SAMPE Journal - March/April 2024 - 35

Figure 26 shows a representative encapsulated
OTB sample for microscopy test[1]
. Figure 27 shows
cross-section of CF/UHTR OTB samples: (a) before
OTB test; (b) ablation parameter (AP)=30 (kJ/cm2
(c) AP=60 (kJ/cm2
); and (d) AP=90 (kJ/cm2
)[1]
);
. AP
(ablation parameter) is the heating load defined as
the product of heat flux X exposure time.
The high X-ray flux of synchrotrons coupled with
fast detectors enables 3D micron-scale imaging
during in situ experiments that evolve on the
second time scale. Beamline 8.3.2 of the Advanced
Light Source at Lawrence Berkeley National
Laboratory is focused especially on imaging of
flow and fracture in geological samples as well as
mechanical testing of materials at ambient and
high temperatures. Beamline 8.3.2 was used to
perform micro-CT of various fiber preforms used
in ablative composites, as well as virgin ablator
samples, and char ablator samples evolved during
oxyacetylene test bed experiments[29-31]
. Pyrolysis,
mechanical properties at room temperature, and
mechanical properties at elevated temperature (up
to 1,500°C) are planned.
Object Research Systems (ORS) Dragonfly
software is a 3D visualization and analysis program
for use in tomography and other scientific composite
imagining techniques. Image slices processed by
Perlmutter at UC Berkeley are then composited in
Fiji/ImageJ and Dragonfly to render 3D images and
XZ/YZ plane slices. Deep Learning can be used for
analysis and automatic segmentation of samples.
Dragonfly can also be used to produce animations
for easier communication of complex internal
morphology.
Figure 28 shows the 3D rendering of micro-CT
images of virgin MX-360 (glass/phenolic) and char
MXB-360[29]
. Figure 29 shows 3D micro-CT images
of high-density quartz felt (left) and char quartz/
UHTR ablator (right).
The thermal conductivity of VDG Graphite/
UHTR virgin and char was calculated
NASA's Porous Microstructure Analysis (PuMA)
software[32,33]
Figure 24. Brief description of NASA LRC's HYMETS facility[27]
.
Figure 25. SEM images of virgin PICA (left) and char PICA (right).
using
. Using the deep learning segmentation
model, thermal conductivity values were entered
for each material. These images (Figure 30) show
PuMA's calculations for x-, y-, and z- applied heat.
The thermal conductivity of Graphite/UHTR
virgin and char was calculated using NASA's
Porous Microstructure Analysis (PuMA) software.
Using the deep learning segmentation model,
thermal conductivity values were entered for each
material. The magnitude of results is reasonable
although PuMA negative values are currently not
understood. Char materials have lower thermal
conductivity for both methods (Figure 31 and Table
3)[31]
. The comparison will be investigated further
in the future.
Figure 26. Representative encapsulated OTB sample for microscopy test[1]
VI. NUMERICAL MODELING
KRG uses the following software for our TPS
materials R&D:
* Flow field simulations using FLUENT and
LAURA codes.
* ACE[34-35], MULTATION++[36], Chemics[37]
1dFIAT[38]
, CMA92[39]
, ITRAC[40]
,
, and 3D
CHAR [41] material response simulations of
oxy-acetylene test bed (OTB) data.
The KRG team uses FLUENT code for flow field
simulations. Combustion modeling using Fluent
from Atak et al.[42]
www. sampe.org
MARCH APRIL 2024
|
OTB CFD work provided recovery
SAMPE JOURNAL |
35
.
http://www.sampe.org
SAMPE Journal - March/April 2024

Table of Contents for the Digital Edition of SAMPE Journal - March/April 2024
