages : 36
Book Description
There is significant experimental evidence that burning particles of various chemical compositions and sizes are ejected from gun primers and that these particles interact with the propellant grains during main charge ignition. This explicit ignition phenomenon is thought to be incompatible with the implicit treatment of primer function in conventional interior ballistics codes and models. Generally, the primer efflux is treated as a hot gas that evolves from a specified region in the model's representation of the gun chamber (usually along the chamber centerline and near the breech). What amounts to an igniter table is arrived at by experimental means and by careful calibration of the interior ballistics simulation using gun firing data. With the advent of multidimensional, multiphase interior ballistics codes which employ coupled Eulerian-Lagrangian schemes to explicitly treat both the gas and solid phase, the time is ripe for a primer model that is commensurate with the availability of such an interior ballistics model. Progress in the development of a primer model that is compatible with the ARL-NGEN3 interior ballistics code and small-caliber weapons is described herein. The model is based on the One Dimensional Turbulence modeling approach that has recently emerged as a powerful tool in multiphase simulations. Initial results are shown for the model run as a stand-alone code and are compared to recent experiments with small-caliber primers.
Author: G. M. Faeth Publisher: ISBN: Category : Languages : en Pages : 6
Book Description
Two drop/gas interactions important in the near-injector dense region of sprays are being studied: (1) turbulence modulation, which is the direct generation or modification of turbulence by drop motion, and (2) secondary drop breakup, an important rate-controlling process in dense sprays. Effects of turbulence modulation were measured in homogeneous flows generated by particles falling in stagnant air and water baths. The flow was analyzed with a simple stochastic approach, involving linear superposition of randomly-arriving particle velocity fields. Guided by the theory, unified correlations of turbulence properties were achieved for the measurements. Further progress requires more information about particle wake properties at modest Reynolds numbers in turbulent fields: this is the main focus of current work. Secondary drop breakup is being studied using a shock tube and various drop generators, emphasizing near-limit breakup which is most relevant to dense sprays. Work thus far has concentrated on definition of deformation and shear breakup regimes. This will be followed by study of breakup dynamics and outcomes using holocinematography instrumentation that was recently developed in this laboratory. Keywords: Multiphase flow, Homogeneous turbulence, Drop breakup. (jhd).
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The accuracy of numerical predictions for gas/liquid two-phase flows using Computational Multiphase Fluid Dynamics (CMFD) methods strongly depends on the formulation of models governing the interaction between the continuous liquid field and bubbles of different sizes. The purpose of this paper is to develop, test and validate a multifield model of adiabatic gas/liquid flows at intermediate gas concentrations (e.g., churn-turbulent flow regime), in which multiple-size bubbles are divided into a specified number of groups, each representing a prescribed range of sizes. The proposed modeling concept uses transport equations for the continuous liquid field and for each bubble field. The overall model has been implemented in the NPHASE-CMFD computer code. The results of NPHASE-CMFD simulations have been validated against the experimental data from the TOPFLOW test facility. Also, a parametric analysis on the effect of various modeling assumptions has been performed.
Author: H. J. Gibeling Publisher: ISBN: Category : Languages : en Pages : 54
Book Description
A two-dimensional implicit interior ballistic computer code (ALPHA) has been developed to solve the turbulent two-phase flow in a gun tube beginning with primer discharge and ending with the projectile exiting the tube. The detailed prediction of flow properties in a gun barrel during firing would aid in the understanding and prevention of both gun barrel erosion and catastrophic gun failures. The governing partial differential equations and constitutive relations are presented for the two-phase, axisymmetric, turbulent flow in a gun tube with a rotating projectile. Results have been obtained for the two-dimensional, two-phase flow in a gun tube with a noncombusting particulate phase. The initial conditions for this case were uniform except for a small gas phase region near the projectile base. The computed results obtained demonstrate the feasibility of making two-dimensional, two-phase predictions for the flow in a gun tube. This procedure also provides a framework for the development and evaluation of two-phase flow turbulence models and constitutive relations which are appropriate for a multidimensional prediction scheme. (Author).
Author: Barry J. Azzopardi Publisher: ISBN: 9781567003147 Category : Condensation Languages : en Pages : 331
Book Description
Gas-liquid flows, arising as it does out of Master level and post experience courses, is particularly suitable for these audiences. However, book will also be a valuable source to researchers, not only to new readers coming to the subject for the first time, but also to those more experienced who will gain new insights from its contents. Amongst its aims are to bring together communality of features in two-phase flow across flow patterns and geometries and to put new material into the context of earlier work showing how early and later descriptions have a common root. The book introduces the basic methods used for two phase design methods, particularly for pressure drop. It goes on to introduce flow patterns and the physics of the transitions between them. It goes on to examine the major flow patterns, concentrating on annular flow in vertical pipes. It finishes with chapters on geometries other than pipes, including pipe junctions.
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Author: Daniel Khalitov
Author: G. M. Faeth
Author: Liang-Shih Fan
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Author: J. T. Jurewicz
Author: H. J. Gibeling
Author: Barry J. Azzopardi