Cassady, Amy

NASA Technical Reports Server

5/11/2012
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National Aeronautics & Space Administration
Lyndon B. Johnson Space Center
Houston, TX 77058
CAP Aerothermodynamics Lessons Learned
Amy Cassady
Applied Aerosciences and CFD Branch
Page 2CEV Aeroscience Project  -- Amy Cassady (281-483-7488)
Background
The CEV Aeroscience Project (CAP) aerothermodynamics team 
provide aerothermodynamic environments for ascent abort and 
reentry using high fidelity computation, ground testing and flight 
testing
• At the start of the project, the intention was to rely heavily on computational 
methods, however wind tunnel testing and engineering methods have been 
used heavily in the construction of the database
• The database is versatile to cover a wide range of trajectories and to an 
extent, changes in geometry
https://ntrs.nasa.gov/search.jsp?R=20120008850 2019-08-30T20:26:11+00:00Z
5/11/2012
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Page 3CEV Aeroscience Project  -- Amy Cassady (281-483-7488)
Background
Re-entry Aerothermodynamic Environments
Environment is simulated in ground test facilities by designing tests to 
investigate specific phenomenon
Page 4CEV Aeroscience Project  -- Amy Cassady (281-483-7488)
Aerothermodynamics Analysis
CM Smooth Heatshield Heating
Computational Fluid Dynamics
Smooth Body Radiative Heating
LAV Computational Fluid Dynamics CSM Ascent Abort Direct Simulation 
Monte Carlo
CM Smooth Backshell Heating 
Computational Fluid Dynamics
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Page 5CEV Aeroscience Project  -- Amy Cassady (281-483-7488)
Aerothermodynamic Testing
Heatshield Features
Reaction Control Jets
High Gradient RegionsHeatshield Features
Heatshield Roughness Backshell Features
Page 6CEV Aeroscience Project  -- Amy Cassady (281-483-7488)
Database Construction
Abort Environments CM Design Environments
CSMLAV
Smooth Body Heating DatabaseSpecialized Heating Models
Cavities
RCS
On‐Orbit Plumes
High Altitude
Radiation Convection (CFD)
Integration Tool
Separation
Ramp/Protuberances Catalytic Overshoot Roughness/Blowing
Gap Heating
Venting
Heatshield Features
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Page 7CEV Aeroscience Project  -- Amy Cassady (281-483-7488)
Major Database Components
Component Type Validation Source
Smooth Body Convective CFD derived/Engineering Orbiter, Apollo, Wind Tunnel Testing
Smooth Body Radiation High Fidelity Wind Tunnel Testing, Heritage
Cavity Heating Empirical/Engineering Orbiter heritage, Wind Tunnel Testing
RCS Heating Empirical/RGD-DSMC/Empirical Apollo, Wind Tunnel Testing
Venting Engineering Heritage
High Altitude RGD-DSMC Heritage
Gap Heating Empirical Orbiter
Ramps/Protuberances Empirical/Engineering Heritage, Wind Tunnel Testing
Catalytic Overshoot CFD derived Orbiter data
Roughness/Blowing Empirical/Engineering Wind Tunnel Testing
Heatshield Features CFD/Empirical Wind Tunnel Testing
Separation Line CFD derived Wind Tunnel Testing
Page 8CEV Aeroscience Project  -- Amy Cassady (281-483-7488)
Lessons Learned
Integration with trajectory design is critical – environment indicators 
included in trajectory design help guide vehicle assessment
Integration with the Thermal Protection System design and 
assessment is critical
• TPS design and environment derivation are coupled for ablative material
• Know how the aerothermodynamic environments are being used
• Understand a design environment versus a realistic environment and when 
to use both
Be an active participant in vehicle trade studies or designs like this 
will come to fruition
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Page 9CEV Aeroscience Project  -- Amy Cassady (281-483-7488)
Lessons Learned
Protuberances, penetrations, gaps, local chemistry, control jets, 
roughness…all effect the system, do not underestimate their 
contributions to the total heat load and peak heat rate
Page 10CEV Aeroscience Project  -- Amy Cassady (281-483-7488)
Lessons Learned
CFD has a place in trade studies, predicting environments for smooth 
bodies and ground to flight traceability, but it isn’t ready for non-
smooth component analysis or highly unsteady wake flow
• Keystone wind tunnel test with more than 400 discreet measurements on the 
capsule backshell to understand penetrations/protrusions/RCS environments


CAP Aerothermodynamics Lessons Learned

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