A Method for Estimation of Blast Performance of RDX‐IPN‐Al Annular Thermobaric Charges

Abstract

AbstractThe objective of this research was to develop and to experimentally validate a method to predict the blast performance of thermobaric annular charges based on isopropyl nitrate‐aluminium and RDX‐isopropyl nitrate‐aluminium. Overpressure and thermal output were investigated in open air using piezoelectric pressure transducers, high speed visible and infrared imaging. Prediction of the explosive transformation of the annular thermobaric charge was computed by thermochemical code EXPLO5® using the Chapman‐Jouguet (ideal detonation) and non‐ideal Wood and Kirkwood (WK) detonation model. The Jones‐Wilkins‐Lee (JWL) parameters obtained in the calculations were used in hydrocode numerical simulation using AUTODYN® in order to predict the incident overpressure, total impulse and arrival time. Additional energy attributed to aluminium afterburning was used in order to simulate the post‐combustion phase. For isopropyl nitrate‐aluminium based charges, both BKW and WK models estimate correctly the peak overpressure and arrival time, while the total impulse was more accurately calculated by WK non‐ideal detonation model. For the RDX‐containing formulation, the prediction of peak overpressure, total impulse and arrival time are in agreement with the predictions obtained using WK non‐ideal detonation model with additional energy. The performances of the investigated thermobaric charges were compared with an equivalent mass charge of TNT, confirming both the expected higher total impulse and higher peak overpressures in the case of RDX‐isopropyl nitrate‐aluminium based thermobaric charges. Thermal measurements highlighted two distinct phases, an anaerobic phase and the post combustion of the thermobaric compositions. In terms of thermal output, the RDX‐isopropyl nitrate‐aluminium thermobaric based charge manifests superior performances.