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

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pressure is reached if the sonic velocity of the reaction gases reaches the detonation velocity. Thevolume at the Chapman-Jouguet-point isVCJ= − P(20)CJ12ρ0dThe term F 1 of the burn mass function intends to spread the burn front over several elements. Thesecond term should control the releasing of the energy. Interestingly, MSC-Dytran uses only theterm (19), whereas ABAQUS uses only one burn mass function( − )⎧ t t1d⎪ if t > t1Fb = ⎨ BS ⋅le⎪⎩ 0 if t ≤ t1(21)In this formula B S is the constant that controls the width of the burn wave (set to a value of 2.5) andl e is the element length. This function is very similar to (18).A 3D model of explosive is used to show the influence of the different burn mass fractions (Figure12, explosive4), whose different components can be compared in Figure 10 and Figure 11. Theinfluence of the term (21) is visible. The slope of the pressure peak decreases with F b , and thearrival of the pressure peak is later. The calculations with EUROPLEXUS do not show an influenceof the second term (F 2 ). Both curves are almost identical.LS-DYNA uses the functions (18) and (19) for calculations with theMAT_HIGH_EXPLOSIVE_BURN model. The input syntax allows calculations with bothfunctions (beta=0) or only with the function (19) (beta=1). The model in LS-DYNA was built withhexahedral with an element size of 0.001 m. The results of a 3D model show that the burn massfraction in LS-DYNA reduces also the slope of the pressure peak. Nevertheless, the differencebetween the calculations with beta=0 and beta=1 is negligible. The differences of the calculationsbetween EUROPLEXUS and LS-DYNA are the smaller peak in LS-DYNA and the higher pressurevalues behind the peak (here for a distance less than 0.04 m). The impulses are nearly the same (LS-DYNA 2.07 10 8 Pa sec, EUROPLEXUS 2.00 10 8 Pa sec).Therefore, the burn mass fraction is for the future work implemented only with the equation (21).22
2.0E+101.6E+10without burn mass fractionburn mass fraction Fbburn mass fraction Fb and F2LS-DYNA beta=0LS-DYNA beta=1Pressure [Pa]1.2E+108.0E+094.0E+090.0E+000 0.01 0.02 0.03 0.04 0.05 0.06Distance [m]Figure 10: Influence of the burn mass fraction in EUROPLEXUS (t=7 10 -6 sec)2.0E+101.6E+10EUROPLEXUS bmf=0EUROPLEXUS bmf=2.5LS-DYNA beta=0LS-DYNA beta=1Pressure [Pa]1.2E+108.0E+094.0E+090.0E+000.04 0.05 0.06 0.07 0.08 0.09 0.1Distance [m]Figure 11: Influence of the burn mass fraction in EUROPLEXUS (t=1.4 10 -5 sec)Another EOS for explosive is the “Ignition and Growth Reactive Model” based on Tarver et al.[23]. This model can also be used for the burning of propellant (deflagrations).23
Page 1 and 2: Simulation of the Effectsof an Air
Page 3 and 4: Distribution ListLechner S.Anthoine
Page 5 and 6: 1 IntroductionThis work is being co
Page 7 and 8: • Far zone. The blast wave result
Page 9 and 10: Figure 2: Model of Kingery [14] wit
Page 11 and 12: 2.2.3 ImpulseThe impulse of the air
Page 13 and 14: Figure 5: Different parameters for
Page 15 and 16: 250200Impulse from KingeryImpulse w
Page 17 and 18: the specific heat ratio and the spe
Page 19 and 20: determined with a fluid pre-calcula
Page 21: From this asymptotic form it can al
Page 25 and 26: Case opening d pyra d ex,in d ex,en
Page 27 and 28: Pressure [Pa]2.4E+102.0E+101.6E+101
Page 29 and 30: 5.0E+094.0E+09EUROPLEXUS x=0.105EUR
Page 31 and 32: Cased pyr /d ex,in /d ex,end /d air
Page 33 and 34: Figure 21: Comparison of a coarse w
Page 35 and 36: CON9This model has approximately th
Page 37 and 38: 4E+7Max. pressure [Pa]3E+72E+7Kinge
Page 39 and 40: Case Size of the model Description
Page 41 and 42: CUB4This model uses a finer mesh th
Page 43 and 44: 6. Complete the volumes by adding t
Page 45 and 46: Figure 33: Maximum pressures versus
Page 47 and 48: experimental values is obtained wit
Page 49 and 50: 4.6.3 Arrival TimeThe arrival time
Page 51 and 52: value in [13]). These results show
Page 53 and 54: Modell airl bBubbleBubbleBubbleTNT
Page 55 and 56: Several calculations are done with
Page 57 and 58: 3. Calculation of the factor α bub
Page 59 and 60: quadratic. Therefore, the size of t
Page 61 and 62: 400Impulse [Pa sec]300200.Kingery 5
Page 63 and 64: 5 = hemispherical detonation (half
Page 65 and 66: 9 References[1] Alia, A.; Souli, M.
Page 67 and 68: 10 Apendix10.1 EUROPLEXUS Codedyms.
Page 69 and 70: CALLMECVAL(GET_FMT(6),NEWMAT%MATVAL
Page 71 and 72: 10.2 Miscellaneous codeairblastresu
Page 73 and 74:
else{ //Kingerydouble t=log10(z);do
Page 75 and 76:
maxar=0;REPE I0 (NBEL vges);ar = as
Page 77 and 78:
*defining the surfaces around the a
Page 79 and 80:
lpyr1 = p1 d ppy2;lpyr2 = p1 d ppy3
Page 81 and 82:
lpyr2 = p1 d ppy3;lpyr3 = p1 d ppy4
Page 83:
*Cube intermediaire (centre=o0 et a
Page 86:
The mission of the JRC is to provid
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Simulation of the Effects of an Air Blast Wave - ELSA - Europa

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