NASA Scientific and Technical Aerospace Reports
NASA Scientific and Technical Aerospace Reports
NASA Scientific and Technical Aerospace Reports
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place in practice the formulated flow control strategy will be extended to fully developed turbulent boundary layers. The<br />
investigations were carried out experimentally in wind tunnels <strong>and</strong> numerically <strong>and</strong> were focused on structural peculiarities<br />
of a near-wall flow <strong>and</strong> their connection with integral flow characteristics. Special attention was paid to modifications of the<br />
turbulence scale/spectra, dissipation rate of turbulence energy, influence on Reynolds shear stress <strong>and</strong> estimation/<br />
measurements of skin friction coefficients. Computational results were verified by measured values of integral boundary- layer<br />
characteristics for various cases of flow control.<br />
DTIC<br />
Boundary Layer Control; Embedding; Turbulent Flow; Vortices<br />
20040111477 Georgia Inst. of Tech., Atlanta, GA<br />
Development of Acoustic Based, Multi-tasking Sensing <strong>and</strong> Actuation Capabilities for Gas Turbines<br />
Lieuwen, Tim; Jun. 30, 2004; 19 pp.; In English; Original contains color illustrations<br />
Contract(s)/Grant(s): DAAD19-01-1-0571<br />
Report No.(s): AD-A425424; E-16-T70; ARO-41297.2-EG; No Copyright; Avail: CASI; A03, Hardcopy<br />
This program is developing acoustic techniques for non-intrusive sensing <strong>and</strong> actuation of gas flows. Controlling <strong>and</strong>/or<br />
monitoring the degree of mixing between constituents of a multi-component media is a key problem in a variety of<br />
applications. Monitoring such mixing processes necessarily requires capabilities for quantification of the level of ‘mixedness.’<br />
However, quantification of molecular mixedness levels, as opposed to macro-scale entrainment, is difficult. Under this<br />
program, we have demonstrated the use of acoustic absorption measurements to characterize an average level of molecular<br />
mixedness between gases across the wave propagation path. This report presents the results of example calculations <strong>and</strong><br />
experiments demonstrating the feasibility of this technique <strong>and</strong> the significant sensitivity of acoustic absorption levels upon<br />
gas mixedness; e.g., measurements reported here show acoustic amplitude differences of up to a factor of ten between identical<br />
gas mixtures whose only difference is the level of mixedness of their constituent gases.<br />
DTIC<br />
Detection; Gas Turbines; Sound Detecting <strong>and</strong> Ranging<br />
20040111702 Army Engineer Research <strong>and</strong> Development Center, Vicksburg, MS<br />
L<strong>and</strong>scaping Considerations for Urban Stream Restoration Projects<br />
Bailey, Pam; Fischenich, Craig; Apr. 2004; 11 pp.; In English<br />
Report No.(s): AD-A425858; ERDC-TN-EMRRP-SR-42; No Copyright; Avail: CASI; A03, Hardcopy<br />
Many restoration projects are implemented in urban environments, where the l<strong>and</strong>scape <strong>and</strong> environmental conditions<br />
have been sufficiently altered that true restoration aimed at achieving ‘natural’ functions is limited <strong>and</strong> the reconstruction of<br />
pre-impact form is impossible. Under these circumstances, <strong>and</strong> in many cases where such constraints do not exist, the success<br />
of a project as viewed by the public is often based largely on the visual appeal of the site after restoration <strong>and</strong> its functionality<br />
for public use. The l<strong>and</strong>scaping component of such stream <strong>and</strong> riparian restoration projects must be emphasized given its<br />
importance of visual success <strong>and</strong> public perception. The purpose of this technical note is to address l<strong>and</strong>scaping considerations<br />
associated with urban stream <strong>and</strong> riparian restoration projects, <strong>and</strong> provide ideas to managers for enhancing the visual appeal<br />
<strong>and</strong> aesthetic qualities of urban projects.<br />
DTIC<br />
Cities; Ecosystems; Environmental Surveys; Restoration; Streams<br />
20040111965 Computer Sciences Corp., Hampton, VA, USA<br />
Triangulation of NURBS Surfaces<br />
Samareh-Abolhassani, Jamshid; [1994]; 12 pp.; In English; Original contains black <strong>and</strong> white illustrations; No Copyright;<br />
Avail: CASI; A03, Hardcopy<br />
A technique is presented for triangulation of NURBS surfaces. This technique is built upon an advancing front technique<br />
combined with grid point projection. This combined approach has been successfully implemented for structured <strong>and</strong><br />
unstructured grids.<br />
Author<br />
Computational Fluid Dynamics; Computational Grids; Triangulation; Parameterization; Nonuniformity; Surface Geometry<br />
20040111994 <strong>NASA</strong> Langley Research Center, Hampton, VA, USA<br />
Effect of Far-Field Boundary Conditions on Boundary-Layer Transition<br />
Bertolotti, Fabio P.; Joslin, Ronald D.; [1994]; 17 pp.; In English<br />
Contract(s)/Grant(s): NAS1-19480; No Copyright; Avail: CASI; A03, Hardcopy<br />
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