Simultaneous photonic doppler velocimetry and ultra-high speed imaging techniques to characterize the pressure output of detonators

Abstract

Detonator output directed into both ambient air and polymethylmethacrylate (PMMA) windows is simultaneously investigated using ultra-high speed, time-resolved imaging and photonic Doppler velocimetry (PDV) measurements. In air, one-dimensional measurements of detonator cup position are made from timeresolved image sequences and compared to time-integrated velocity curves obtained from the PDV data. The results demonstrate good agreement that validates using the two methods concurrently to measure the motion of the detonator free-surface. In PMMA windows, instantaneous shock velocities are calculated from 1-D time-resolved measurements of shock position and known velocity-Hugoniot data are utilized to map the shock velocity calculations to corresponding values of mass velocity and shock pressure. Simultaneous PDV data describing the motion of the detonator cup/PMMA interface are used to determine the mass velocity and pressure at the interface, and to compare to the mass and shock pressures calculated from the imaging data. Experimental results are in good agreement with empirical detonation- and shock-interaction calculations, as well as 1-D numerical simulations.