TY - JOUR
T1 - Diffusion flame studies of solid fuels with nitrous oxide
AU - Nardozzo, Paige K.
AU - Connell, Terrence L.
AU - Boyer, J. Eric
AU - Yetter, Richard A.
AU - Young, Gregory
N1 - Funding Information:
The US Air Force Office of Scientific Research (AFOSR) under Grant AFOSR FA9550-13-1-0004 supported this research. Paige K. Nardozzo is now at the Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723; Terrence L. Connell Jr. is now at the Naval Surface Warfare Center-Indian Head Explosive Ordnance Disposal Technology Division, Indian Head, MD, 20640; Gregory Young is now at Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061.
Publisher Copyright:
© 2020, Begell House Inc.. All rights reserved.
PY - 2020
Y1 - 2020
N2 - Counterflow diffusion flame experiments were conducted to investigate hydroxyl-terminated polybutadiene (HTPB) solid fuel combustion under varied pressure environments from 0.1 to 2.2 MPa using nitrous oxide (N2 O) as the oxidizer. A numerical model was developed to analyze the flame structure and predict regression rates. Results show solid fuel regression rates to increase with pressure for a fixed oxidizer momentum flux. The flame structure thins due to faster kinetics and shifts toward the regressing fuel surface with increasing pressure. The diffusion flame is positioned on the oxidizer side of the stagnation plane, which also shifted toward the fuel surface with increasing pressure. Flame temperature increases with pressure as well, due to decreasing radical formation, increasing the surface temperature gradient, resulting in enhancement of solid fuel pyrolysis. Heat release from N2 O decomposition and pyrolyzed fuel oxidation occurs in two distinct stages at atmospheric pressure, while at elevated pressure (1.83 MPa) the exothermic peak associated with oxidation is distributed over a spatial domain thinner than at 0.1 MPa, but contains many small regions of isolated exothermicities. The flame structure with N2 O exhibits a similar structure as O2-HTPB diffusion flames in the spatial regions where N2 O was not present because of decomposition. Leakage of O2 and NO into the fuel pyrolysis zone also decreases with increasing pressure. Predicted regression rates with N2 O are approximately 34% lower than those with O2. A comparison of counterflow fuel regression rates with subscale hybrid motor fuel regression rates are in good agreement when the rates are extrapolated based on oxidizer mass flux.
AB - Counterflow diffusion flame experiments were conducted to investigate hydroxyl-terminated polybutadiene (HTPB) solid fuel combustion under varied pressure environments from 0.1 to 2.2 MPa using nitrous oxide (N2 O) as the oxidizer. A numerical model was developed to analyze the flame structure and predict regression rates. Results show solid fuel regression rates to increase with pressure for a fixed oxidizer momentum flux. The flame structure thins due to faster kinetics and shifts toward the regressing fuel surface with increasing pressure. The diffusion flame is positioned on the oxidizer side of the stagnation plane, which also shifted toward the fuel surface with increasing pressure. Flame temperature increases with pressure as well, due to decreasing radical formation, increasing the surface temperature gradient, resulting in enhancement of solid fuel pyrolysis. Heat release from N2 O decomposition and pyrolyzed fuel oxidation occurs in two distinct stages at atmospheric pressure, while at elevated pressure (1.83 MPa) the exothermic peak associated with oxidation is distributed over a spatial domain thinner than at 0.1 MPa, but contains many small regions of isolated exothermicities. The flame structure with N2 O exhibits a similar structure as O2-HTPB diffusion flames in the spatial regions where N2 O was not present because of decomposition. Leakage of O2 and NO into the fuel pyrolysis zone also decreases with increasing pressure. Predicted regression rates with N2 O are approximately 34% lower than those with O2. A comparison of counterflow fuel regression rates with subscale hybrid motor fuel regression rates are in good agreement when the rates are extrapolated based on oxidizer mass flux.
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U2 - 10.1615/IntJEnergeticMaterialsChemProp.2020028356
DO - 10.1615/IntJEnergeticMaterialsChemProp.2020028356
M3 - Article
AN - SCOPUS:85086985104
SN - 2150-766X
VL - 19
SP - 73
EP - 93
JO - International Journal of Energetic Materials and Chemical Propulsion
JF - International Journal of Energetic Materials and Chemical Propulsion
IS - 1
ER -