Registration and simulation of air blast pressure of a detonating charge above ground


  • Almström Henrik

Publish date: 2003-01-01

Report number: FOI-R--0819--SE

Pages: 62

Written in: Swedish


The possibility of simulating the pressure wave, generated by a detonating charge in air, and its interaction with structures, has been rapidly improved during the last years. To obtain a good simulation a good description of the detonation process in the explosive, a good description of the properties of the reaction products, a good description of the properties of the air and a good description of the surrounding structures, such as the ground, are required. For a full description of the phenomena a simulation of the turbulent processes along surfaces and a simulation of the combustion of the reaction products with air are needed. Often the turbulent process can be dismissed in which case the phenomena can be described by the Euler equations. These are implemented in the computer codes LS-Dyna and Autodyn where immovable cells are used. In order to calibrate the above computer codes regarding the equation of states and the demand of numerical accuracy a number of measurements have been conducted to obtain experimental data. Six charges have been detonated at different heights above the ground and the pressure at the ground has been recorded at different horizontal distances from ground zero. One simulation with LS-Dyna has been conducted regarding the case of a detonation at the height of 1 m. With a cell width of around 10 mm the obtained pressures are about 10% too low. Two simulations with Autodyn have been performed for the cases of detonations at the height of 1 m and 2 m. With small cells (typical dimension 2 mm) the agreement with experiment is satisfactory. Optimising the material parameters in the simulation will improve the agreement.