David Cormie

Incident and Normally Reflected Overpressure and Impulse for Detonations of Spherical High Explosives in Free Air

AbstractAir-blast parameters, including incident and reflected peak overpressures and impulses, and shock-front arrival times, are typically estimated for protective design using charts developed by Kingery and Bulmash. The charts underpredict incident and normally reflected peak overpressures and incident impulse near the face of the charge. Numerical analyses of detonations of spherical charges of trinitrotoluene in free air are performed using a verified and validated computational fluid dynamics (CFD) code to understand the shortcomings of current approaches for calculating incident and normally reflected overpressures and impulses, and for shock-front arrival time. New equations and design charts are proposed based on CFD calculations.

TNT Equivalency for Overpressure and Impulse for Detonations of Spherical Charges of High Explosives

Equivalency is often used to enable calculations of overpressures and impulses for explosives other than TNT. Equivalent mass factors are available for far-field detonations but none are available for near-field detonations. These reported factors are associated with incident overpressure and impulse and assumed appropriate for reflected overpressure and impulse. Numerical studies of TNT-equivalent mass factors for four high explosives (PETN, Composition B, Pentolite and Tetryl) for incident and normally reflected peak overpressure and scaled impulse are presented for a wide range of scaled distance 0.06 ≤ Z ≤ 40 m/kg1/3. Emphasis is placed on near-field detonations for which no reliable factors are currently available.

Reflection Coefficients and Reflected Scaled Impulses from Detonations of High Explosives as a Function of Angle of Incidence

AbstractIncident and reflected peak overpressures and reflected impulses are often used to compute blast loads on structures, components of structures, and objects. Reflection coefficients are used...