Assessment Of Mach Stem Pressures: Comparison Of Experiments With Engineering And Eulerian Models

Laboratory scale tests conducted by Kisters and Kuder (2012) provide reflected pressure histories for a 1kg TNT charge detonated at 0.32m above a rigid surface. The pressure histories are measured 1m from the charge using a vertical array of pressure transducers to infer the height of the Mach Stem at this range. Two such vertical arrays, each with 9 pressure transducers at varying heights above the surface, were used, and the test was repeated three times. Four additional configurations with heights- of-burst (HOB) varying from 0.1 to 0.32m and standoff ranges of 0.9 to 1.2m were conducted, but not reported in the present reference. Examination of the measured wave forms allowed Kisters and Kuder to estimate the height of the Mach Stem, a.k.a. triple point, to within 60mm (vertical gauge spacing). The pressure histories from the vertical array measurements provide an opportunity to assess the accuracy of the LS-DYNA air blast engineering model referred to as LOAD_BLAST_ENHANCED, and results from simulations using the LS-DYNA Eulerian solver usually referred to as Multi-Material Lagrangian Eulerian (MM-ALE). In addition to comparisons of maximum pressure, and time-of-arrival (TOA), the time integrated pressure histories provide maximum impulses for comparison.