TY - JOUR
T1 - Ablative thermal protection systems
T2 - Pyrolysis modeling by scale-bridging molecular dynamics
AU - Harpale, Abhilash
AU - Sawant, Saurabh
AU - Kumar, Rakesh
AU - Levin, Deborah
AU - Chew, Huck Beng
N1 - Funding Information:
The authors acknowledge the support provided by NASA ESI Grant No. NNX16AD12G-2016-00147, as well as computational time provided by NASA/Pleiades (award no. STMD-16-676), TACC (award no. TG-MSS130007), and the Blue Waters sustained-petascale computing project which is supported by the National Science Foundation (awards OCI-0725070 and ACI-1238993) and the state of Illinois. Blue Waters is a joint effort of the University of Illinois at Urbana-Champaign and its National Center for Supercomputing Applications.
Funding Information:
The authors acknowledge the support provided by NASA ESI Grant No. NNX16AD12G-2016-00147 , as well as computational time provided by NASA/Pleiades (award no. STMD-16-676 ), TACC (award no. TG-MSS130007 ), and the Blue Waters sustained-petascale computing project which is supported by the National Science Foundation (awards OCI-0725070 and ACI-1238993 ) and the state of Illinois . Blue Waters is a joint effort of the University of Illinois at Urbana-Champaign and its National Center for Supercomputing Applications.
Publisher Copyright:
© 2017 Elsevier Ltd
PY - 2018/4
Y1 - 2018/4
N2 - Pyrolysis of a phenolic polymer is a well-known heat removal mechanism in charring ablators, but the process has not been well-quantified. Here, we perform scale-bridging molecular dynamics (MD) simulations based on a reactive-force-field (ReaxFF) potential to elucidate the pyrolysis kinetics of a highly crosslinked phenolic formaldehyde resin. We show that bulk pyrolysis starts at temperatures of ∼500 K, and exhibits a temperature dependence that follows the Arrhenius law. The pyrolysis process initiates with the removal of –OH functional groups and –H atoms from aromatic C rings within the bulk phenolic resin to release H2O, followed by breaking of these C rings to release C-based fragments. Using the pyrolysis rates from MD simulations, we develop a thermal material response model applied to predict the heat transfer within a charring syntactic foam ablator. Our model predictions of the char thickness and temperature distributions, under a variety of heat loads, are in good agreement with prior experiments.
AB - Pyrolysis of a phenolic polymer is a well-known heat removal mechanism in charring ablators, but the process has not been well-quantified. Here, we perform scale-bridging molecular dynamics (MD) simulations based on a reactive-force-field (ReaxFF) potential to elucidate the pyrolysis kinetics of a highly crosslinked phenolic formaldehyde resin. We show that bulk pyrolysis starts at temperatures of ∼500 K, and exhibits a temperature dependence that follows the Arrhenius law. The pyrolysis process initiates with the removal of –OH functional groups and –H atoms from aromatic C rings within the bulk phenolic resin to release H2O, followed by breaking of these C rings to release C-based fragments. Using the pyrolysis rates from MD simulations, we develop a thermal material response model applied to predict the heat transfer within a charring syntactic foam ablator. Our model predictions of the char thickness and temperature distributions, under a variety of heat loads, are in good agreement with prior experiments.
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U2 - 10.1016/j.carbon.2017.12.099
DO - 10.1016/j.carbon.2017.12.099
M3 - Article
AN - SCOPUS:85040310408
SN - 0008-6223
VL - 130
SP - 315
EP - 324
JO - Carbon
JF - Carbon
ER -