Numerical simulations and field validation tests for shock waves' propagation

摘要

At the BAM test range in Horstwalde a number of field trials were conducted with a HE to investigate the free field propagation of shock waves and that resulting from reflection at structure surfaces. In addition, the behavior of the structure under the effect of the dynamic pressure waves after explosion was studied. For both the tests, (a) with a 30 cm thick re-inforced-concrete wall and (b) in free field, pressure was measured over the entire test duration with piezoelectric sensors at distances of 5. 10 and 15 m from the detonation center for a range of HE quantities. Apart from this, high speed footage of the tests was recorded as well. Corresponding to the field tests, numerical simulations of HE detonation were performed using APOLLO BLASTSIMULATOR. a CFD tool developed by Fraunhofer Institute for High-Speed Dynamics. Ernst-Mach-Institute. The accuracy of the simulation results as well as the computing times depend on the spatial grid resolution. The outputs of grid-independence study demonstrated that the peak pressure is higher and the pressure-rise is steeper for simulation runs with a finer grid. Remarkably however, the exponential pressure decline is independent of the grid resolution. Advantage was taken of this feature to obtain improved peak pressure values from comparatively coarser grids, in that curve-fitting was performed using the Friedlander Equation, which is well documented in literature. The simulation results for pressure-time histories were compared with the field-test results at the corresponding measurement positions. The two data sets showed good correlation in case of scaled distances greater than 5 Im/kg~（1/3） for both peak pressure and impulse values. This conclusion could be drawn for both trial-types: free-field and with reflection wall. The near field region, on the other hand, necessitates further investigation for the validation of numerical simulation.