Verification and Validation in Computational Fluid Dynamics and Heat Transfer: PTC 61 (original) (raw)
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Combustion and Flame, 2020
The effect of chemistry modeling on the flow structure and quenching limits of detonations propagating into reactive layers bounded by an inert gas is investigated numerically. Three different kinetic schemes of increasing complexity are used to model a stoichiometric H 2-O 2 mixture: single-step, three-step chainbranching and detailed chemistry. Results show that while the macroscopic characteristics of this type of detonations e.g. velocities, cell-size irregularity and leading shock dynamics, are similar among the models tested, their instantaneous structures are significantly different before and upon interaction with the inert layer when compared using a fixed height. When compared at their respective critical heights, h crit , i.e. the reactive layer height at which successful detonation propagation is no longer possible, similarities in their structures become apparent. The numerically predicted critical heights increase as h crit, Detailed � h crit, 3-Step < h crit, 1-Step. Notably, h crit, Detailed was found to be in agreement with experimentally reported values. The physical mechanisms present in detailed chemistry and ne
Mathematical modeling of detonation initiation via flow cumulation effects
Progress in Propulsion Physics. EUCASS advances in aerospace sciences book series. V. 8. / [Edited by M. Calabro, L. DeLuca, S. Frolov, L. Galfetti, O. Haidn]. – Moscow: Torus Press, 2016. – P. 389 – 406., 2016
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2015
Detonation is a complex phenomenon that consists of a shock w ave coupled to reaction zone moving at a high-speed velocity. It has issues in many engineering scie nces such as safety and explosion, aerospace propulsion systems (pulse-, rotatingand oblique-detona ti engines). Detonation wave propagating in a narrow channel filled with a reactive mixture exhibits di fferent flow features and hydrodynamics instabilities with boundary layers effects. The flow resist ance can lead to a detonation velocity deficit compared to the ideal Chapman-Jouguet detonation velocity and can eventually cause the failure of the detonation. Detonation are unstable for most known gaseous c mbustible mixtures. These multidimensional instabilities provide an essential mechanism for de tonation propagation. Different mechanisms were proposed to explain the velocity deficit. Zel’dovich [1 ] proposed an analytical model based on a one-dimensional formalism in which drag forces and heat los ses are considered ...
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Acta Astronautica, 1974
A simplified theory of blast initiation of detonations in clouds of fuel in gaseous or droplet form is developed and agrees with the experiments described below. The flow is at first dominated by the strong blast wave but transition from blast to detonation behavior occurs near a critical radius r. where the blast energy and the heat of combustion contained in r < r. are equal. The complex flow in this transition region cannot be determined analytically. In the simplified theory the details of the transition region are ignored but the flow is represented by the self-similar solution for a strong blast wave for r < r. and by the self-similar detonation solution for r > r..
Gaseous detonations—A selective review
Progress in Energy and Combustion Science, 1991
lThis review confines itself to available information on gaseous detonations, including those in aerosols, clouds of flammable dusts and hybrid mixtures, from the standpoint of safety of chemical processing plant. In so doing, it examines recent extensions to work based on the concept of an ideal front with losses (non-ideal theory), showing how this may be applied to derive guidelines on the effects of tube diameter, of wall roughness and of initial pressure of the mixture on the velocity of a steady front. Further extension to the prediction of limits is considered for conditions likely to be experienced in actual plant, where walls are unlikely to be smooth and the presence of inert particles in the explosive medium is a possibility. However, the shortcomings of such an approach in dealing with the interactions of a real front with a complex component of plant is recognised. The experimental techniques which have been used to reveal the complex nature of real fronts are reviewed, prior to a description of studies of the structure of fronts which propagate transversely across the leading front and on how this structure is influenced by the properties of the explosive medium. Finally, experimental work on both non-reactive shocks and detonations in changing configurations of confinement is examined, in terms of possible measures for both reducing the destructive potential of a detonation and obtaining reliable design criteria for chemical plant. CONTENTS I. Introduction 328 2. Non-Ideal Detonations 2.1. Opening remarks 2.2. Detonation mechanisms in rough tubes 2.3. Theoretical considerations 2.4. Momentum and heat losses 2.5. Determination of momentum losses from shock attenuation 2.6. Detonations with homogeneous and boundary layer ignition 2.7. Influence of wall roughness on detonation velocity 2.8. Critical pipe diameter 2.9. Detonation in gaseous suspensions of inert particles 2.10. Detonation of gaseous mixtures in presence of evaporating particles 2.11. Comparison of experimental data with non-ideal unidimensional theory 2.12. Analysis of experimental data on dust clouds 3. Experimental Techniques 3.1. Opening remarks 3.2. Soot track method 3.3. Use of rings and gauges 3.4. Optical methods 3.5. Ionisation methods 4. Real Detonation Fronts 4.1. Opening remarks 4.2. Wave systems created by diffraction of shocks in inert media and their relationship to detonations 4.3. Uni-dimensional models of detonations 4.4. Initiation and the origin of structure 4.5. "Galloping' waves 5. Interactions of Wave Structure with Changes in Confinement 5.1. Opening remarks 5.2. Diffraction of a detonation at an abrupt increase in area 5.3. Methods of reducing and rendering more uniform local pressures 5.4. Reflection of detonation waves 6. Conclusions 364 Acknowledgements References 327
Numerical analysis of the explosion of gas tanks using computational fluid dynamics
Revista IBRACON de Estruturas e Materiais, 2023
Buildings are composed of several systems, each with specific designs and regulations to ensure that constructions are safe and viable. Many residential, commercial, and industrial buildings have systems with gas central storage, which must be subjected to strict safety criteria to avoid accidents. In addition to the safety mechanisms provided by manufacturers, designers of these gas central storage must consider other devices to reduce explosion risk and mitigate the damaging blast effects. Explosions are physical-chemical phenomena that are characterized by the sudden expansion of a material and, consequently, energy release. When an accidental explosion occurs, much damage is caused by the shock wave and fragments. In the case of pressure vessels, a mechanical explosion can occur. Studying this explosion is essential to developing a more reliable, safe design for surrounding buildings and its users. This work aims to study the effects of gas tank explosions. In this study, the Autodyn computational tool based on fluid dynamics (CFD) is used. This software allows the modeling of complex explosion scenarios and the evaluation of blast wave parameters. For each numerical model, the overpressure levels outdoors and indoors are evaluated. The results indicated how the wave overpressures are distributed in different scenarios, and from them, it was possible to analyze the damaging levels.
Mathematical Models and Computer Simulations, 2011
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