Explosive wave

The chief danger and main source of error in a combustion is that of moving the Bunsen forward a little too rapidly and so causing much of the substance to burn very rapidly, so that a flash-back occurs. This usually causes an explosion wave to travel back along the tube towards the purification train, some carbon dioxide and water vapour being carried with it. If these reach the packing of the purification train they will, of course, be absorbed there and the results of the estimation will necessarily be low. 

The second indication is a faint smoke-like cloudiness in the zone of the tube which is being heated by the Bunsen this is readily visible as the interior of the tube is normally quite clear and bright. This is a later stage of development of the flash-back than the rise of pressure, already mentioned, and should be counteracted by moving the Bunsen immediately to the point of the combustion tube where heating was commenced. In either case the Bunsen should then be moved slowly forwards as before. A flash-back is attended by the deposition of carbon particles, carried back by the explosion wave, on the cold walls of the tube. Care should be taken that these are completely burnt off as the Bunsen is slowly moved forward again. 

Gorev, V. A., and Bystrov S. A. 1985. Explosion waves generated by deflagration combustion. Comb., Explosion and Shock Waves. 20 (6) 614-620. 

Knall-saure, /. fulminic acid, -silber, n. fulminating silver, -welle, /. explosion wave, shock wave, -zucker, m. (Expl.) nitro-saccharose. -ziinder, m. detonator, -zund-mittel, n. detonating priming, knapp, a. close, tight, narrow scanty exact. Enappe, m. miner. 

Without going into detail with regard to this very interesting subject, it may be stated that "the velocity of the explosion wave in a gaseous mixture is nearly equal to the velocity of sound in iAe burning gases". 

On the basis of this relationship between the velocity of sound in the burning gases and the velocity of explosion, Professor H. B. Dixon calculated the velocity of the explosion wave in certain gaseous mixtures and also determined it experimentally, with the results gfiven below —... 

Detonation, Explosive Wave Shaping by Delayed. M.M. Sultanoff discussed this subject at the Proceedings of the First Symposium on Detonation Wave Shaping (sponsored by Picatinny Arsenal) at the Jet Propulsion Laboratory, Pasadena, California, June 5-7, 1956... 

Detonation (and Explosion), Langweiler Model or Langweiler Wave See under DETONATJON (AND EXPLOSION) WAVES... 

In 1888, the American, Professor C.E. Munroe (Ref la), while working at the Naval Torpedo Station at Newport, Rl, observed that if a block of cast high explosive with letters indented on the surface was placed with the letter-side against a metal plate and exploded, the letters would be reproduced indented on the metal plate. This phenomenon was explained by the fact that two or more explosive waves will resolve into a resultant wave which is of much greater force than any of the original waves. 

Bleakney, JApplPhys 19, 670-78(1948) (Attenuation of spherical shock waves in air) 12a) W.B. Cybulski, PrRoySoc 197A, 51-72(1949) (Explosion waves and shock waves) 13) H.A. Bethe E. Teller, "Deviation from Thermal Equilibrium in Shock Waves , BRL Rept X-117 ( l949)... 

B. Koch, BerBunsengesPhysChem 70 (9-10)(1966) CA 66, 1995(1966), "Studies of Detonation and Shock Wave Fronts by Using Microwaves . Its abstract is given in Ref 83 under DETONATION (AND EXPLOSION) WAVES 85) C.W. Hamilton 8c G.L. Schott, "Post-Induction Kinetics in Shock Initiated H2-O2 Reactions , 11th-SympCombstn (19o7), pp 635-43 86) P.A. 

DETONATION (AND EXPLOSION) WAVES (Their Relotion to Detonation Front, Detonation Zone, and Reaction Zone)... 

Dremin Pokhil (Ref 58) detd deton wave parameters in TNT, RDX, NG and NMe. Zubarev Telegin (Ref 76) detd parameters in some condensed expls and Hazal Comburini (Ref 78) calculated characteristics of explosion waves in pure and diluted Hydrazoic Acid... 

Note The above discussion on "Steady-State, Plane Detonation Wave taken from the book of Taylor contains some equations which are listed under DETONATION (AND EX. PLOSION) THEORIES and also at the beginning of this Section entitled DETONATION (AND EXPLOSION) WAVES. Although it is realized that these equations are repetitions, they are not eliminated but just referred in order to preserve the cohesion of the description... 

This subject is discussed at the beginning of this section entitled DETONATION (AND EXPLOSION) WAVES and in the following Refs 27, 40, 51, 65, 103 104... 

Booklet), pp 44- 8 (Detonation and shock waves) 20) E. Dubois, MAF 21, 369—93 (1947) (Investigation by means of a piezoelectric apparatus the forces of in stantaneous pressures produced when explosion waves meet an obstacle) 20a) R.H. Cole, "Underwater Explosions , Princeton UnivPress, Princeton, NJ (1948), Chapter 3 21) P. 

W.B.. Cybulsky et al, PrRoySoc 197A, 51-72 (1949) (Explosion waves and shock waves). 22a) H. Eyring et al, Chem Revs 4 69 (1949) (See in the text under "Radius of the Curvature of the Detonation Wave Front 23) G.I. Taylor,... 

Explosive Wave Shaping by Delayed Detonation, BRL 1022(1957) 49a) J.M. Majowicz... 

I. Hazal J. Comburini, CR 255, 509- 11 (1962) CA 57, 140 43 (1962) (Calculation of characteristics of explosion waves in pure or diluted Hydrazoic Acid) 79) J.A. Nicholls E.K. Dabora, "Recent Results on Standing Detonation Waves, 8th Symp Combstn (1962), 644-55 80) D.F. Homig, "Energy Exchange... 

Taylor (1952), p 174 Detonation Zone. See under DETONATION (AND EXPLOSION) WAVES (Their Relation to Detonation Front, Detonation Zone, and Reaction Zone) See also W.G. Penney, PrRoySoc 204A, pp 5-6 (1950) and C.G. 

N. Man son, La Theorie Hydrodynamique et le Diametre Limite de Propagation des Ondes Explosives (Hydrodynamic theory and the maximum limiting diameter of propagation of explosion waves), pp 586—92... 

In other words, investigation of explosives involves a study of these aspects. For example, an investigation of the potential energy involves study of thermochemistry of the chemical compound in question. Further, the power and sensitiveness of an explosive depend on properties such as heat of formation and heat of explosion . An investigation of the feature (2) involves measurement of the rate of propagation of explosion waves and all phenomena in the proximity of detonating mass of the explosive. This rate of decomposition largely determines the pressure... 

Although contact with organic matter, or local overheating, readily initiates explosion waves in chlorine monoxide, the slow decomposition can conveniently be observed between about 60° and 140° C., and has been studied by Hinshelwood and Prichard and Hinshelwood and Hughes, f... 

The ease with which explosion waves are set up in chlorine monoxide can be explained. The heat of activation is 21,000 calories. The heat of reaction is 32,000 calories. Simplifying the calculation by supposing the reaction to consist of the one stage 2 C120 = 2 Cl2 + 02, in which the 32,000 calories are liberated, it may be inferred that the products have an excess energy of 32,000 -I- 21,000... 

The applicability of the collision theory to this reaction is therefore specially interesting. If explosion waves are easily propagated in the gas it seems not impossible that, even in the slow decomposition, quite long reaction chains might be set up, the activation of a single pair of molecules being sufficient to cause the decomposition of some hundreds or thousands. But if this happened the calculated and observed values of E could not have been even approximately concordant. 

The homogeneous reaction between carbon monoxide and oxygen has only been observed in the explosion wave. The explosion takes place much more readily in the presence of steam than in its absence. Dixon explained this by showing that the series of reactions C0+H20 = C02 + H2 2 H2 + 02 = 2 H20... 

It is true that they are very rare. The reaction 2C0 + 02 = 2C02 proceeds, not homogeneously, but as a wall reaction under ordinary conditions. The explosion wave, which is set up at higher temperatures, must indeed depend upon a homogeneous change, but this, as Dixon has shown, requires the presence of water, whereby the termolecular reaction is probably replaced by a series of bimolecular changes... 

There are indicated in Table I two types of possible waves one, which produces a pressure increase, density increase, and velocity decrease, and the other, which produces a pressure decrease, density decrease, and a velocity increase. For nonadiabatic waves the former are classified as detonations or explosion waves, and the latter are classed as deflagrations. 

The authors who discovered detonation noted that in order of magnitude the detonation velocity is close to the molecular velocity of the reaction products, to the velocity of sound in the products, and to the propagation velocity of strong explosive waves. These comprise, in embryo form, the ideas which were later developed by many different scientists. 

Chapmann developed a hydrodynamic theory of detonation along the lines used earlier by Riemann, Rankine and Hugoniot to construct a theory of shock (explosive) waves in a chemically inert gas. 

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