Issue 10 Volume 41 May 16, 2003

20030032495 NASA Glenn Research Center, Cleveland, OH, USA
A Wind Tunnel Study of Icing Effects on a Business Jet Airfoil
Addy, Harlod E., Jr.; Broeren, Andy P.; Zoeckler, Joesph G.; Lee, Sam; February 2003; 22 pp.; In English; 41st Aerospace
Sciences Meeting and Exhibit, 6-9 Jan. 2003, Reno, NV, USA; Original contains black and white illustrations
Contract(s)/Grant(s): WBS-22-708-20-02
Report No.(s): NASA/TM-2003-212124; NAS 1.15:212124; E-13776; AIAA Paper 2003-0727; No Copyright; Avail: CASI;
A03, Hardcopy
Aerodynamic wind tunnel tests were conducted to study the effects of various ice accretions on the aerodynamic
performance of a 36-inch chord, two-dimensional business jet airfoil. Eight different ice shape configurations were tested. Four
were castings made from molds of ice shapes accreted in an icing wind tunnel. Two were made using computationally
smoothed tracings of two of the ice shapes accreted in the icing tunnel. These smoothed profiles were then extended in the
spanwise direction to form a two-dimensional ice shape. The final two configurations were formed by applying grit to the
smoothed ice shapes. The ice shapes resulted in as much as 48\% reduction in maximum lift coefficient from that of the clean
airfoil. Large increases in drag and changes in pitching moment were also observed. The castings and their corresponding
smoothed counterparts yielded similar results. Little change in performance was observed with the addition of grit to the
smoothed ice shapes. Changes in the Reynolds number (from 3 x 10(exp 6) to 10.5 x 10(exp 6) and Mach number (from 0.12
to 0.28) did not significantly affect the iced-airfoil performance coefficients.
Author
Airfoils; Wind Tunnel Tests; Aircraft Icing; Jet Aircraft; Aerodynamic Characteristics
20030032536 Georgia Inst. of Tech., Atlanta, GA, USA
Large-Eddy/Lattice Boltzmann Simulations of Micro-Blowing Strategies for Subsonic and Supersonic Drag Control
Hwang, Danny P., Technical Monitor; Menon, Suresh; March 2003; 29 pp.; In English; Original contains color illustrations
Contract(s)/Grant(s): NAG3-2653; WU 708-87-23
Report No.(s): NASA/CR-2003-212196; E-13799; NAS 1.26:212196; CCL-02-004; No Copyright; Avail: CASI; A03,
Hardcopy
This report summarizes the progress made in the first 8 to 9 months of this research. The Lattice Boltzmann Equation
(LBE) methodology for Large-eddy Simulations (LES) of microblowing has been validated using a jet-in-crossflow test
configuration. In this study, the flow intake is also simulated to allow the interaction to occur naturally. The Lattice Boltzmann
Equation Large-eddy Simulations (LBELES) approach is capable of capturing not only the flow features associated with the
flow, such as hairpin vortices and recirculation behind the jet, but also is able to show better agreement with experiments when
compared to previous RANS predictions. The LBELES is shown to be computationally very efficient and therefore, a viable
method for simulating the injection process. Two strategies have been developed to simulate multi-hole injection process as
in the experiment. In order to allow natural interaction between the injected fluid and the primary stream, the flow intakes for
all the holes have to be simulated. The LBE method is computationally efficient but is still 3D in nature and therefore, there
may be some computational penalty. In order to study a large number or holes, a new 1D subgrid model has been developed
that will simulate a reduced form of the Navier-Stokes equation in these holes.
Author
Aerodynamic Drag; Large Eddy Simulation; Boltzmann Distribution; Supersonic Drag; Subsonic Speed; Boltzmann Transport
Equation; Subsonic Flow; Vortices; Cross Flow; Drag Reduction
20030032963 Virginia Polytechnic Inst. and State Univ., Blacksburg, VA, USA
An Experimental Investigation of Unsteady Surface Pressure on an Airfoil in Turbulence
Mish, Patrick F.; Devenport, William J.; March 31, 2003; 228 pp.; In English; Original contains color illustrations
Contract(s)/Grant(s): NAG-1-2272; No Copyright; Avail: CASI; C01, CD-ROM; A11, Hardcopy
Measurements of fluctuating surface pressure were made on a NACA 0015 airfoil immersed in grid generated turbulence.
The airfoil model has a2ftchord and spans the 6 ft Virginia Tech Stability Wind Tunnel test section. Two grids were used
to investigate the effects of turbulence length scale on the surface pressure response. A large grid which produced turbulence
with an integral scale 13\% of the chord and a smaller grid which produced turbulence with an integral scale 1.3\% of the
chord. Measurements were performed at angles of attack, alpha from 0 to 20 . An array of microphones mounted subsurface
was used to measure the unsteady surface pressure. The goal of this measurement was to characterize the effects of angle of
attack on the inviscid response. Lift spectra calculated from pressure measurements at each angle of attack revealed two
distinct interaction regions; for omega(sub r) = omega b / U(sub infinity) is less than 10 a reduction in unsteady lift of up to
7 decibels (dB) occurs while an increase occurs for omega(sub r) is greater than 10 as the angle of attack is increased. The
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