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Graphical
Model Builders for Spacecraft Thermal Design
This paper discusses the different technologies
used by graphical model builders for SINDA thermal models
along with their advantages and disadvantages. These
graphical model builders may be network based, or geometric
based which uses finite elements or shapes based on
primitives.
Performance
Testing of Thermal Interface Filler Materials in a Bolted
Aluminum Interface Under Thermal/Vacuum Conditions
A thermal interface material is one of
the many tools that are often used as part of the thermal
control scheme for space-based applications. These materials
are placed between, for example, an avionics box and
a cold plate, in order to improve the conduction heat
transfer so that proper temperatures can be maintained.
Historically at Marshall Space Flight Center, CHO-THERMÒ
1671 has primarily been used for applications where
an interface material was deemed necessary. However,
there have been numerous alternatives come on the market
in recent years. It was decided that a number of these
materials should be tested against each other to see
if there were better performing alternatives. The tests
were done strictly to compare the thermal performance
of the materials relative to each other under repeatable
conditions and they do not take into consideration other
design issues such as off-gassing, electrical conduction
or isolation, etc. This paper details the materials
tested, test apparatus, procedures, and results of these
tests.
Implementation
of a Water Flow Control System into the ISS's Planned
Fluids & Combustion Facility
The Fluids and Combustion Facility (FCF)
is planned to become an ISS facility capable of performing
basic combustion and fluids research. The facility consists
of two independent payload racks specifically configured
to support multiple experiments that will depend upon
the ISS’s Moderate Temperature Loop (MTL) for
removing waste heat generated by the avionics and experiments
operating within the racks. This paper describes the
method selected to satisfy the FCF design requirements
while maintaining the constraints applied by the ISS
vehicle.
Sensitivity
Equation Derivation for Transient Heat Transfer Problems
The analytical approaches used for sensitivity
analysis can be classified in various categories; the
discrete approach vs. the distributed (continuous) approach
or the direct differentiation approach vs. the adjoint
variable approach. The main focus of this report is
on the derivation of sensitivity equations for transient
heat transfer problems modeled by different discretization
processes. Two examples will be used in this study to
facilitate the discussion. The first example is a coupled,
linear transient heat transfer problem that simulates
the press molding process in fabrication of composite
laminates. The state equations compute the temperature
distribution in the resins due to heat conduction and
chemical-kinetic reaction. These state equations are
discretized into standard h-version finite elements
and solved by a multiple step, predictor-corrector scheme.
The sensitivity analysis results based upon the direct
and adjoint variable approaches will be presented. The
second example is a nonlinear transient heat transfer
problem solved by a p-version discontinuous Galerkin
Method. The resulting matrix equation of the state equation
is simply in the form of , representing a single step,
time marching scheme. A direct differentiation approach
will be used to compute the thermal sensitivities of
sample 2D problems.
Automating
the Search for Worst-Case Design Scenarios
This paper describes readily available
techniques for automating the search for worst-case
(e.g., "hot case", "cold case")
design scenarios using only modest computational resources.
These methods not only streamline a repetitive yet crucial
task, they usually produce better results. The problems
with prior approaches are summarized, then improvements
are demonstrated via a simplified example that is analyzed
using various approaches. Finally, areas for further
automation are outlined, including attacking the entire
design problem at a higher level.
Improved
Measurements of External Heat Rates on Launch Vehicles
Knowledge of aerothermally induced convective
heat transfer and plume induced radiative heat transfer
loads is essential to the design of thermal protection
systems for launch vehicles. Typically, Schmidt-Boelter
gauges, taking advantage of the 1-D Fourier’s
law, measure the incident heat flux. This instrumentation,
when surrounded by low-conductivity insulation, has
an exposed surface temperature significantly lower than
the insulation. As a result of this substantial disturbance
to the thermal boundary layer, the heat flux incident
on the gauge tends to be considerably higher (potentially
by factors of 2 or more) than it would have been on
the insulation had the calorimeter not been there. In
addition, the gauge can receive energy radially from
the hotter insulation, contributing to the increase
of the indicated heat flux. This paper will present
an overview of an effort to account for these effects
and improve the accuracy of such measurements. Model
calibration testing performed on flat plates exposed
to an aerothermal environment will also be discussed,
as will alternate heat flux measurement techniques.
Internal Flow
Thermal/Fluid Modeling of STS-107 Port Wing in Support
of the Columbia Accident Investigation Board
This paper details the generation of
a coupled thermal and venting math model of the Orbiter
port wing in support of the Columbia STS-107 accident
investigation. This bulk model was created in SINDA/FLUINT
with Thermal Desktop/FloCAD in order to provide mass
flowrate and pressure boundary conditions of the leading
edge and wing volume for detailed computational fluid
dynamics modeling performed by other teams supporting
the investigation. Chemical equilibrium air thermodynamic
properties of the high enthalpy breach air is included.
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