Determining burn model parameters of ZPP using small scale tests

Zirconium potassium perchlorate (ZPP) is a primary explosive which possesses fast burning rates, desirable ignition characteristics, and high energy densities. Despite being widely used as the igniting propellant in an explosive train, its burning mechanism is not widely reported. In this work, the combustion model for ZPP is assumed to follow Vielle’s law. The parameters are calibrated and optimized based on measured combustion pressures from specially designed small scale tests. Two different diagnostics are explored (a) direct measurement in a confined fixture using pressure transducers and (b) indirect measurementusing polyvinylidene fluoride (PVDF) gauges.

While transducers directly measure the combustion pressure, the voltage signals obtained from the transducers were found to plateau, possibly due to the fixture design preventing deformation of the diaphragm in the transducer. Subsequently, PVDF gauges were considered due to its simplicity. Isochoric combustion pressures were determined from thermochemical equilibrium calculations and compared with test measurements. The burn model of ZPP was then calibrated and further optimized as more PVDF test data are attained. The calibrated burn model parameters act as inputs to the hydrodynamics model of an explosive train comprising of the ZPP stimulus, donor and acceptor explosives. With the calibrated burn model of ZPP, the response to different amounts of stimulus, acceptor and donor could be studied. This methodology can be applied to study the burn models of energetic materials with little reported reaction mechanisms.