Propagation characteristics of blast shock waves in low-pressure environment

The blast loading from a detonation of a high explosive charge at high altitude is quite different from that at sea level. Due to diminished ambient pressure, the damage caused by the blast load may be more minor at high altitude. However, the shock wave parameters at diminished ambient pressure have not yet been thoroughly studied. In this research, experiments were carried out to study the relation between ambient air pressure and shock wave parameters. The explosion experiments were carried out in a sealed explosion chamber with an initial pressure of 95 kPa, 74 kPa, and 57 kPa. For these three atmospheric conditions, the history profiles of incident shock wave pressure generated by TNT charges of 106 g and 292 g were recorded. The influence of ambient pressure and temperature on the shock wave parameters was analyzed through numerical simulations. By analyzing the experimental and numerical data, it was found that ambient pressure is the main factor affecting the shock wave parameters, while the effect of temperature is not so obvious. Furthermore, based on the analysis of experimental data, formulas for evaluating shock wave overpressure, specific impulse, and arrival time using the Sachs variables are given, and the shock wave parameters at an altitude of 5000 m are calculated using these formulas. The observed maximum reduction in the shock wave overpressure was 23%, in specific impulse 27%, and in arrival time 12%, compared to the results calculated at sea level. The results can be applied to blast-resistant analyses of buildings in low-pressure environment.