Predicting the Peak Pressure from the Curved Surface of Detonating Cylindrical Charges

Abstract

Trinitrotoluene (TNT) equivalency depends on knowing the relative strength of different explosives compared to TNT. However, most past work has been carried out only using spherical charges, whereas most military ammunition is cylindrical in shape. It is known that in certain directions, cylindrical charges give an enhanced blast close in when compared to that of spherical charges. This paper examines data for cylindrical explosive charges from the literature for Composition B and pentolite and then describes experimental work carried out on cylindrical PE4 charges. Analysis of the free air experimental and literature data shows that close into the curved side of a cylindrical charge it is possible to predict the peak pressure using an equation of the form Peak pressure = K mass/distance 3 , where K is an explosive dependent constant; 2695 Pa m 3 kg À1 for Composition B, 2498 Pa m 3 kg À1 for pentolite and 2565 Pa m 3 kg À1 for PE4, for length to diameter ratios of between 2 : 1 and 10 : 1. For a scaled distance (distance/mass 1/3 ) of less than 3.5 m kg À1/3 , the results are very accurate. This means that, provided data for cylindrical charges of TNT is obtained, a simple method of determining the TNT equivalency of a cylindrical charge, perpendicular to the curved surface is given by TNT equivalence = K explosive /K TNT . For a more accurate prediction at a scaled distance of greater than 3.5 m kg À1/3 a cubic equation of the form Peak pressure = K 1 Z À3 + K 2 Z À2 + K 3 Z À1 has been found to apply where Z = distance/mass 1/3 and the coefficients K 1 , K 2 and K 3 depend on the explosive type.

Predicting Blast Waves from the Axial Direction of a Cylindrical Charge

“…Previous work by the authors [26][27][28] has studied the shock wave from the curved surfaces of cylindrical and disc charges, which lead to empirical methods for predicting the peak pressure and impulse in the radial direction for cylindrical charges.…”

“…For charges, where L/D ! 2, then close into the charge (Z < 3.5 m kg À1/3 ) the peak overpressure, P, in the radial direction is given by [26]:…”

“…To take into account the pressure further out, where the shocked waves have healed to that of a sphere, the authors developed an equation for all distances, given by [26]: where C' 1 , C' 2 , and C' 3 are explosive dependent constants. For cylinders and discs combined, close into the charge (Z < 3.5 m kg À1/3 ) the peak overpressure in the radial direction is [28]:…”

Influence of a point of charge initiation on parameters of cylindrical charge explosion on rigid surface

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Воздушный взрыв цилиндрических зарядов ВВ исследовался во многих работах как экспериментально [1][2][3], так и теоретически [4,5].Достаточно полную информацию по параметрам наземного взры-ва цилиндрических зарядов конечной длины можно найти в работах [6,7].Что касается влияния положения точки инициирования на оси сим-метрии цилиндрического заряда на параметры наземного взрыва, то каких-либо данных по этому вопросу в открытой литературе авторам найти не удалось.Настоящая работа является попыткой восполнить этот пробел. Для этого с помощью метода конечных элементов проводилось численное моделирование взрыва цилиндрического заряда из троти-ла (ТНТ) массой m 0 = 100 кг, плотностью ρ = 1630 кг/м 3 , диаметром d 0 = 2r 0 = 200 мм и высотой h 0 = 1952,8 мм, расположенного верти-кально на жесткой поверхности, моделирующей землю.

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“…Воздушный взрыв цилиндрических зарядов ВВ исследовался во многих работах как экспериментально [1][2][3], так и теоретически [4,5].…”