Experimental study on the TNT equivalence for blast parameters in a confined space

Abstract

The concept of TNT (Trinitrotoluene, C₇H₅N₃O₆) equivalence is often invoked to evaluate the performance and predict the explosion parameters of different types of explosives. However, due to its low prediction accuracy and limited application range, the use of TNT equivalence for predicting explosion parameters in a confined space is rare. Compared with explosions in free fields, the process of explosive energy release in a confined space is closely related to various factors such as oxygen balance, combustible components content, and surrounding oxygen content. Studies have shown that in a confined space, negative oxygen balance explosives react with surrounding oxygen during afterburning, resulting in additional energy release and enhanced blast effects. The mechanism of energy release during afterburning is highly complex, making it challenging to determine the TNT equivalence for blast effects in a confined space. Therefore, this remains an active area of research. In this study, internal blast experiments were conducted using TNT and three other explosives under both air and N₂ (Nitrogen) conditions to obtain explosion parameters including blast wave overpressure, quasi-static pressure, and temperature. The influences of oxygen balance and external oxygen content on energy release are analyzed. The author proposes principles for determining TNT equivalence for internal explosions while verifying the accuracy of obtained blast parameters through calculations based on TNT equivalence. These findings can serve as references for predicting blast performance.