Visualization of shock wave and detonation wave

2003 ◽  
Vol 6 (3) ◽  
pp. 210-210
Author(s):  
T. Obara ◽  
S. Ohyagi
Keyword(s):  
Shock Wave ◽  
Detonation Wave

scholarly journals Thermal detonation wave in liquid lead – water mixture

2021 ◽  
Vol 2088 (1) ◽  
pp. 012027
Author(s):  
A V Kapustin ◽  
V I Melikhov ◽  
O I Melikhov ◽  
B Saleh ◽  
D V Finoshkina
Keyword(s):  
Heat Transfer ◽  
Shock Wave ◽  
Detonation Wave ◽  
Boundary Conditions ◽  
Internal Structure ◽  
Interfacial Friction ◽  
Liquid Lead ◽  
Water Mixture ◽  
Friction Heat ◽  
Closing Relations

Abstract It was developed the model of thermal detonation in a mixture of continuous liquid lead and dispersed steam/water particles. Stationary equations of mass, impulse and energy conservations laws for multiphase continuum are applied to describe internal structure of thermal detonation wave. They are supplemented by closing relations describing interfacial friction, heat transfer, and fragmentation. Conditions at leading shock wave and at Chapman-Jouguet plane are used as boundary conditions.

Numerical Research on the Toroidal Shock Wave Focusing Detonation Initiation

2019 ◽  
Author(s):  
Xiang Chen ◽  
Ningbo Zhao ◽  
Hongtao Zheng ◽  
Xiongbin Jia ◽  
Shizheng Liu ◽  
...  
Keyword(s):  
Shock Wave ◽  
Detonation Wave ◽  
Detonation Initiation ◽  
Operating Conditions ◽  
Initiation Mechanism ◽  
Wave Focusing ◽  
Jet Flame ◽  
Rotating Detonation Engine ◽  
Detonation Engine ◽  
Shock Wave Focusing

Abstract Pressure gain combustion (PGC) is considered to be a potential technology to increase the cycle efficiency of gas turbine. As one viable candidate for PGC, rotating detonation engine (RDE) draws more attention due to its significant advances in continuous mode of operation. In practical, one of the basic challenges for RDE application is to reliably initiate detonation wave. For this purpose, both detonation initiation mechanism and enhancement approach are urgently needed to be understood. In this work, a toroidal shock wave focusing detonation initiator is presented. On this basis, the two-dimensional numerical simulations are carried out to investigate the detonation initiation characteristics by using the toroidal shock wave focusing. All of the flame acceleration, shock wave focusing, detonation wave forming and propagation are analyzed in detail. The numerical results show that the toroidal shock wave focusing initiator developed in this study can rapidly realize the detonation initiation over a short distance and performs significantly better than the traditional smooth or obstructed tube based imitators under different operating conditions. Under the same operating condition, the novel developed initiator decreases time of 59.2% and distance of 84.7% for the smooth tube based initiator, and time of 52% and distance of 78.9% for the obstructed one. Besides, the multi-fields analysis indicates that both the local explosion induced by shock wave focusing in concave cavity and the entrainment vortex generated by shock wave and jet flame in front of diaphragm are important mechanisms to initiate detonation wave. The present study is expected to enhance the understanding of the physical mechanism of shock wave focusing detonation initiation and contribute to the development of detonation propulsion technology.

On Generation of Ultra-High Pressure by Converging of Underwater Shock Waves

1998 ◽  
Vol 120 (1) ◽  
pp. 51-55 ◽  
Author(s):  
S. Itoh ◽  
S. Kubota ◽  
S. Nagano ◽  
M. Fujita
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Detonation Wave ◽  
Simulation Method ◽  
Ceramic Materials ◽  
Underwater Shock Wave ◽  
Water Chamber ◽  
Metallic Compounds ◽  
Underwater Shock ◽  
Graph System

The characteristics of a new assembly for the shock consolidation of difficult-to-consolidate powders, such as inter-metallic compounds or ceramic materials, were investigated by both the experimental method and numerical simulation method. The assembly consists of an explosive container, a water chamber, and a powder container. Once the explosive is detonated, a detonation wave occurs and propagates, and then impinges on the water surface of the water chamber. After that, there occurs immediately an underwater shock wave in the water chamber. The underwater shock wave interacts with the wall of the chamber during its propagation so that its strength is increased by the converging effect. We used the usual shadow graph system to photograph the interaction process between detonation wave and water. We also used a Manganin piezoresistance gage to measure the converged pressure of the conical water chamber. Finally, we numerically investigated, in detail, the converging effects of the various conical water chambers on the underwater shock waves. The experimental results and the correspondingly numerical results agree quite well with each other.

Specifics of generating explosively formed projectiles of variable shape from metal liners

2019 ◽  
Author(s):  
P.V. Kruglov ◽  
V.I. Kolpakov ◽  
I.A. Bolotina
Keyword(s):  
Shock Wave ◽  
Aspect Ratio ◽  
Detonation Wave ◽  
Variable Shape ◽  
Internal Surfaces ◽  
Planar Shock ◽  
Wave Generator ◽  
Planar Shock Wave ◽  
Metal Liner ◽  
A Charge

We propose using charges generating explosively formed projectiles of variable shape to remotely demolish structurally unsound concrete or brick walls of buildings and other structures. The paper considers the charges required, their design and operation. The operation of such a charge involves the explosive material accelerating a metal liner, covering a distance of up to several hundred charge diameters. The metal liner deforms while moving and assumes a compact shape. We used variable thickness copper liners, the external and internal surfaces of which are formed by a combination of spherical surfaces. A planar shock wave generator featuring a variable detonation wave slope is considered as the initiation system for the charge. We present the results of numerically simulating our explosive charge operation in order to determine how charge parameters affect performance. We estimated charge performance via two projectile parameters: its shape and velocity. The study also evaluated the effect of the planar shock wave generator slope on the projectile shape. We obtained projectile velocity and aspect ratio as functions of the slope of the converging detonation wave. We determined that decreasing the slope of the converging detonation wave front leads to an increase in the aspect ratio and velocity of the explosively formed projectile.

scholarly journals Explosion waves and shock waves III-The initiation of detonation in mixtures of ethylene and oxygen and of carbon monoxide and oxygen

1935 ◽  
Vol 152 (876) ◽  
pp. 418-445 ◽  
Author(s):  
William Payman ◽  
H. Titman ◽  
Jocelyn Field Thorpe
Keyword(s):  
Shock Wave ◽  
Carbon Monoxide ◽  
Shock Waves ◽  
Detonation Wave ◽  
Wave Speed ◽  
Gas Mixtures ◽  
Gas Mixture ◽  
And Shock Waves ◽  
Long Run ◽  
Detonating Gas

This series of papers has so far dealt mainly with non-maintained or partially maintained atmospheric shock waves, and only incidentally with the fully maintained "detonation" wave. It is generally accepted that the detonation wave in an explosive gas mixture is a shock wave produced by the rapid combustion of the mixture, sufficiently intense to cause almost instantaneous ignition of the gas through which it passes, and continuous maintained by the combustion thereby started. An account of some preliminary experiments, using the "wave-speed" camera to record the movement of the flame and of the invisible shock waves in front of the flame in gas mixtures prior to detonation, has already been given by one of us. Those experiments related mainly to hydrogen-oxygen and methane-oxygen mixtures whose aptitude to detonate may be regarded as moderate, for the continuation of the work, mixtures with oxygen have again been used, but a more readily detonating gas, ethylene, was chosen. Experiments were also made with carbon monoxide, because the flame usually requires a comparatively long run before detonation is established. These two gases have the advantage, not shared by hydrogen and methane, that their predetonation flames are sufficiently actinic for good records to be obtained by direct photography for comparison with corresponding "wave-speed" records. All gas mixtures used were saturated with water vapour.

Numerical Research on the Toroidal Shock Wave Focusing Detonation Initiation

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Xiang Chen ◽  
Ningbo Zhao ◽  
Hongtao Zheng ◽  
Xiongbin Jia ◽  
Shizheng Liu ◽  
...  
Keyword(s):  
Shock Wave ◽  
Detonation Wave ◽  
Detonation Initiation ◽  
Operating Conditions ◽  
Initiation Mechanism ◽  
Wave Focusing ◽  
Jet Flame ◽  
Rotating Detonation Engine ◽  
Detonation Engine ◽  
Shock Wave Focusing

Abstract Pressure gain combustion (PGC) is considered to be a potential technology to increase the cycle efficiency of gas turbine. As one viable candidate for PGC, rotating detonation engine (RDE) draws more attention due to its significant advances in continuous mode of operation. In practical, one of the basic challenges for RDE application is to reliably initiate detonation wave. For this purpose, both detonation initiation mechanism and enhancement approach are urgently needed to be understood. In this work, a toroidal shock wave focusing detonation initiator is presented. On this basis, the two-dimensional numerical simulations are carried out to investigate the detonation initiation characteristics by using the toroidal shock wave focusing. All of the flame acceleration, shock wave focusing, detonation wave forming, and propagation are analyzed in detail. The numerical results show that the toroidal shock wave focusing initiator developed in this study can rapidly realize the detonation initiation over a short distance and performs significantly better than the traditional smooth or obstructed tube based imitators under different operating conditions. Under the same operating condition, the novel developed initiator decreases time of 59.2% and distance of 84.7% for the smooth tube based initiator, and time of 52% and distance of 78.9% for the obstructed one. Besides, the multifield analysis indicates that both the local explosion induced by shock wave focusing in concave cavity and the entrainment vortex generated by shock wave and jet flame in front of diaphragm are important mechanisms to initiate detonation wave. This study is expected to enhance the understanding of the physical mechanism of shock wave focusing detonation initiation and contribute to the development of detonation propulsion technology.

On the Supersonic Combustion of Hydrogen around a Conical Obstacle Considering Variable Specific Heats with Application to Scramjets

2015 ◽  
Vol 811 ◽  
pp. 162-166
Author(s):  
Sorin Berbente ◽  
Daniel Eugeniu Crunteanu ◽  
Corneliu Berbente
Keyword(s):  
Shock Wave ◽  
Detonation Wave ◽  
Numerical Method ◽  
Supersonic Combustion ◽  
Detonation Waves ◽  
Specific Heats ◽  
Combustion Speed ◽  
Combustion Of Hydrogen

One proposes a combined analytical-numerical method for the supersonic combustion around a conical obstacle, considering variable specific heats with temperature. One important aspect is to avoid the dissociation what is not possible if normal detonation waves (of Chapman-Jouguet type) occur. The Clarke model where the detonation wave is separated in a shock wave and a deflagation wave is able to reduce the temperature. Here conical waves are used. In order to characterize the combustion speed and intensity, new parameters are proposed. A comparison with the Chapman-Jouguet combustion is also presented.

On the direct initiation of a plane detonation wave

1986 ◽  
Vol 408 (1834) ◽  
pp. 129-148 ◽  
Keyword(s):  
Shock Wave ◽  
Detonation Wave ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Combustible Gas ◽  
Direct Initiation ◽  
Time Domains ◽  
History Of ◽  
Plane Detonation

It is assumed that energy is transferred at a rapid rate through a plane wall into a spatially uniform and initially stagnant combustible gas mixture. This action generates a shock wave, just as it does in an inert mixture, and also switches on a significant rate of chemical reaction. The Navier-Stokes equations for plane unsteady flow are integrated numerically in order to reveal the subsequent history of events. Four principal time domains are identified, namely ‘early’, ‘transitional’, ‘formation’ and ‘ZND’. The first contains a conduction-dominated explosion and formation of a shock wave; in the second interval the shock wave is responsible for the acceleration of chemical activity, which becomes intense during the ‘formation’ period. Finally a wave whose structure is in essence that of a ZND detonation wave emerges.

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