Characteristics of the Shock Wave Generated in Air by a Blasting Cap,

摘要

The propagation of the shock wave generated in air by a very small surface explosion, a commercial No. 6electric blasting cap,has been studied. A large number of time-resolved pressure histories were recorded with piezoelectric transducers at distances over the range of 3.05to 80.8meters from the explosion point. The observed range of peak air shock pressures was from .02bars down to .0002bars. Comparisons with TNT surface burst data for much larger explosions show that the peak pressure-distance attenuation exponents are the same. Based on these pressure-distance data,the yield of the No. 6electric blasting cap used is approximately 0.4grams of TNT. Even at the lowest peak pressures measured,the wave shapes are characteristic of typical airblast shock waves. An essentially triangular positive pressure phase is followed by a negative pressure phase of much lower amplitude and longer duration;this is unlike the signatures of sonic booms which are highly symmetric. The effect of the asymmetry on the energy density spectrum of the blasting cap is also discussed. (Author)