Explosion , Effects of Blast and Shock Waves

Detonation (and Explosion), Effects of Blast and Shock Wave on Structures. As this subject was not discussed in Vol 2 of Encycl, under BLAST EFFECTS IN AIR, EARTH AND WATER , pp B180-L to B184-R, there is given here a brief description as taken from the book of Robinson (1944), where it is described in detail on pp 45-53 

An explosion or detonation produces both an air blast and a shock wave in the air. The air blast consists of the air in violent motion in a general direction away from the site of the expln and in a condition of extreme turbulence. This degree of turbulence may be imagined by estimating a Reynolds Number of it, devised by Engl scientist Osborne Reynolds (1842-1912), to describe the effect of velocity phenomena in connection with flow of liquids. If k is Reynolds Number, d=diameter of moving stream, u = its linear velocity, p = its density and = its viscosity, 

The push of an expln against a wall is the product of the pressure times the time of duration of the push. This product is called impulse and can be expressed as  

Impulse is the most important factor in determining the resulting behavior of the wall. Method of its calcn is given on pp 48-52 of Robinson s book 

In addn to the distance of the structure from the expln, the vibration period or frequency of the structure affects its behavior in a blast. The nearer the frequency of the structure to that of the shock wave, the more likely it is to vibrate in sympathy with it and therefore to suffer more damage. Since most buildings vibrate betw 1 and 10 vibrations per second and the frequency of violent explns is usually greater than 10, the damage from shock waves due to sympathetic vibrations is not likely to be great 

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Explosion, Effects of Blast and Shock Waves on Structures. See Vol 4, pp D256 D257... 

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