Blast Wave Characteristics in Air—One-Pound Hemispherical TNT Charge

An approximate measure of explosive yield may be obtained by determining the amount of energy that is transferred to the blast wave by the explosion products. An upper limit may be found by evaluating 

This actually represents the reversible work performed by the explosive system so that it overestimates the energy transferred to the blast wave. However, if each system is treated in a similar fashion, then 

TNT equivalents can also be obtained for compressed-gas systems in which a chemical reaction does not occur. For the ideal gas case in which a sudden expansion occurs from pressure to pressure P2 at temperature T, we have 

Arrival times, pulse durations, and impulses also follow the cube-root scaling law. Thus, 

The arrival time and pulse duration of the reference charge (Wq) are determined at Dq. Equation (4.46) is then used to determine the corresponding quantities for the charge at D. For example, the arrival time of the blast wave at a point 40 ft from an 8-lb TNT charge is found by first calculating Dq [=40(1/8) ] t ito) at this distance (Table VII) is 12.0 msec. Then the arrival time at Dj is 

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Table VII. Blast Wave Characteristics in Air—One-Pound Hemispherical TNT Charge...

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