Simulation Techniques

Abstract

Air blast phenomena scale over many orders of magnitude. The scaling laws described in Chap. 12 are limited by the type of explosive source, not by the scale of the phenomena being studied. A spherical blast wave reflecting from a flat plane can be scaled over more than 12 orders of magnitude. Blast wave reflection phenomena are independent of the scale at which they are studied. At the Ernst Mach Institute in Germany, tests are often conducted in the laboratory using 0.5 g charges of PETN. Special care must be taken to ensure accurate geometry and instrumentation dimensions because a small deviation at this scale may be significant at full scale. For example, a 1 m diameter boulder at the 8 kt scale becomes a 0.4 mm grain of sand at the half gram scale. Many of the advances in the understanding of blast waves can be directly attributed to the nearly infinite scalability of air blast phenomena. A number of methods have been developed which permit the study of blast wave phenomena at laboratory or at least at manageable scales.