Experimental performance assessment of thermobaric explosives in free field and internal blast tests

In the present study, various test methods in the free field and confined explosions of cast HMX-based thermobaric explosives (TBX) and TNT are applied to quantify the explosion performance of TBX. The results show that the Mach reflection overpressure $\Delta p$ and impulse $I$ of TBX in the free field are much larger than those of TNT at the same relative distance from the explosion center. Based on the measured experimental data, semi-empirical formulas for calculating the overpressure at different distances from the TNT and TBX charges are derived. The fireball temperature and the duration of temperature higher than $1500^\circ$C of TBX are seen to be significantly greater. The measured peak pressure of the two explosives blast in an explosion tank are compared with the values predicted by modified calculation models, and the results are in good agreement. In addition, the quasi-static pressure generated by TBX in the explosion tank is $30.9\%$ higher than that of TNT, which obviously reveals thermobaric effects of TBX. Based on the overpressure and quasi-static pressure calculation model, the TNT equivalents of TBX are calculated to correctly evaluate the TBX performance. The related contents in this paper will guide the formulation and performance assessment of TBX.