Flexible Thermal Protection Systems Trade Studies for HIAD Earth Atmospheric Reentry

Test Vehicle

Joseph A. Del Corso, John A. Dec, Alireza Mazaheri, Aaron D. Olds, Nathaniel J. Mesick, Walter E. Bruce III, Stephen J.

Hughes, Henry S. Wright, F. McNeil Cheatwood

NASA Langley Research CenterJoseph.A.DelCorso@nasa.gov

10th International Planetary Probe Workshop17-20 June 2013, San Jose

HIAD Earth Atmospheric Reentry Test

HIAD Overview

RoboticMissions

EarthReturn

DoD Applications

Tech Development & Risk Reduction

Flexible TPS (F-TPS) Development and

Qualification

Sub-Orbital Flight Testing

System Demonstration

F-TPS advances (combination of ground and flight testing) readies technology for mission infusion

Inflatable Re-entry Vehicle Experiments

HIAD Earth AtmosphericRe-entry Test

(HEART)

20132012

Mission Infusion

IRVE-II

IRVE-3

2

F-TPS is modular in that it utilizes different materials for each function

– Outer high temperature fabric– Insulation– Impermeable gas barrier

F-TPS Background

3

The HEART HIAD is a proposed secondary payload on the Orbital Sciences Cygnus spacecraft.

• Enhanced Antares launch vehicle, but paired with a Standard Pressurized Cargo Module (change to CRS contract)

• ISS utilization and mission implementation via the Cargo Resupply Services (CRS) contract require very early mission definition, interface development, and planning.

HEART Mission Goal• Develop and demonstrate a relevant-scale HIAD system in an

operational environment.

HEART Mission Objectives1. Demonstrate manufacturing processes of a large-scale

HIAD.

2. Demonstrate successful operation of a large-scale HIAD throughout the planned operational environments.

3. Validate HIAD predictive tools (structural, thermal, flight dynamics).

4

The HEART Concept

HEART Dramatically Increases HIAD Scale, Entry Mass and Entry

Environment Capabilities

HEART8 to 10 m Diameter

IRVE-33 m Diameter

Capability IRVE-II IRVE-3 HEART

HIADDiameter (m) 3 3 8 to 10

EntryMass (kg) 125 300 5500

Peak HeatRate (W/cm2) 2 15 30 to 50

Total HeatLoad (kJ/cm2) 0.02 0.2 5.0

5

HEART Launch-to-Flight Configurations

Stowed HEART HIADModule (LaRC)

InterstageStructure

(Orbital Sciences)Interstage to PCM Separation Plane

(Orbital Sciences)

Pressurized Cargo Module (PCM, Orbital Sciences)

Antares to Cygnus Separation Plane

(Orbital Sciences)

LaunchConfiguration

CygnusService Module

(Orbital Sciences)

CruiseConfiguration(to and from ISS)

Enhanced Antares Fairing

(Orbital Sciences)

ReentryConfiguration

Inflatable Structure(LaRC)

Flexible Thermal Protection System

(LaRC)

OML Trade Study Background

• Baseline HEART OML is 55-deg cone with non-spherical nose• Aerothermal analyses indicate peak heat rate (and resultant surface temperature)

could exceed current understood limit of the baseline F-TPS outer layer, and place more demands of the insulative layer.

• Options: change OML (cone diameter, cone angle, nose radius, shoulder radius), switch to advanced (Gen2) F-TPS materials, or reduce entry mass

6

HEART OML Configurations Matrix

• Additional length available with the Cygnus spacecraft allows spherical nose--function of vehicle diameter (D)

• 20 OML configurations initially considered

• 7-m configuration quickly eliminated due to excessive heating, flow impingement and aero stability concerns

Cone Angle (deg)

Nose Radius (m)D = 7 m D = 8 m D = 9 m D = 10 m

55 -- -- D/5 D/5.660 D/3.5 D/4 D/4.4 D/4.965 D/3 & D/4 D/3.4 & D/4 D/4 D/4.370 D/3 & D/4 D/3 & D/4 D/3.5 & D/4 D/3.5 & D/4

55 (baseline) -- Ellipsoidal-ish -- --

7

OML Trade Study Re-entry Trajectories

• POST2 3 degree-of-freedom simulation• 5500 kg entry vehicle

– 55 to 70 deg cone half angle– 8 to 10 m diameter

• Ballistic entry (0° angle of attack)• Newtonian drag coefficients• Deorbit from 421x180 km orbit

– 50 km perigee target

8

Aerothermal Analysis

• Langley Aerothermodynamic Upwind Relaxation Algorithm (LAURA) CFD code utilized

• Only ballistic entry conditions considered (no lift).• Surface assumed fully-catalytic with the temperature-dependent

emissivity. Radiative equilibrium surface temperature assumed.• Solutions obtained for both laminar and fully-turbulent (Cebeci-Smith)

flows.• Radiative heating computations obtained with 11-species, 2-

temperature non-equilibrium air models. Only laminar flow was simulated for radiative heating estimation.

• Flight indicators (laminar and fully-turbulent) were generated for the solid nose cap and the inflatable portion of each configuration, and then implemented in POST2.

• For each flight heating indicator, corresponding arc-jet heater settings were defined based on the computed flight-to-ground correlations

9

Surface Temperature Results

Max D (m)

Cone Angle (deg)

Nose Radius

Nose Heating (W/cm2)

NextelNose T(K)

SiCNose T(K)

IAD Heating(W/cm2)

NextelIAD T(K)

SiCIAD T(K)

8 60 D/4 64 2060 1669 61 1920 15558 65 D/3.5 61 2020 1636 57 1880 15238 65 D/4 67 2100 1701 56 1860 15078 70 D/3 54 1990 1612 46 1810 14668 70 D/4 62 2030 1644 45 1805 14629 55 D/5 64 2070 1677 52 1880 15239 60 D/4.4 60 2010 1628 49 1875 15199 65 D/4 56 2000 1620 43 1800 14589 70 D/3.5 50 1970 1596 37 1730 14019 70 D/4 53 1970 1596 41 1770 1434

10 55 D/5.6 60 2030 1644 47 1820 147410 60 D/4.9 55 1990 1612 43 1800 145810 65 D/4.3 45 1970 1596 41 1770 143410 70 D/3.5 44 1850 1499 33 1660 134510 70 D/4 46 1900 1539 36 1740 14098.3

Baseline 55 --- 55 1990 1612 47 1805 1462

10

Approximate Temperature Limits: Nextel–1723K, SiC–2023K

• LCAT – Huels arc heater– 18” and 27” cathodes with secondary air

and 12” mixing section– Heat flux range 5-150 W/cm2

– Surface pressure range 1-9 kPa– Shear range 30-270 Pa– Reacting flow

Ground Testing at Large-Core Arc TunnelThe Boeing Company

• Facility Ground Testing– Test coupon samples at stagnation and

shearing conditions– Test at relevant mission profile heat flux

and pressure

11

Arc

Nominal Trajectory (Vehicle Stagnation Point)Profile Test Conditions

Initial Heating17 W/cm2 20 W/cm2 30 W/cm2 40 W/cm2

Peak Heating50 W/cm2

Side

Vie

w

Baseline F-TPS Sample Performance

Sting Arm 2 UnitsTest Condition (Nominal Cold Wall Profile) 50 (W/cm2)Measured Peak Heat Flux 50.5 (W/cm2)Test Duration (Full profile completed) 300 (sec)Time to 250°C (TC8K, post-profile exposure) 373 (sec)Max Temperature Reached (post exposure) 317 (°C)

Run PerformanceWeave appeared to be slightly more porous near the peak heating of the test, but was intact

Sting Arm 2

Pre-Test Post-Test

13

HEART BaselineNextel 440 BF-20

Pyrogel 2250KKL

Option A F-TPS Sample Performance

Sting Arm 1 Sting Arm 2 UnitsTest Condition (Nominal Cold Wall Profile) 50 50 (W/cm2)Measured Peak Heat Flux 53.1 53.1 (W/cm2)Test Duration (Full profile completed) 300 300 (sec)Time to 250°C (TC8K, post-profile exposure) 501 419 (sec)Max Temperature Reached (post exposure) 253 275 (°C)

Run Performance Well behaved and was tested for the entire duration.

Sting Arm 2

Post-Test

14

Post-Test

Sting Arm 1

Option A

SiCPyrogel 2250

KKL

Option B F-TPS Sample Performance

Sting Arm

1Sting Arm

2 UnitsTest Condition (Nominal Cold Wall Profile) 50 50 (W/cm2)Measured Peak Heat Flux 51.9 51.9 (W/cm2)Test Duration (Full profile completed) 300 300 (sec)Time to 250°C (TC8K, post-profile exposure) 329 326 (sec)Max Temperature Reached (post exposure) 371 378 (°C)

Run Performance Well behaved and was tested for the entire duration.

Sting Arm 1 Sting Arm 2

Post-Test Post-Test

15

Option B

Saffil 96Pyrogel 2250

KKL

SiC

Ongoing F-TPS Development within HIAD Project

– Advancing second generation materialsDeveloping advanced SiC weaving, and investigating manufacturing, and handle-ability

– FTPS investigating graphite and carbon felt insulators at LCAT• Material manufacturing processes are consistent and

repeatable• Materials have thermophysical characteristics similar to Saffil• Materials are mechanically viable for packing• Materials are similar to pyrogel in mechanical durability and

handling (carbon slightly more susceptible to shearing tearing loads) but no particulates

– Investments in third generation insulator developmentPolyimides (GRC), OFI (Miller Inc.), APA (GRC)

16

Conclusions

• Increased cone angle and nose radius offers the lowest peak heating solution for the aeroshell, however, structural stability concerns need to be addressed for cone angles greater than 60 deg.

• For HEART, the aeroshell diameter should be greater than 8 meters to minimize payload impingement, reduce forebody heat rates, and improve aero stability.

• Due to its relatively low emissivity, F-TPS configurations using the Nextel BF-20 fabric realize higher surface temperatures than experienced by SiC (which has a higher emissivity).

• F-TPS designs using Nextel BF-20 fabric may be possible for configurations with low peak heating. However, design margin may be unacceptable.

• F-TPS designs using SiC fabric are suitable for all HEART configurations considered in the study with an expectation of acceptable design margin.

• Arc-jet test results for HEART representative heating profiles verify that our selection for F-TPS materials will survive expected re-entry conditions at the design back-face temperature.

17