Light Weight Ablator Response Model Development & Challenges

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Light Weight Ablator Response Model Development & Challenges

N. N. Mansour NASA Ames Research Center

Ablator Response model validated from fundamental experiment to flight data

Inauguration of the École Centrale Plasma Torch Nov. 17, 2014

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Needs for Thermal Protection Systems (TPS)


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TPS Systems

Two type of TPS materials


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NASA - Space Exploration

Current thinking •  Low Earth Orbits (LEO) – Private providers •  Beyond LEO – Both Private & NASA providers

Ø Ablators will play a major role in NASA’s atmospheric entry missions


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Widely used class of materials ü  Stardust ü  MSL ü  Dragon ü  AQ61 ü  …

Mars Science Laboratory (MSL) heatshield

Dragon capsule, SpaceX

Phenolic Impregnated Carbon Ablator (PICA)

Carbon-Phenolic class of ablators PICA: member of the family of Lightweight Carbon

Ablators (LCAs) that was developed at NASA Ames Research Center as a lightweight thermal protection system (TPS) material for the Stardust mission

= +

Excellent Performance: [250 W/cm2 to 1100 W/cm2]

carbon Fiberform™ resin


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Flight data: MEDLI


Mahzari et al. AIAA 2013-0185

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Performance of Current State Of the Art

Mahzari et al. AIAA 2013-0185 Inauguration of the École Centrale Plasma Torch Nov. 17, 2014

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Performance of Current State Of the Art

Mahzari et al. AIAA 2013-0185


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Flight data: MEDLI

Mahzari et al. AIAA 2013-0185 Inauguration of the École Centrale Plasma Torch Nov. 17, 2014

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Historical standpoint (1968)


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. Context Today’s standpoint (2008)

Have we reached the limita/ons of Kendall’s model (used in current codes)?


12/32 Chart from Rich Young, NASA ARC ⇒  Final shape reconstructed using data from 10 ablation sensors in heatshield Inauguration of the École Centrale Plasma Torch Nov. 17, 2014

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Need: understand then build phenomenological models

•  Improve global understanding

•  Determine the important phenomena

•  Derive phenomenological models

•  Validate

•  3D design (gap, holes, etc.)

•  Couple to environment

à  Revisit the physics

à  Analysis of the orders of magnitude

à  Multiscale approach (micro-to-macro)

à  Experiments on laboratory material

à  Development of 3D simulation tool

à  Development of coupling tools (multi-physics)

Methods

Keep the study as general as possible, but the physics changes from one material to another, and from one atmospheric re-entry to another.

Steps


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Type 1 model

Physics and Chemistry in Ablative Materials

1 - Virgin PICA

SEM micrographs (1)

1

3 - Charred PICA

3

2 - Partially charred 2

4 - Partially ablated

4

Stardust, Jan. 15, 2006

Imag

e cr

edit:

NA

SA

[1] M. Stackpoole et al., Post-Flight Evaluation of Stardust Sample Return Capsule Forebody Heatshield Material, AIAA 2008-1202

(1)

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Towards “High-Fidelity Model” •  Type 1: Heat transfer, pyrolysis, simplified transport of the pyrolysis gases, equilibrium chemistry, surface ablation (current state-of-the-art) •  Type 2: Type 1 augmented with an averaged momentum equation for the transport of the pyrolysis gases

•  Type 3: High-fidelity model (Type 2 + finite-rate chemistry, multi-component diffusion, in-depth ablation/coking, explicit radiative transfer model, …)


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Phenomenology

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C6 + 3 H2

3 C2H2

C (s)

2 O

O2

2 C (s) + O2 ! 2 CO

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Building a model for PICA class

(1)

[1] M. Stackpoole et al., Post-Flight Evaluation of Stardust Sample Return Capsule Forebody Heatshield Material, AIAA 2008-1202

1. Pyrolysis experiments and

modeling (TGA + mass spec/Flash hea/ng)

2. Abla/on experiments and

modeling (Side arm reactor/etc.)

3. Pyrolysis-‐abla/on coupling

(ICP tes/ng) 4. Flow Env. Material Res. Coupling

(Flight data/ICP tes/ng)


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Pyrolysis experiments & modeling

Reactor Condensor


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Detailed model of the pyrolysis


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PATO validation study

Adding water effects reproduces the observed hump in the MEDLI data Nov. 17, 2014 Inauguration of the École Centrale Plasma Torch

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Virgin material

Pyrolysis zone

Abla/on zone

≈ 400 K

≈ 1200 K

≈ 1400 K Coking zone

≈ 3000 K

OH

Phenolic polymer

H2 +

C6H6 + H2O

C6 + 3 H2

3 C2H2

C (s)

2 O

O2

2 C (s) + O2 2 CO

Boundary layer

Non-‐viscous flow

coking

rad.

Heat

≈ 6000 K

Stardust

TPS core

Macro illustra?on

[Lachaud et al., JSR, 47 (2010), 910-‐921]

[Stackpoole et al., AIAA 2008-‐1202]

Micro-‐scale simula?on of carbon/phenolic

abla?on

Spallation

High-fidelity modeling

Nov. 17, 2014 Inauguration of the École Centrale Plasma Torch

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HYMETS testing for spallation

Dual-‐exposure camera s/ll frames during FiberForm tes/ng in the HYMETS arcjet. Images are combined from several frames (Credit: Jennifer Inman and Steve Jones).

Term in FIAT is added to the Bc’ to account for spallation

Both Fiberform and PICA have been tested


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Tomography

X-ray Rotation stage

Camera


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Tomography


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Porous Media Analysis (PuMA) tool


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Exact solution for an oxidizing fiber


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PuMA verification


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Comparison to analytical solution


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PuMA


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DPLR/Ablator Response Model coupling

DPLR and Material response model: –  Communication between the two codes –  Parallelization strategy

Hunter negotiates between: •  DPLR •  Material response •  Grid generation

Hunter/LibMesh

CFD ARM


Time dependent energy soak into a simplified capsule structure for the MPCV.

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Summary

•  Material performance tests (ICP, ArcJets, Flight data, etc.) as well as basic laboratory testing campaigns are needed to advance material response models to match advancements in our ability to model the flow physics (i.e. the environment).


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Team + Collaborators

•  J. Lachaud •  F. Panerai •  A. Martin •  T. Magin •  I. Cozmuta •  J. Scoggins •  J-M. Bouilly •  S. Sepka •  D. Parkinson •  A. MacDowell •  A. Haboub •  H-W. Wong •  J. Peck •  R. Jaffe

•  Y. Dubief •  R. Cocker •  A. Amar •  G. Palmer •  Y-K. Chen •  M. Barnhardt •  S. Muppidi •  B. Kirk •  C. Henze •  A. Omidy •  J. Ferguson •  A. Wray


Light Weight Ablator Response Model Development & Challenges

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