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Dissertation Defense: Computational Fluid Dynamics Uncertainty Analysis for Payload Fairing Spacecraft Environmental Control SystemsSpacecraft thermal protection systems are at risk of being damaged due to airflow produced from
Environmental Control Systems. There are inherent uncertainties and errors associated with using Computational Fluid
Dynamics to predict the airflow field around a spacecraft from the Environmental Control System. This paper describes
an approach to quantify the uncertainty in using Computational Fluid Dynamics to predict airflow speeds around an
encapsulated spacecraft without the use of test data. Quantifying the uncertainty in analytical predictions is imperative to
the success of any simulation-based product. The method could provide an alternative to traditional validation by test only
mentality. This method could be extended to other disciplines and has potential to provide uncertainty for any numerical
simulation, thus lowering the cost of performing these verifications while increasing the confidence in those
predictions.Spacecraft requirements can include a maximum airflow speed to protect delicate instruments during ground
processing. Computational Fluid Dynamics can be used to verify these requirements; however, the model must be
validated by test data. This research includes the following three objectives and methods. Objective one is develop,
model, and perform a Computational Fluid Dynamics analysis of three (3) generic, non-proprietary, environmental control
systems and spacecraft configurations. Several commercially available and open source solvers have the capability to
model the turbulent, highly three-dimensional, incompressible flow regime. The proposed method uses FLUENT,
STARCCM+, and OPENFOAM. Objective two is to perform an uncertainty analysis of the Computational Fluid Dynamics
model using the methodology found in Comprehensive Approach to Verification and Validation of Computational Fluid
Dynamics Simulations. This method requires three separate grids and solutions, which quantify the error bars around
Computational Fluid Dynamics predictions. The method accounts for all uncertainty terms from both numerical and input
variables. Objective three is to compile a table of uncertainty parameters that could be used to estimate the error in a
Computational Fluid Dynamics model of the Environmental Control System spacecraft system.Previous studies have
looked at the uncertainty in a Computational Fluid Dynamics model for a single output variable at a single point, for
example the re-attachment length of a backward facing step. For the flow regime being analyzed (turbulent,
three-dimensional, incompressible), the error at a single point can propagate into the solution both via flow physics and
numerical methods. Calculating the uncertainty in using Computational Fluid Dynamics to accurately predict airflow
speeds around encapsulated spacecraft in is imperative to the success of future missions.
Document ID
20140008550
Acquisition Source
Kennedy Space Center
Document Type
Thesis/Dissertation
Authors
Groves, Curtis Edward
(NASA Kennedy Space Center Cocoa Beach, FL United States)
Date Acquired
June 27, 2014
Publication Date
March 28, 2014
Subject Category
Fluid Mechanics And Thermodynamics
Report/Patent Number
KSC-E-DAA-TN13127
Funding Number(s)
WBS: WBS 725932.08.01.01.13
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Keywords
Fluid Dynamics
CFD
Heat Transfer
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