Simulation of the Effects of an Air Blast Wave - ELSA - Europa

value in [13]). These results show that the maximum pressures are smaller, and the arrival time ishigher. To conclude, it seems that the influence of the parameter γ towards a better material law,would not lead to better results.4.7.2 Values for γ, E 0, ρThere are different values for the parameters γ , E 0 and ρ of the ideal gas equation (16) in theliterature. These differences should be considered and assessed.Case Used values (CON8) (CON15 CON16γ 1.35 1.176 1.4E 0 2.1978e5 4.37e5 2.5e5ρ 1.300 1.300 1.293Table 9: Parameters γ, E 0 and ρThe maximum pressure resulting from the model CON16 is higher, the arrival time is smaller butthe difference with model CON8 is very small. The difference from model CON15 to model CON8is very small, too. Therefore the choice of the parameter values for the air doesn’t have a biginfluence.4.7.3 Parameters for the explosiveThe parameters for the JWL equation (15) could also have an influence on the results. Thecalculations are made with the parameters used by AUTODYN and Shin [21] (see Table 2)(CON17, CON18). It is found that, overall, the influence of the chosen parameters is small. Theresults for the standard parameters of AUTODYN are nearly the same. The maximum pressure withthe values of Shin is at a distance of 0.40 m approximately 10 % higher. The arrival time is 5 %smaller; the impulse is 1 % higher.4.7.4 Burn mass fractionThe burn mass fraction has an influence on the behaviour in the explosive (see chapter 4.1). Themodel CON8 is calculated with the burn mass fraction (B S = 2.5, model CON19) to test theinfluence on the behaviour of the air. The difference between the calculations with and without burnmass fraction is very small and represents for the overpressure, the impulse and the duration of thepositive phase only 1%. The arrival time is approximately 10 % higher.51