An ultra-fast, oct-tree
accelerated Monte-Carlo ray tracing algorithm is used by RadCAD
to compute radiation exchange factors and view factors. Innovations
by C&R Technologies to the ray tracing process have resulted
in an extremely efficient radiation analyzer. A unique progressive
radiosity algorithm has also been incorporated to compute radiation
exchange factors from view factor data. RadCAD has also incorporated
the progressive radiosity algorithm into heating rate calculations,
resulting in even faster performance. Automatic compression and
decompression of internal database files minimizes disk usage.
RadCAD uses Monte Carlo Ray Tracing to calculate
form factors, radiation conductors, and heating rates for true conic
surface representations for input into SINDA/FLUINT.
RadCAD is the first radiation analyzer to integrate arbitrary CAD
generated surfaces with familiar parameter-based (TRASYS like) surfaces.
of the many powerful concepts in RadCAD is that of a radiation analysis
group. Any surface, along with active side designations, can be
listed any number of times in different analysis groups. When a
radiation computation (form factors, RADKs, or fluxes) is invoked,
it operates only on the currently active analysis group.
provides for speed savings and convenient manipulations of the model.
consider the simple model depicted here. The radiation on the inside
of the box could be assigned to analysis group "internal," while
the same surfaces (with different active sides) could be assigned
to the analysis group "external." This permits two faster analyses
to be performed, rather than solving the combined case or having
to maintain two separate models.
groups have other uses as well. For example, they enable the user
to maintain alternate cases and alternate components within the
same geometric model. They are also one of the bases for creating
selection sets for model verification and for post processing.
Articulators are modeling objects that can be used to change the position or model geometry. Thermal Desktop has two types of articulators: assemblies and trackers. Assemblies can translate and rotate modeling objects (including other articulators) or groups of modeling objects. The translation and rotation of an assembly is user defined, but can be defined using complex mathematical expressions. Trackers are a special type of articulator that rotates model objects based on relative position, perhaps relative to the Sun or a star. Trackers are useful for pointing solar arrays, thermal radiators, etc. Trackers have a single degree of freedom, but can be nested within other trackers and/or assemblies for unlimited degrees of freedom.
Databases and Aliases
optical properties (solar absorptivity, infrared emissivity, degree
of specularity, etc.) can be input as numbers, or indirectly as
user-defined names ("white paint," "aft canister," etc.). These
names can refer to a property identified in a user-controlled database,
or they can refer to an alias. Property aliases enable the user
to reassign coatings or materials at a high level with little work.
For example, using the alias manager as shown here, the user can
reassign the optical properties of all components designated "radiator"
to be "white paint."
with an ability to quickly swap databases (i.e., to change the definition
of "white paint" with alternate white paints), aliases provide the
user with a quick means of performing what-if analyses, comparing
designs, events, and levels of degradation.
Thermal Desktop innovation is a tree-style manager for handling
the optional correspondence (mapping) between Thermal Desktop surfaces
and SINDA nodes. (Correspondence data may be used to collect predictions
for one or more nodes together before being output for SINDA.) This
intuitive form (as shown here) provides fast visual access to this
data, which is difficult to maintain in older analyzers.
is also automatically maintained when postprocessing SINDA results
on the Thermal Desktop drawing (an example of which is shown on
the first page).
allows users to accumulate accuracy by choosing to extend a ray
tracing analysis farther after having viewed intermediate results.
Previous RADK or heating rate solutions may be continued for added
accuracy without losing prior answers. The code automatically checks
to make sure that no changes have been made that render the previous
analysis invalid as a starting point
aid to existing TRASYS users, Thermal Desktop can directly import/export
TRASYS geometry and property information (such as the model shown
here), retaining a knowledge of BCS organization on different layers,
and which can be used as selection sets to help a user better exploit
unique new Thermal Desktop features. Thermal Desktop can also import
NEVADA and TSS models.