Reflection, shock wave

Figure B2.5.6. Temperature as a fiinction of time in a shock-tube experiment. The first r-jump results from the incoming shock wave. The second is caused by the reflection of the shock wave at the wall of the tube. The rise time 8 t typically is less than 1 ps, whereas the time delay between the incoming and reflected shock wave is on tlie order of several hundred microseconds. Adapted from [110].

The pyrolysis of CR NH (<1 mbar) was perfomied at 1.3 atm in Ar, spectroscopically monitoring the concentration of NH2 radicals behind the reflected shock wave as a fiinction of time. The interesting aspect of this experiment was the combination of a shock-tube experiment with the particularly sensitive detection of the NH2 radicals by frequency-modulated, laser-absorption spectroscopy [ ]. Compared with conventional narrow-bandwidth laser-absorption detection the signal-to-noise ratio could be increased by a factor of 20, with correspondingly more accurate values for the rate constant k T). 

In general, a reflected shock wave of 55 psi on a human for 400 milliseconds would be just about the tolerance limit [41] (see Table 7-25B). For a more detailed discussion of blast scaling and overpressure, see Ref [40]. 

Mach Stem. A shock wave or front formed above the surface of the earth by the fusion of direct and reflected shock waves resulting from an airburst. Also called mach wave and mach front... 

The loads from external near-surface burst explosions are based on hemispherical surface burst relationships. Peak pressure (P psi) and scaled. impulse Ci/W psi/lb ) are plotted vs. scaled distance (R/W ft/lb ). Roof and sidewall elements, side-on to the shock wave, see side-on loads (P and i ). The front wall, perpendicular to the shock wave, sees the much higher reflected shock wave loads (P and i ). An approximate triangular pressure-time relationship is shown in Figure 5a. The duration, T, is determined from the peak pressure and impulse by assuming a triangular load. Complete load calculations include dynamic loads on side-on elements, the effect of clearing times on reflected pressure durations, and load variations on structural elements due to their size and varying distance from the explosive source. 

Numerous determinations of the heat of formation of carbon difluoride, a transient intermediate in the production of PTFE, for example, have been made. The most recent one has combined kinetic and equilibrium approaches. The equilibrium C2F4 2CF2 was studied at 1150-1600 K at 0.07-46 bar in dilute argon mixtures using incident and reflected shock waves. The carbene concentration was monitored at 250 nm after a careful study of the extinction coefficient over a wide temperature range. Rate parameters were found for forward and back... 

Blast Effects Due to Reflected Shock Waves. See Vol 2, p B182-L... 

Detonation, Reflected Shock Waves in Air Blast. See Vol 2 of Encycl, p B182-L and Fig on p B183... 

G.L. Schott, "Chain Branching and Initiation Rates Measured by Spatially Integrated Light Emission During Reflected Shock-Wave Ignition , Ibid, pp 569-78... 

Detonation, Vulnerable Radii of Demolition. See Vol. 2,p B182-R under Blast Effect Due to Reflected Shock Waves... 

Blast Effectiveness of Various Explosives is given in Table on p B182 of Vol 2 Blast Effects Due to Reflected Shock Waves is given in Vol 2, p B182-L... 

Study of ignition in reflected shock wave of mixts of methane with air and inert diluents) Z3)R.H.Essenhigh J.Csaba, 9thInternCombustSymp, Cornell Univ,... 

It is known that ignition and expln of dangerous coal mine atmosphere depends on many factors, such as compn of mine atm, wt of charge of expl, induction period (time elapsed betw expln of charge and ignition of mine atm), temp of products of expln, presence of hot solid particles in products of expln, duration of flame, heating of mine atm due to adiabatic compression created by incident and reflected shock waves, etc. 

Problem 2 Will the reflected shock wave travelling with velocity 2000m/sec and creating pressure of 40atm ignite the firedamp previously heated to 737°K by incident shock wave ... 

Results of a kinetic and theoretical study of the unimolecular decomposition of cyclobutanol behind incident and reflected shock waves at 950-1450 K show that vinyl alcohol is produced through a biradical before isomerizing to acetaldehyde.40... 

The oxidation of o-, m-, and p-xylenes with oxygen-argon mixtures were measured behind reflected shock waves. The main reaction paths have been determined by sensitivity and flux analyses and have been used to explain the slight differences in the reactivity.253... 

The kinetics of the pyrolysis of CHC13 was determined behind incident and reflected shock waves at 1050-1600 K92. This decomposition was reported to be unimolecular and the process is an a,a-elimination CHC13 - CC12 + HC1. The Arrhenius parameters for this process are log A - 14.3, E = 228 kJmoT1. 

The incident and reflected shock-wave technique was employed for a kinetic study of the thermal decomposition of /-butyl bromide110. The substrate dehydrobrominated even at the highest temperature of 1050 K via a unimolecular four-membered cyclic transition state. The A factor and the activation energy obtained in different investigations were compared and, because of the small temperature range in each individual study, these data were combined in order to estimate more reliable Arrhenius parameters between 500 K and 1050 K. Thus ... 

T Width of compression zone cont Velocity or reflected shock wave... 

The thermal reactions of dihydrobenzo[c]furan 258 were studied behind reflected shock waves in a single pulse shock tube over the temperature range 1050-1300 K to lead to products from a unimolecular cleavage of 258 <2001PCA3148>. Intriguingly, carbon monoxide and toluene were among the products of the highest concentration, while benzo[f]furan, benzene, ethylbenzene, styrene, ethylene, methane, and acetylene were the other products. Trace amounts of allene and propyne were also detected. 

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