Download Modeling HE Detonation

Modeling HE Detonation
• Muller, Shepherd, Chakraborty,
Dasgupta, Goddard
HMX
• Provide a detailed reaction
mechanism:
– 72 Species
– 445 Reactions
• Ultimately reduce (Eckett)
• Understand detonation on a
reaction by reaction basis
• Understand how additional
species (binder, aging, etc.)
alters detonation properties.
Starting Points
• GRI nitromethane mechanism
– 49 species
– 300 reactions
• Melius nitromethane mechanism
– 27 species
– 130 reactions
• Yetter RDX mechanism
– 48 species
– 240 reactions
• Guirguis nitromethane mechanism & data
• Chakraborty/Lin reaction modeling
Additional Species
NO 2
N
N
N
N
N
N
O2N
NO 2
N
N
O2N
NO 2
N
O2N
NO 2
NO 2
N
O2N
N
O2N
N
N
N
N
N
NO 2
N
N
O
N
O2N
H
H
C
N
O
NO 2
N
O2N
H
N
N
NO 2
N
O2N
N
N
O2N
H
N
C
O
H
H
N
N
Thermochemical Data
• B3LPY/6-31G** calculation
• Compute Cp, H, S from 3006000 K
• Fit to 14-term NASA form
HMX/RDX Combustion
Validation: Nitromethane Shock Data
Chemkin with Correct EOS
• CV uses Ideal Gas EOS
– Can’t describe high P,T
• Obtained CK-Real Gas
– BKW, vdW, Peng-Robinson
• BKW EOS:
PV  ZRT
Z  1  Xe  X
X
  n i ki
V(T   )
 , ,  ,   0.5, 0.174,11.85, 5160
DFT-MD Modeling of HE Initiation
• Understand how mechanical energy is transormed into
chemical energy
• Hypothesis that the H atoms are displaced more by the
shock wave than the heavy atoms.
• Run DFT/MD to investigate this.
Mechanism
Dimethyl nitramine
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