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Effects of Re-entry and Post-Landing Heating on the Orion Crew Module
Cabin Air Temperature
Ángel Álvarez-Hernández(281) 483-5234
angel.alvarez-hernandez-1@nasa.gov
Stephen Miller(281) 483-5504
stephen.w.miller@nasa.gov
Thermal & Fluids Analysis Workshop (TFAWS 2008)San Jose State University, San Jose, CA
August 18-22, 2008
Thermal & Fluids Analysis Workshop 2008 2
Topics
IntroductionModel DevelopmentEnvironmentsAnalysis CasesResultsConclusions
Thermal & Fluids Analysis Workshop 2008 3
Introduction
In addition to surviving re-entry, the Orion Crew Module (CM) must also provide a safe haven for the crew if a quick recovery is not possible.
The Orion project requires 36 hours of survival capability after a water landing.
The purpose of this analysis was to determine the cabin air temperature taking into account re-entry heating and soak-back, and the post-landing thermal environment.
Thermal & Fluids Analysis Workshop 2008 4
Model Development
Optical Properties
Backshell/Heat Shield on-orbit:
=0.3/0.3Re-entry to landing:
=0.9/0.9
Inner facesheet: (titanium)=0.2
TPS Stack-Up
Backshell (BS)AETB-8Titanium Honeycomb
Heat Shield (HS) dishPhenolic Impregnated Carbon Ablator (PICA)Titanium Honeycomb
Heat Shield (HS) shoulderPICATitanium Plate
Backshell
Heatshield shoulderHeatshield dish
Thermal & Fluids Analysis Workshop 2008 5
Model Development, Continued
Contactors were used to connect the longeron-inner facesheets & shoulder-backshell elements.
Longeron-facesheet & aft bulkhead flanges:G = 52.7 W/K
Shoulder-backshell (facesheets):G = 0.005 W/K
Inner facesheets
MD longeron flanges
Longeron-facesheet contact
Aft bulkhead flanges
Thermal & Fluids Analysis Workshop 2008 6
Model Development, Continued
Pressure Vessel (PV) Air Nodes
5 air nodes inside pressure vessel.No coupling between air nodes.
Estimated unoccupied volumes:
Main: 10.43 m3
Port: 0.55 m3
Stbd: 0.55 m3
Center: 1.2 m3
Under Crew Stowage: 1.46 m3
Total PV volume: 20.32 m3
Main Cabin Air Node
Air Node Under Crew Stowage
Air Nodes Behind ECLSS Wall
Thermal & Fluids Analysis Workshop 2008 7
Model Development, Continued
Power dissipationPre-landing: 2408.5 WPost-landing: 1149.3 W
Air node coupling to PV structure and inner components.
PV main node connection (left picture)Remaining nodes (right picture)No direct coupling between nodes.
Thermal & Fluids Analysis Workshop 2008 8
Model Development, Continued
BS & HS descent & landing conductors
No Fwd Bay cover during descent.Analysis does not include convection in the Fwd Bay during descent phase.Logic block used to obtain Heat Transfer Coefficients (HTCS) using corresponding correlations.
Post-landing
DescentAssumptions: Flat plate (BS) /Sphere (HS)
4.0325.0,
43.08.0,
PrRe*06.0Re*4.02
Pr*Re*029.0
DDHSD
LBSL
Nu
Nu94169
41
,
916169
121841,
Pr469.0
1
589.02
Pr
492.01
10*6.1167.068.0
DHSD
LLBSL
RaNu
RaRaNu
Thermal & Fluids Analysis Workshop 2008 9
Analysis Cases
5 phase analysis1. Lunar Transit: Steady state solution
Service Module attached, aft sun attitude2. Pre-entry orbit: 0-1884 sec.
120 km LEO with HS on the velocity vector3. Entry: 1884-3284 sec.
Heating stopped after 1400 secMain air node changed to diffusion node.
4. Descent: 3284-3667 sec.Convective cooling applied to HS and BS.FWD Bay cover removed.DSNE used for Solar flux and Sky temps
5. Post-landing: 3667-14784 sec (3hrs post landing)Natural convection used.
Parametric run of 20 cases done with different environment temperatures (Air and Sea temperatures)
Thermal & Fluids Analysis Workshop 2008 10
Analysis Cases, Continued
Reentry phase was based on a long lunar return, skip entry trajectoryHighest total heat load of lunar and ISS cases.Nominal aerothermal heating used includes a 1.1 factor for trajectory dispersion
DAC1 Long Lunar Skip Trajectory
0
50000
100000
150000
200000
250000
300000
350000
400000
450000
500000
0 500 1000 1500
Time (s)
Alt
itu
de
(ft)
0
5000
10000
15000
20000
25000
30000
35000
40000
Vel
oci
ty (
ft/s
)
Altitude (ft)
Velocity (ft/s)
DAC1 Long Lunar Skip Trajectory
0
50000
100000
150000
200000
250000
300000
350000
400000
450000
500000
0 10000 20000 30000 40000
Velocity (ft/s)
Alt
itu
de
(ft)
Thermal & Fluids Analysis Workshop 2008 11
Analysis Cases, Continued
52 body points chosen based on heating rate distribution
Body Point 21
0
100
200
300
400
500
0 500 1000 1500Time (s)
Hea
t Rat
e (B
tu/ft
2-s) Convective
Radiative
Body Point 232
0
0.5
1
1.5
2
2.5
3
0 500 1000 1500
Time (s)
Hea
t R
ate
(Btu
/ft2
-s) Convective
Radiative
Heating varies significantly over the heatshield surface
Thermal & Fluids Analysis Workshop 2008 12
Cabin Air Temperature Results
Results showed that the cabin air temperature was not sensitive to the environment temperatures analyzed (sea and air temperatures)
43.343.342.842.229.4
43.943.342.842.232.2
43.343.342.842.226.7
43.343.342.842.223.9
43.342.842.842.221.1Sea T
emperature
(C
)
35.032.229.426.7
Air Temperature ( C)
Cabin Main Air Node Temperatures
Thermal & Fluids Analysis Workshop 2008 13
Cabin Air Temp ResultsAir Temp = 35 C, Water Temp = 32.2 C
15
20
25
30
35
40
45
50
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0Time (hrs)
TRANSIT/PREENTRY ENTRY DESCENT LANDING
30 min orbit
23 min entry
6 min descent
Cabin air temperature peaks ~2.25 hrs after
landing
3 hr post-landing
Thermal & Fluids Analysis Workshop 2008 14
Effect of Heat Transfer Coefficienton Cabin Air Temperature
15
25
35
45
55
65
75
85
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Time (hrs)
No Convection Case19 SolutionNo Heat Shield Convection No Backshell ConvectionNo Heat Shield Convection During Descent No Backshell Convection During Descent
30 min
23 min entry
6 min descent
3 hr post-landing
Thermal & Fluids Analysis Workshop 2008 15
Conclusions
The main cabin node was not sensitive to the air and sea temperature ranges used as environmental boundaries for convective heat transfer.For all cases analyzed, the cabin air temperature reached approximately 43.9 C within 2.5 hours of landing.Convective heat transfer from the backshell during descent and post-land and from the heatshield during the descent has no significant effect on the cabin air temperatureThe heat transfer from the heatshield to the water is critical in removing thermal energy that might otherwise soak back into the vehicle s interior.
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