Unsteady detonations resulting from first-order phase transformations

  • 138 Pages
  • 1.98 MB
  • English
Phase transformations (Statistical phy
Statementby Ronald Lee Rabie.
The Physical Object
Paginationx, 138 l.
ID Numbers
Open LibraryOL16755501M

Description Unsteady detonations resulting from first-order phase transformations PDF

A simple thermodynamic system is constructed having a single first order phase transformation. This system is shown to support self sustaining waves under a variety of boundary conditions given a metastable initial state. These waves are unsteady in any single inertial reference frame unless the boundary conditions are adjusted to generate the Chapman-Jouguet : Ronald Lee Rabie.

adshelp[at] The ADS is operated by the Smithsonian Astrophysical Observatory under NASA Cooperative Agreement NNX16AC86AAuthor: Ronald Lee Rabie. First-order phase transformations 3.

General characteristics of first-order transformations A re:tuber of second-order transitions discussed in this meeting involve a change in the vibrational mode or they are electronic transitions.

In contrast to this, many first-order transformations require movement of atoms over considerable. Purchase Detonation and Two-Phase Flow - 1st Edition. Print Book & E-Book. ISBNBook Edition: 1. Cite this paper as: Scott Stewart D., Aslam T., Yao J., Bdzil J.B. () Level-set techniques applied to unsteady detonation by: 4.

Disorder-driven first-order phase transformations: A model for hysteresis Karin Dahmen, Sivan Kartha, James A. Krumhansl,a) Bruce W. Roberts, James P. Sethna, and Joel D. Shoreb) Laboratory of Atomic and Solid State Physics, Cornell Universit;v, Ifhzu, New York S.C propulsion.

However, a thermostatic approach shows that unsteady detonations have the potential for generating more work than constant-pressure combustion.

The sub-sequent work focuses on speciflc engine concepts. A °ow path analysis of ideal steady detonation engines is conducted and shows that their performance is limited and. the models to slightly unsteady flow. There are a number of interesting consequences of these models, including cellular detonations (Stewart, Aslam & Yao ).

In this paper we present an alternative model for direct initiation that arises from a detailed analysis of the unsteady reaction-zone structure.

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Our analytical approach. A pulse detonation engine is an unsteady propulsive device in which the Unsteady detonations resulting from first-order phase transformations book chamber is cycle at relatively high frequency and/or using more than one combustion chamber operating out of phase.

again resulting in an increase in energy release rate and effective flame propagation velocity. Chapter 10 - 2 Phase transformation • Takes time (transformation rates: kinetics). • Involves movement/rearrangement of atoms. • Usually involves changes in microstructure 1.

“Simple” diffusion-dependent transformation: no change in number of compositions of phases. Detonation (from Latin detonare 'to thunder down/forth') is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it.

Detonations occur in both conventional solid and liquid explosives, as well as in reactive gases. The velocity of detonation in solid and liquid explosives is much higher.

Kapila, A. and Dold, J. W., b. “A theoretical picture of shock-to-detonation transition in a homogeneous explosive” 9th Symposium (International) on Detonation,pp. – Google Scholar. give examples of simple diffusive phase transformation. solidification of pure metal, allotropic transformations, recrystallisation and grain growth.

what happens to the number of phases present when materials undergo simple diffusive phase transformation. outline the process of tempering and the result. Lecture 3: First Order Phase Transitions The van der Waals equation for a gas is h PC a V2 i [V−b] DNkBT: (1) (The variable ais proportional to N2 and bto N, i.e.

aDN2aNand bDNbNwith a;NbNconstants). It can be motivated by rewriting it in the form PD NkBT V−b − a V2 (2) The V−bterm comes from estimating the “free volume” available.

work such techniques are used to study a general two-phase detonation model. In so doing, two-phase steady detonations have been studied in the same context as the extensive one-phase steady theory [40].

An outline of the two-phase detonation analysis of this work is now given. The unsteady. CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): The dynamics of one-dimensional detonations predicted by a one-step irreversible Arrhenius kinetic model with the inclusion of mass, momentum, and energy diffusion were investigated.

A series of calculations in which activation energy is varied, holding the length scales of diffusion and reaction constant, was performed. What is the evolution of first order phase transformation. nucleation, growth, coarsening.

What is coarsening. When the average size of second phase particles increases with time to decrease total surface free energy of system.

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During coarsening, the number of particles in the system increases/decreases. phase detonation theory. As opposed to unsteady DDT theory, which considers solutions to time- dependent partial differential equations, the steady two-phase detonation is described by the solution of ordinary differential equations.

This allows the use of the powerful technique of phase space anal. Unsteady Detonations Resulting from First-Order Phase Transformations. Article. Jan ; Ronald Rabie.

A simple thermodynamic system is constructed having a single first order phase. The results of computations of steady and unsteady detonation waves in a heterogeneous medium, i.e.

the mixture of liquid fuel drops and gaseous oxidi. Phase transitions are generally classified according to the Ehrenfest classification. The order of a phase transition is defined to be the order of the lowest-order derivative, which changes discontinuously at the phase boundary.

The first three orders are given in the figure. We shall discuss first-order. The flow behaviour presents similarities with non ideal detonations (Wood and Kirkwood in J Chem Phys –, ) and pathological detonations (Von Neuman in Theory of detonation waves. The detonation that is expected to occur unde - - totally confined conditions may be reduced to an unsteady, rapid deflagration with much les damage to the target.

The principal work presented in the report is the development of a three-dimensional unsteady flow model which can be used to predict whether detonation will. In chemistry, thermodynamics, and many other related fields, phase transitions (or phase changes) are the physical processes of transition between the basic states of matter: solid, liquid, and gas, as well as plasma in rare cases.

A phase of a thermodynamic system and the states of matter have uniform physical a phase transition of a given medium, certain properties of the. −Both originally used FCT (Boris & Book) unsteady −Front dynamics Detonation Transition in Gas Phase Combustion,” Comb.

Flame, in press, z Oran, E., Young, T. and Boris, J., “Application of Time-Dependent Numerical Methods to the Description of Reactive Shock Waves,”. A schematic of the wedge-induced oblique detonation in a two-phase fuel–air mixture is shown in Fig. the incoming supersonic sprayed fuel–air mixture flows past a wedge with angle θ w, an OSW with angle θ s triggers exothermic chemical reactions and subsequently induces an ODW with angle θ d downstream under a certain condition.

As scaled by the dashed lines, a two-dimensional. Dynamics of Detonations and Explosions: Explosion Phenomena (Progress in Astronautics & Aeronautics) [Kuhl, A. L., Leyer, J. C., Borisov, A. A., Sirignano, W. A.] on. A simple thermodynamic system, having a single first‐order phase transformation, is examined as an elementary explosive.

The energy needed to support self‐sustaining waves is stored in the volume change of the phase transformation. It is shown that this system can support the conventional viscous detonations as well as a set of unsteady eigenvalue detonations.

Of the two-phase mixture models used to study deflagration-to-detonation transition in granular explosives, the Baer–Nunziato model is the most highly developed. It allows for unequal phase velocities and phase pressures, and includes source terms for drag and compaction that strive to erase velocity and pressure disequilibria.

This book deals with the phenomenological theory of first-order structural phase transitions, with a special emphasis on reconstructive transformations in which a group-subgroup relationship between the symmetries of the phases is absent.

It starts with a unified presentation of the current approach to first-order phase transitions, using the. Numerical Study of Unsteady Detonation Wave Propagation in a Supersonic Combustion Chamber T.H. Yi, D.R. Wilson, and F.K. Lu Aerodynamics Research Center, Mechanical and Aerospace Engineering Department, BoxUniversity of Texas at Arlington, Arlington, TXUSA Abstract.

Propagating detonation waves in a supersonic °ow in one.Theory of first-order phase transitions Kurt Binder Institut fur Physik, Johannes-Gutenberg-Universitat Mainz, PostfachMainz, West Germany Abstract An introductory review of various concepts about first-order phase transitions is given.

Rules for classification of phase transitions as second or first order are discussed, as. In Chapter 2 of Nitinol: The Book, Tom introduces some basics principles of phase transformations in metals. As unusual as Nitinol is, the superelastic and shape memory properties driving these are a byproduct of phase transformations that are ubiquitous in virtually all materials.

Read on to learn more, including why Napoleon's Russian invasion failed because of a phase transformation.