Scientific and Technical Aerospace Reports Volume 38 July 28, 2000

methods are investigated for modeling the SGS standard deviation: Smagorinsky, gradient and scale-similarity. When properly
calibrated, the gradient and scale-similarity methods give results in excellent agreement with the DNS.
Author
Models; Scale (Ratio); Computational Grids; Direct Numerical Simulation; Evaporation; Interpolation; Lagrangian Function;
Mixing Layers (Fluids)
20000062308 NASA Glenn Research Center, Cleveland, OH USA
Numerical Simulation of Non-Rotating and Rotating Coolant Channel Flow Fields, Part 1
Rigby, David L., NASA Glenn Research Center, USA; [2000]; 26p; In English; No Copyright; Avail: CASI; A03, Hardcopy; A01,
Microfiche
Future generations of ultra high bypass-ratio jet engines will require far higher pressure ratios and operating temperatures
than those of current engines. For the foreseeable future, engine materials will not be able to withstand the high temperatures without
some form of cooling. In particular the turbine blades, which are under high thermal as well as mechanical loads, must be
cooled. Cooling of turbine blades is achieved by bleeding air from the compressor stage of the engine through complicated internal
passages in the turbine blades (internal cooling, including jet-impingement cooling) and by bleeding small amounts of air into
the boundary layer of the external flow through small discrete holes on the surface of the blade (film cooling and transpiration
cooling). The cooling must be done using a minimum amount of air or any increases in efficiency gained through higher operating
temperature will be lost due to added load on the compressor stage. Turbine cooling schemes have traditionally been based on
extensive empirical data bases, quasi-one-dimensional computational fluid dynamics (CFD) analysis, and trial and error. With
improved capabilities of CFD, these traditional methods can be augmented by full three-dimensional simulations of the coolant
flow to predict in detail the heat transfer and metal temperatures. Several aspects of turbine coolant flows make such application
of CFD difficult, thus a highly effective CFD methodology must be used. First, high resolution of the flow field is required to attain
the needed accuracy for heat transfer predictions, making highly efficient flow solvers essential for such computations. Second,
the geometries of the flow passages are complicated but must be modeled accurately in order to capture all important details of
the flow. This makes grid generation and grid quality important issues. Finally, since coolant flows are turbulent and separated
the effects of turbulence must be modeled with a low Reynolds number turbulence model to accurately predict details of heat transfer.
Derived from text
Flow Distribution; Rotation; Coolants; Cooling; Jet Engines; Three Dimensional Models
20000062852 Technische Univ., Faculty of Mathematical Sciences, Twente, Netherlands
Accurate Boundary-Element Method for Stokes Flow in Partially Covered Cavities
Driesen, C. H.; Kuerten, J. G. M.; May 1998; 44p; In English
Report No.(s): PB2000-104912; MEMO-1442; No Copyright; Avail: CASI; A03, Hardcopy; A01, Microfiche
The two-dimensional flow of a viscous fluid over an etched hole is computed with a boundary-element method. The etch-hole
geometry contains sharp corners at which the solution of the traction boundary-integral equation is singular. Therefore, only the
regular part of the solution is computed with the boundary-element method, using a singularity-subtraction method, and the singular
part of the solution is added. However, there are regions in which these regular and singular parts are of almost equal magnitude,
but different in sign. to avoid the subtraction and addition of large quantities where quantities of smaller order are computed a
domain-decomposition technique is introduced. The authors show that the accuracy indeed increases by the described techniques.
After extrapolation the results for a rectangular geometry agree very well with results obtained earlier with a semi-analytical
method.
NTIS
Boundary Element Method; Boundary Integral Method; Two Dimensional Flow; Steady Flow; Stokes Flow; Viscous Fluids
20000062853 NASA Glenn Research Center, Cleveland, OH USA
A Compact Dual-Crystal Modulated Birefringence-Measurement System for Microgravity Applications
Mackey, Jeffrey R., NASA Glenn Research Center, USA; Das, Kamal K., NASA Glenn Research Center, USA; Anna, Shelley
L., Massachusetts Inst. of Tech., USA; McKinley, Gareth H., Massachusetts Inst. of Tech., USA; Measurement Science and
Technology; 1999; ISSN 0957-0233; Volume 10, pp. 946-955; In English; Sponsored in part by Fannie and John Hertz Foundation
Contract(s)/Grant(s): NCC3-610; RTOP 101-33-00; Copyright; Avail: Issuing Activity
A compact modulated birefringence-measurement system has been developed for use in microgravity fluid physics applications
with non-Newtonian fluids such as polymer solutions. This instrument uses a dual-crystal transverse electro-optical modulator
capable of modulation frequencies in excess of 100 MHz. The two crystals are modulated 180 deg. out of phase from each
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