1. No category

School of Aerospace Engineering
Radiation and Gas Dynamics
• Radiation often calculated in conjunction with CFD,
e.g., NASA’s Data Parallel Line Relaxation (DPLR)
• Uncoupled solutions
– CFD solution calculated without radiation
– radiation heat flux determined in “post-processing” with
RTE solver
– valid in optically thin limit with low qr/ho and weak
coupling to surface heat transfer
• Coupled solutions
– CFD and RTE solved simultaneously (or iteratively)
– computationally intensive
– band models offer potential for significant speed-up (if
significant molecular band involvement, e.g.,
IR/moderate temperatures)
AE6050
Flows with Radiation -1
Copyright © 2013 by Jerry M. Seitzman. All rights reserved.
School of Aerospace Engineering
Hypersonic Flow over Cylinder
• Mach 31 air with limited species (N2, O2, N, O, NO)
• Coupled-calculation
40,000K
20,000K
241K
Flows with Radiation -2
Copyright © 2013 by Jerry M. Seitzman. All rights reserved.
P. Bauman, R. Stogner, Multiphysics
Coupling, UT Austin (2009)
AE6050
1
School of Aerospace Engineering
Hypersonic Flow over Cylinder
• Mach 21 air with limited species (N2, O2, N, O, NO)
• Coupled-calculation
10,000K
6000K
245K
Flows with Radiation -3
Copyright © 2013 by Jerry M. Seitzman. All rights reserved.
P. Bauman, R. Stogner, Multiphysics
Coupling, UT Austin (2009)
AE6050
School of Aerospace Engineering
Hypersonic Flow over Cylinder
• Temperature
• Pressure
• Radiation
Flows with Radiation -4
Copyright © 2013 by Jerry M. Seitzman. All rights reserved.
P. Bauman, R. Stogner, Multiphysics
Coupling, UT Austin (2009)
AE6050
2
School of Aerospace Engineering
Example: CEV
• Re-entry of Crew
Exploration Vehicle at
peak heating condition
• Radiation calculated with
and without coupling
Feldick, Modest and Levin, “Closely
Coupled Flowfield–Radiation
Interactions During Hypersonic
Reentry,” J. Thermophysics and Heat
Transfer 25 (2011)
AE6050
Flows with Radiation -5
Copyright © 2013 by Jerry M. Seitzman. All rights reserved.
School of Aerospace Engineering
Along stagnation line
radiation reduces
standoff distance
Example: CEV Heat flux on CEV body
peaks
qc downstream
off
stag.
point
qr
peaks
at
stag.
point
• Coupling lowers predicted convective wall qc by ~5% and radiative
qr by ~19%; radiation accounts for > 1/3rd of heat flux to body
• Reduction in T at edge of b.l. due to radiative cooling more than
offsets b.l. heating due to radiative absorption close to surface
Flows with Radiation -6
Copyright © 2013 by Jerry M. Seitzman. All rights reserved.
Feldick, Modest and Levin, J. Thermophysics and
Heat Transfer 25 (2011)
AE6050
3
School of Aerospace Engineering
Example: Huygens Probe - Titan
• Entry of Huygens Probe (Huygen-Cassini mission) to
Saturn’s moon Titan
• Radiation calculated with and without coupling
Hollis et al., “Prediction of the Aerothermodynamic Environment of the
Huygens Probe,” AIAA2005-4816
AE6050
Flows with Radiation -7
Copyright © 2013 by Jerry M. Seitzman. All rights reserved.
School of Aerospace Engineering
Example: Huygens Probe - Titan
• Methane composition has significant effect on (increases)
radiative heat flux to body (production of CN)
• Radiative loading 2-3 convective heat transfer
Flows with Radiation -8
Copyright © 2013 by Jerry M. Seitzman. All rights reserved.
Hollis et al., “Prediction of the Aerothermodynamic
Environment of the Huygens Probe,” AIAA2005-4816
AE6050
4