Techniques Employed by the NASA White Sands Test Facility to Ensure Oxygen System Component Safety

2009 ◽  
pp. 97-97-11 ◽  
Author(s):  
JS Stradling ◽  
DL Pippen ◽  
GW Frye
Keyword(s):  
Test Facility ◽  
System Component ◽  
Oxygen System ◽  
White Sands

White Sands Test Facility Test Stand 401

1998 ◽  
Author(s):  
David Harris ◽  
Robert Cort
Keyword(s):  
Test Stand ◽  
Test Facility ◽  
White Sands

The Behavior of Outgassed Materials in Thermal Vacuums

1988 ◽  
Vol 31 (5) ◽  
pp. 28-32
Author(s):  
William Mahone ◽  
Randy Kays
Keyword(s):  
Palmitic Acid ◽  
Surface Forces ◽  
Test Method ◽  
Test Facility ◽  
Aerospace Materials ◽  
Incident Flux ◽  
Dynamic Interactions ◽  
Evaporative Flux ◽  
White Sands ◽  
The Relationship

Scientists at the NASA White Sands Test Facility (WSTF) are investigating the relationship between outgassing and condensation for aerospace materials in space-like environments. The WSTF throughput test method was validated by previous testing at WSTF using palmitic acid. Data from these tests were compared with data from other preliminary tests by using adipic and behenic acids. The comparison indicates that surface forces between outgassed molecules and the condensing surfaces cause the condensation flux to be different from the incident flux. These forces can also cause the evaporative flux to be different from the expected value. These discrepancies are discussed in terms of both potential and dynamic interactions of outgassed molecules with surfaces. Although these surface forces are noticeable, their overall effect on the test is minimal.

Vacuum Baking of Shuttle/Centaur Components

1986 ◽  
Vol 29 (2) ◽  
pp. 46-48
Author(s):  
C. Weingartner
Keyword(s):  
High Performance ◽  
Space Shuttle ◽  
Material Selection ◽  
Test Facility ◽  
Organic Contamination ◽  
Upper Stage ◽  
General Dynamics ◽  
Materials Used ◽  
White Sands ◽  
Space Vacuum

A variation of the Centaur launch vehicle will be used as a high-performance upper stage to launch spacecraft from the Space Shuttle cargo bay into geosynchronous orbit. As an element of the Shuttle payload, Centaur must be designed to avoid contaminating sensitive spacecraft surfaces. Nonmetallic materials used in structural and electronic applications can exhibit high rates of outgassing in a space vacuum and contaminate critical spacecraft surfaces of varying temperatures as condensation occurs. Judicious material selection, per NASA specifications, is used to control instances of such contamination. Vacuum baking is permitted by NASA Specification SP-R-0022 to "bake out" potential sources of organic contamination. Most Shuttle/Centaur missions are planned for spacecraft having surfaces of various temperatures in locations that are susceptible to condensation of organic outgassing products. To determine the extent of potential contamination, General Dynamics has initiated a test program with the White Sands Test Facility that is designed to measure outgassing and condensation rates of nonmetallic components in their use configuration. This paper reviews the tests, equipment requirements, sensor instrumentation, and some of the results to date.

IMTHUA Methods for Thermal-Hydraulics Code Structure Uncertainty Assessment

2008 ◽  
Author(s):  
Mohammad Pourgol-Mohammad ◽  
Ali Mosleh ◽  
Mohammad Modarres
Keyword(s):  
Model Uncertainty ◽  
Uncertainty Assessment ◽  
Assessment Model ◽  
Test Facility ◽  
System Component ◽  
Thermal Hydraulics ◽  
Model Uncertainties ◽  
True Value ◽  
Code Structure ◽  
Model Mixing

A successful treatment of model uncertainty results in an expression of uncertainty that includes the true value at some stated level of confidence. Code structure uncertainties (model uncertainty) are a crucial source of uncertainty quantification for thermal-hydraulics (TH) system codes such as RELAP5, TRAC, and recently consolidated TRACE code. These codes are an assembly of models and correlations for simulation of physical phenomena and behavior of system component. In some cases there are alternative sub-models, or several different correlations for calculation of a single phenomenon of interest. There are also “user options” for choosing one of several models or correlations in performing a specific code computation. Dynamic characteristics of TH add more complexity to the code calculation, meaning for example, that specific code models and correlations invoked are sequence-dependent, and based certain (dynamic) conditions being satisfied. This paper discusses the techniques developed in the Integrated Methodology for Thermal-Hydraulics Uncertainty Analysis (IMTHUA), specifically for the treatment of uncertainties due to code structure and models. The methodology comprehensively covers various aspects of complex code uncertainty assessments for important accident transients. It considers the TH code structural uncertainties explicitly by treating internal sub-model uncertainties, and by propagating such model uncertainties in the code calculations (including uncertainties about input parameters.) Structural uncertainty assessment (model uncertainty) for a single model will be discussed by considering “correction factor”, “bias”, and also through sub-model output updating with available experimental evidence. In case of multiple alternative models, techniques of dynamic model switching, user controlled model selection, model mixing, and model maximization/minimization will be discussed. Examples from different applications including, Marviken test facility blowdown, LOFT LBLOCA and a typical PWR LOCA scenario calculations will be provided for greater clarification of the proposed techniques.

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