NASA Scientific and Technical Aerospace Reports

In high speed engines, thorough turbulent mixing of fuel and air is required to obtain high performance and high
efficiency. Thus, the ability to predict turbulent mixing is crucial in obtaining accurate numerical simulation of an engine and
its performance. Current state of the art in CFD simulation is to assume both turbulent Prandtl number and Schmidt numbers
to be constants. However, since the mixing of fuel and air is inversely proportional to the Schmidt number, a value of 0.45
for the Schmidt number will produce twice as much diffusion as that with a value of 0.9. Because of this, current CFD tools
and models have not been able to provide the needed guidance required for the efficient design of a scramjet engine. The goal
of this investigation is to develop the framework needed to calculate turbulent Prandtl and Schmidt numbers as part of the
solution. This requires four additional equations: two for the temperature variance and its dissipation rate and two for the
concentration variance and its dissipation rate. In the current investigation emphasis will be placed on studying mixing without
reactions. For such flows, variable Prandtl number does not play a major role in determining the flow. This, however, will have
to be addressed when combustion is present. The approach to be used is similar to that used to develop the k-zeta model. In
this approach, relevant equations are derived from the exact Navier-Stokes equations and each individual correlation is
modeled. This ensures that relevant physics is incorporated into the model equations. This task has been accomplished. The
final set of equations have no wall or damping functions. Moreover, they are tensorially consistent and Galilean invariant. The
derivation of the model equations is rather lengthy and thus will not be incorporated into this abstract, but will be included
in the final paper. As a preliminary to formulating the proposed model, the original k-zeta model with constant turbulent
Prandtl and Schmidt numbers is used to model the supersonic coaxial jet mixing experiments involving He, O2 and air.
Author (revised)
Supersonic Combustion Ramjet Engines; Turbulence Models; Prandtl Number; Schmidt Number
20040111376 NASA Glenn Research Center, Cleveland, OH, USA
Effect of Sizings on the Durability of High Temperature Polymer Composites
Allred, Ronald E.; Shin, E. Eugene; Inghram, Linda; McCorkle, Linda; Papadopoulos, Demetrios; Wheeler, Donald; Sutter,
James K.; [2003]; 10 pp.; In English; 14th International Conference on Composites, 14-18 Jul. 2003, San Diego, CA, USA
Contract(s)/Grant(s): 708-31-16
Report No.(s): Paper 1818; Copyright; Avail: CASI; A02, Hardcopy
To increase performance and durability of high-temperature composite for potential rocket engine components, it is
necessary to optimize wetting and interfacial bonding between high modulus carbon fibers and high-temperature polyimide
resins. Sizing commercially supplied on most carbon fiber are not compatible with polyimides. In this study, the chemistry of
sizing on two high modulus carbon fiber (M40J and M60J, Tiray) was characterized. A continuous desizling system that uses
an environmentally friendly chemical-mechanical process was developed for tow level fiber. Composites were fabricated with
fibers containing the manufacturer’s sizing, desized, and further treated with a reactive finish. Results of room-temperature
tests after thermal aging show that the reactive finish produces a higher strength and more durable interface compared to the
manufacturer’s sizing. When exposed to moisture blistering tests, however, the butter bonded composite displayed a tendency
to delaminate, presumably due to trapping of volatiles.
Author
Durability; High Temperature; Polyimides; Composite Materials; Temperature Effects
20040120891 Naval Air Warfare Center, China Lake, CA, USA
Uncontained Engine Debris Analysis Using the Uncontained Engine Debris Damage Assessment Model
Seng, S.; Manion, J.; Frankenberger, C.; Sep. 2004; In English
Report No.(s): PB2004-107306; No Copyright; Avail: National Technical Information Service (NTIS)
As part of the Federal Aviation Administration’s (FAA) Aircraft Catastrophic Failure Prevention Program, the Naval Air
Warfare Center was tasked to examine and evaluate the Uncontained Engine Debris Damage Assessment Model (UEDDAM).
UEDDAM was written to provide a standardized tool for uncontained engine rotor failure analysis. This study was conducted
to exercise the code and evaluate its usefulness in performing rotor burst analysis on a small generic business jet and a generic
twin-engine aircraft. This evaluation also supported the Aviation Rulemaking Advisory Committee, Power Plant Installation
Harmonization Working Group activities. This report explains the analysis methodology, results, and trade studies performed
using UEDDAM.
NTIS
Damage Assessment; Engine Failure; Failure Analysis; Prevention; Rotors
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