AIAA 2006-4605 Thermal Protection System Sizing and Selection … · 2016. 9. 27. · SpaceWorks...
Transcript of AIAA 2006-4605 Thermal Protection System Sizing and Selection … · 2016. 9. 27. · SpaceWorks...
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AIAA 2006-4605Thermal Protection System Sizing and Selection for RLVsUsing the Sentry CodeRevision A10 July 2006
John E. Bradford, PresidentJohn R. Olds, Technical Fellow
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Introduction to SpaceWorks Engineering, Inc. (SEI)
Overview:- Engineering services firm based in Atlanta (small business concern)- Founded in 2000 as a spin-off from the Georgia Institute of Technology- Averaged 130% growth in revenue each year since 2001 - 87% of SEI staff members hold degrees in engineering or science
Core Competencies:- Advanced Concept Synthesis for launch and in-space transportation systems- Financial engineering analysis for next-generation aerospace applications and markets- Technology impact analysis and quantitative technology portfolio optimization
MotivationTool OverviewSpace Shuttle Verification StudyTSTO MSP Case StudyConclusions and Future Work
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Presentation Overview
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Motivation
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Develop thermal protection system (TPS) analysis tool that will determine which materials should be used on a launch vehicle and determine how much these materials will weigh
Permit fully-coupled analyses with trajectory and vehicle weights/sizing disciplines in the conceptual/preliminary design phase
Have sufficient fidelity to provide results within +/- 15% of actual weight if constructed and provide sufficient detail to advance design to next stage of development
Tool needs to be fast, robust, and capable of functioning within an automated environment
Objective and Goal
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Design Structure Matrix: All-Rocket SSTO RLV
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Tool Overview
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Created by SpaceWorks Engineering, Inc. (SEI) to support vehicle design studies
Designed from onset to support automated and batch process execution
For use in conceptual and preliminary design of space transportation systems that utilize reusable, non-ablative TPS
Written in modern, object-oriented C++ programming language- Compiled for and executes on PC, Mac OS X, and SGI Unix
Execution time is from 5 to 45 minutes, depending upon setup, optimization level, and analysis resolution
User interface via command-line execution and ASCII input/output files or using Phoenix Integration’s ModelCenter© environment
Sentry: What is it?
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Perform a 1-D unsteady heat transfer analysis with convection, conduction, and radiative effects and an adiabatic backface condition
Consider an unlimited number of candidate TPS materials or “stackups” at each nodal location for a given vehicle geometry and grid
Determine the TPS requirements over the entire vehicle, including the windward and leeward airframe surfaces, chines, wing(s), tail(s), vertical stabilizer(s), and aerodynamic control surfaces
Over the entire vehicle, optimize the thickness of the stackup to minimize weight after factoring in the material properties, temperature limitations, and any manufacturing constraints
At vehicle leading edges, determine the stagnation point conditions using a representative geometry and select an appropriate material based on surface temperatures experienced
Sentry: What can it do?
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X
Material Layer #1
Material Layer #2
Material Layer #3
Material Layer #4
Material Layer #5
Material Layer #6
Backface or Bondline Surface
layer thickness
Exposed Surface
Definition of TPS Stackup
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Input Specifications‘General Parameters’ provided by user include:
Specification method for Qconv interpretation (Direct or Interpolation)Default panel multiplier valueAngle-of-attack override flagVehicle scale factor
‘Component Parameters’ provided by user include:
Initial temperature to initialize airframe components at start of analysisLeading edge specifications (geometric shape, radius, emissivity, etc.)Qconv margin to apply to stagnation and non-stagnation point values
‘Candidate Stackup Parameters' provided by user include:
Total number of candidate stackups defined for vehicle (typically 5-15)Vehicle component assignments for candidate stackupsNumber of material layers in each stackupMaximum height permitted for stackupSizing layer in stackup for optimizerBackface or bondline temperature requirement for stackupMaterial layer(s) ID number, min. gauge, max. surface temperature
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Output Data and ResultsSummary Output File
- Total TPS weight and average weight per unit area for entire vehicle- TPS weights and weight per unit area by component- Acreage material fractions by component (e.g. forebody is 25% CRI, 65% TUFI AETB-8, and 10% TUFI AETB-12)- Maximum stagnation and non-stagnation point temperatures encountered
Tecplot© formatted File
- Maximum surface temperature, material/stackup thicknesses (per layer and total), and material type over entire analysis grid
Detailed Grid/Node Data
- Surface temperature history vehicle time at use specified locations on vehicle- Temperature history into material stackup structure versus time (through the thickness temperature profile)
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Convective Heat Rate Generation
SEI-preferred method for obtaining convective heat rate data is via APAS’sSupersonic/Hypersonic Arbitrary Body Program (S/HABP)
Additionally, Sentry utilizes same analysis grid as that generated by APAS
Two methods used for data specification:1) Direct – Generate Qconv based on actual trajectory flight conditions2) Interpolated – Generate database of Qconv over flight envelope that encompasses the actual trajectory flight conditions
For automated execution of Sentry, the second method should be utilized
S/HABP data file provides x, y, z-coordinates at centroids of analysis grid, surface area for each grid node, and Qconv versus flight Mach number, altitude, and angle-of-attack (AOA)
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Database originated at NASA Ames Research Center from TPSXOriginally written in Fortran 77, converted to ‘C’ for improved integration with SentryIncludes property data for over 100 different TPS and structural materialsInteger ID number identifies desired material in databaseProperties include:
Density (ρ)Thermal Conductivity (k)Heat Capacity (Cp)
1-D (temperature) and 2-D (temperature and pressure) linear interpolation algorithms for property data
Material Property Database - TPSX
Reaction Cured Glass (RCG)Conformal Reusable Insulation (CRI)AETB-8, 12, 16, and 20
Common Materials from TPSX Database
Carbon/SiliconCarbide (C/SiC)
Cerachrome-8 and 12
Internal Multiscreen Insulation
Advanced Carbon Carbon (ACC)
LI-900 and LI-2200
Strain Isolation Pad (SIP)
Inconel-617Aluminum-2219
TitaniumSaffil
NextelRohacel Foam
TUFI (Coating and Diffusion Layer)Flexible Reusable Surface Insulation (FRSI)
Reusable Carbon Carbon (RCC)FRCI 12 and 20
RTV-560Advanced Flexible Reusable Surface Insulation (AFRSI)
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For a given TPS panel, solve 1-D unsteady, heat equation:
Fully implicit solver method using Newton-Rhapson iteration- Central finite differencing scheme at interior nodes (FTSS)- Forward/Backward differencing schemes at upper and lower surface nodes (FTFS)
Top tile surface accounts for conduction, convection, and radiation
Currently only has adiabatic backface boundary condition
Boundary Condition’s:
@ x=0
@ x=L
2
2
xT
tT
∂∂
=∂∂ α
04 =+−dxdTkTq sconv εσ
0=dxdT
Heat Transfer Analysis and Solver
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Verification Study
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Space Shuttle Orbiter Model in APAS
Original model provided by NASA Langley Research Center
SEI modifications included addition of cross sections and points to increase number of grid points
Wing was not reconstructed, although thickness of tip lead edge was identified as being less than actual shuttle LE radii (will impact LE temperature predictions)
Windows were ignored and TPS was sized in these areas
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0
5
10
15
20
25
30
0 200 400 600 800 1,000 1,200
Time (s)
100,000
125,000
150,000
175,000
200,000
225,000
250,000
275,000
300,000
0 200 400 600 800 1,000 1,200
Time (s)
Mach Number Altitude
Trajectory: Mach Number and Altitude vs. Time
• Shuttle Orbiter simulation conducted using POST trajectory code
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TPS Candidate Materials Specified to Sentry
RCC, LI-2200, LI-900, FRSIUpper Wing
RCC, LI-2200, LI-900, FRSITail
RCCWing and Vertical Leading Edges
RCC, LI-2200, LI-900Body Flap
RCC, LI-2200, LI-900, AFRSI, FRSIOMS/RCS Pods
RCC, LI-2200, LI-900
RCC, LI-2200, LI-900, AFRSI, FRSI
CANDIDATE MATERIALS
Lower Wing
Fuselage/Body
COMPONENT
LI-2200 and LI-900 minimum gauge thickness of 0.5 inchesAFRSI minimum gauge thickness of 0.41 inchesFRSI minimum gauge thickness of 0.14 inchesRCC assumed to be 0.5 inches thick with Cerachrome-8 backingFor all components, a backface temperature limit of 810 R was imposed
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Temperature (R)
LEEWARD
WINDWARD
FRONTSIDE
Space Shuttle Results – Maximum Surface Temperatures
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Sentry analysis required about 10 minutes of computational timeDifference in total TPS weight approximately 5%Most significant difference appeared on OMS/RCS pods (~50% error, or 600 lb.)Total TPS surface area difference was less than 1% (~100 ft2)
Weight (lb.)
Sentry AnalysisSpace Shuttle (Actual)**
17,910
806
1,167
800
8,443
6,693
17,114Total
734Body Flap
549OMS/RCS Pods
665Tail
8,517Wings
6,649Fuselage / Body
Space Shuttle Results – Component Weights
**Weights do not include gap fillers, bonds, joints, closeouts, thermal barriers, carrier strips, etc.
Still investigating the differences in TPS results for OMS/RCS podsDifference appears to be primarily in material thickness and not typeCurrent thoughts for explanation of differences:
- Shadowing of pods from S/HABP and thus reduced Qconv predictions in this area- Ascent profile could be driver for TPS sizing
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FRONTSIDE
LEEWARD
WINDWARD
Space Shuttle Results – TPS Material Distribution
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TSTO MSP Case Study
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Quicksat (Mated Configuration)
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Key Vehicle Technologies and Features
(6) TBCC engines(4) DMSJ engines with variable inletUHTC SHARP TPS leading edges (nose, cowl, wings, and tails)Gr-Ep Airframe primary and secondary structureCylindrical, non-integral Gr-Ep fuel tanks and Al oxidizer tanksCRI TPS blankets (fuselage, windward)AFRSI blankets (fuselage, leeward and sidewalls)EHA’s (electro-hydraulic actuators) for control surfacesNo OMS engine requirementIntegrated Vehicle Health Monitoring (IVHM) systemsAll-moving vertical tails
Cylindrical, non-integral Al propellant tanksAFRSI TPS blankets over unshielded upper surfaceMPS engine used as OMS engine for deorbit burnOMS deorbit delta-V of 100 ft/s
Closed-Cycle, JP-7/H2O2 rocket enginesPressure-fed, blow-down monopropellant (H2O2) RCSAdvanced avionics for autonomous flight capability
Quicksat Specific
Upperstage Stage Specific
Entire System
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Integrated Quicksat/Upperstage MSP 3-View
Upperstage Space Maneuver Vehicle (SMV)
52.2 ft
Gross Weight – system (lbs): 741,670
Dry Weight – Quicksat (lbs): 167,840
Dry Weight – Upperstage (lbs): 4,275
Mass Ratio – Quicksat: 2.418
Mixture Ratio – Quicksat: 0.390
Length (ft) 123.6
Booster Payload – Upperstage + SMV (lbs): 89,515
Space Maneuver Vehicle – SMV (lbs): 13,090
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0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
450,000
500,000
0 200 400 600 800 1,000 1,200 1,400 1,600
Time (s)
Alt
itu
de (
ft)
Staging Maneuver
Transonic Rocket Boost
Transition TBCC to DMSJ
0
5
10
15
20
25
30
0 200 400 600 800 1,000 1,200 1,400 1,600
Time (s)
Mach
Nu
mb
er
Staging Maneuver
Transonic Rocket Boost
Transition TBCC to DMSJ
Mach Number Altitude
Trajectory and Analysis Setup
Sentry Analysis Setup: • Simulation modeled flyout, pullup, and staging maneuver with 2 hour flyback/thermal soak period• Airframe aeroheating analysis started at Mach 1.25, with uniform structure temperature at 560 R• Constant surface emmissivity of 0.8 for all surface regions• Forebody cylindrical nose leading edge radii of 2” used for stagnation calculations• Wing control surfaces deflected upward 5o and downward 15o over entire flight profile for assessment• Constrained forebody to utilize rigid tiles to maintain smooth surface lines for inlet/engine flow
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Quicksat SOV and Sentry Analysis Grid
Vehicle analysis grid consisted of 2,048 individual nodes
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TPS Candidate Materials Specified to Sentry
2.52,860TUFI AETB-8
2.52,860TUFI AETB-12
0.25” + SAFFIL3,360ACC
0.25” + SAFFIL3,460C/SiC
0.25” + SAFFIL4,460UHTC
2.02,000CRI
0.75” + SAFFIL3,360ACC
0.75” + SAFFIL3,460C/SiC
0.5” + SAFFIL4,460UHTC
3.02,000CRI
0.25” + SAFFIL4,460UHTC
Maximum Allowable Height (in)Maximum Temperature (R)COMPONENT – Wing Control Surfaces
0.25” + SAFFIL3,360ACC
0.25” + SAFFIL3,460C/SiC
Maximum Allowable Height (in)Maximum Temperature (R)COMPONENT – Wings and Tails
2.51,660AFRSI
2,860
2,860
Maximum Temperature (R)
8.0
8.0
Maximum Allowable Height (in)
TUFI AETB-12
TUFI AETB-8
COMPONENT - FuselageTUFI tiles included diffusion layer, AETB-8, RTV-560s and SIP
UHTC, C/SiC, and ACC with titanium backface heat sink (not reflected in weight, part of main structure)
Airframe required backfacetemperature not to exceed 760 R
Wings and Tails backfacetemperatures allowed up to 950 R
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Quicksat Results - Maximum Surface Temperatures
LEEWARD
WINDWARD
Temperature (R)
FRONTSIDE
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Quicksat - TPS Material Weight Results
AVG. UNIT WEIGHT
MATERIAL STACKUPCOMPONENT - Tails
12.6 psfACCLeading Edges0.82 psfCRIWindward Side0.82 psfCRILeeward Side
AVG. UNIT WEIGHT
MATERIAL STACKUPCOMPONENT - Wings
12.6 psfACCLeading Edges1.37 psfCRIWindward Side0.82 psfCRILeeward Side
12.6 psfACCNose
TUFI AETB-8 Ceramic Tiles and CRI
AFRSI Blankets and CRI
MATERIAL STACKUP
1.47 psf0.75 psf
AVG. UNIT WEIGHT
Windward Forebody and Aftbody Nozzle
Leeward and Sidewalls
COMPONENT - Fuselage
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Quicksat ModelCenter© Closure Model with Sentry
Conclusions and Future WorkSpaceWorks Engineering, Inc. (SEI)
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Summary and Conclusions
SpaceWorks Engineering, Inc. (SEI) has developed a new engineering software tool for aeroheating analysis and TPS sizing. This tool has proven to be fast, robust, and capable of automated execution.
Results of the verification exercise showed good agreement between Sentry TPS weight and temperature predictions and actual data for the Space Shuttle Orbiter
- Region of greatest difference was OMS/RCS pods; Work continuing to better understand this effect
Sentry was successfully incorporated into a multidisciplinary design process and used in an automated fashion for the TPS design of a TSTO combined-cycle MSP concept
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Future Work
Options for future Sentry capabilities being considered and/or implemented include:
1) Ability to specify an isothermal instead of adiabatic backface condition- Permit heat transfer through airframe/tank wall- Less conservative approach, but may be warranted in some cases
2) Incorporate scale-factor output parameter that represents the impact to vehicle outer mold line due to TPS thicknesses
3) Expansion of TPSX property database to incorporate material cost and maintenance data
- Enable alternate optimization variable besides weight through use of Overall Evaluation Criteria
4) Allow for radiative heat transfer to occur on backface of stackup- Handle gap or standoff distance on backside
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www.sei.aero
Business Address:SpaceWorks Engineering, Inc. (SEI)1200 Ashwood ParkwaySuite 506Atlanta, GA 30338 U.S.A.
Phone: 770-379-8000Fax: 770-379-8001
Internet:WWW: www.sei.aeroE-mail: [email protected]