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

250200Impulse from KingeryImpulse with b from KinneyImpulse with b from BakerImpulse with b by using pminImpulse [Pa sec]1501005000 2 4 6 8 10 12 14 16 18 20Scaled distance Z [m/kg 1/3 ]Figure 7: Decay parameter b – resulting impulse in comparison with the impulse from KingeryTherefore, the parameter b is next calculated using the impulse of the positive phase. Then, theresulting curve of b is similar to the curves of Kinney and Baker. The exponential trend line givenby Excel has the following equationb1.1975= 5.2777⋅ Z −(11)The pressure time curve that is built with this b doesn’t fulfil the minimal pressure in the negativephase. Sometimes the pressure p is smaller than the atmospheric pressure. This results in animpossible state of the air. Therefore, the approximation of the negative phase is done with abilinear curve shown in equation (12) and Figure 8 by using the values of the negative phase shownin section 2.2.4.⎛tt ⎞ dp= p0 + pmax⎜1 − ⎟ for t < td⎝ td⎠2 pntnp= p0− ( t− td) for t > td ∧ t < td+t22 pntnp = p0− ( t + t − t) for t > t + ∧ t < t + tt2p= p for t > t + t0nnbt−d n d d ndn(12)15