SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 11 - MAY 30, 2006

02 AERODYNAMICS
Includes aerodynamics of flight vehicles, test bodies, airframe components and combinations, wings, and control surfaces.

Also includes aerodynamics of rotors, stators, fans, and other elements of turbomachinery.

For related information see also 34 Fluid Mechanics and Thermodynamics.

20060013246 Nanjing Univ. of Aeronautics and Astronautics, Nanjing, China

Journal of Nanjing University of Aeronautics & Astronautics, Volume 38, Number 1, February 2006

Dewang, L.; Feb. 2006; 140 pp.; In Chinese Report No.(s): PB2006-104466; Copyright; Avail.: National Technical Information Service (NTIS)

Partial Contents: General Parameter Optimization of Tandem Helicopter Based on Improved Genetic Algorithm, Diagnosis of Worn Pitch-Change-Link Rod End in Helicopter Rotor System, Ion Implantation for Improving Survivability of Helicopter Gear Transmission Under Oil-Out Condition, Residual Strength of Plates with Multiple Collinear Cracks, Dynamic Moving Load Identification Method for Bridge Structure, Autonomous Control System Design for Aerospace Vehicle Using Multi-Agent System, Application of H Control and Inverse Dynamic System in Direct Side Force Control of UAV, Attitude Measurement Using Quaternion Based on UKF, Modeling and Scheduling of Real-Time Tasks in Multiple Segment Network Control Systems, Analysis of DC Output Voltage Ripple in Electromagnetic Doubly Salient Brushless DC Generator, Optimization of Auxiliary Poles in IPM Synchronous Machine, Analysis and Realization of Digitally Controlled Doubly Salient Permanent Magnet Motor Driver, Isolated Boost Full Bridge Converter for Fuel Cell Electric Vehicle, Mobile Robot Navigation Control Based on Hierarchical Reinforcement Learning, Dynamics Analysis of Hopping Robots, Subspace-Based Semi-Blind Channel Estimation for STBC-OFDM Systems. NTIS

Aeronautics; Astronautics; Automatic Control

20060013450 QSS Group, Inc., Cleveland, OH, USA

Effects of Transducer Installation on Unsteady Pressure Measurements on Oscillating Blades

Lepicovsky, Jan; April 2006; 18 pp.; In English; Turbo Expo 2005, 6-9 Jun. 2005, Reno, NV, USA; Original contains color and black and white illustrations Contract(s)/Grant(s): NAS3-00145; WBS 22-714-70-52 Report No.(s): NASA/CR-2006-213797; GT-2005-69000; E-15155; No Copyright; Avail.: CASI: A03, Hardcopy

Unsteady pressures were measured above the suction side of a blade that was oscillated to simulate blade stall flutter. Measurements were made at blade oscillation frequencies up to 500 Hz. Two types of miniature pressure transducers were used: surface-mounted flat custom-made, and conventional miniature, body-mounted transducers. The signals of the surface-mounted transducers are significantly affected by blade acceleration, whereas the signals of body-mounted transducers are practically free of this distortion. A procedure was introduced to correct the signals of surface-mounted transducers to rectify the signal distortion due to blade acceleration. The signals from body-mounted transducers, and corrected signals from surface-mounted transducers represent true unsteady pressure signals on the surface of a blade subjected to forced oscillations. However, the use of body-mounted conventional transducers is preferred for the following reasons: no signal corrections are needed for blade acceleration, the conventional transducers are noticeably less expensive than custom-made flat transducers, the survival rate of body-mounted transducers is much higher, and finally installation of body-mounted transducers does not disturb the blade surface of interest. Author

Pressure Measurement; Aerodynamic Stalling; Unsteady Flow; Transducers; Oscillations; Pressure Sensors; Forced Vibration; Signal Distortion; Surface Distortion

20060013452 NASA Glenn Research Center, Cleveland, OH, USA

Fan Performance From Duct Rake Instrumentation on a 1.294 Pressure Ratio, 725 ft/sec Tip Speed Turbofan Simulator Using Vaned Passage Casing Treatment

Fite, E. Brian; April 2006; 63 pp.; In English; Original contains color illustrations Contract(s)/Grant(s): WBS 581.02.08.03.03.01 Report No.(s): NASA/TM-2006-214241; E-15487; No Copyright; Avail.: CASI: A04, Hardcopy

A 1.294 pressure ratio, 725 ft/sec tip speed, variable pitch low noise fan was designed and tested in the NASA Glenn 9- by 15-footWind Tunnel. The design included a casing treatment that used recirculation to extend the fan stall line and provide an acceptable operating range. Overall aerodynamic experimental results are presented for this low tip speed, low noise fan without casing treatment as well as using several variants of the casing treatment that moved the air extraction and insertion axial locations. Measurements were made to assess effects on performance, operability, and noise. An unusual instability was discovered near the design operating line and is documented in the fan operating range. Measurements were made to compare stall margin improvements as well as measure the performance impact of the casing treatments. Experimental results in the presence of simulated inlet distortion, via screens, are presented for the baseline and recirculation casing treatment configurations. Estimates are made for the quantity of recirculation weight flow based on limited instrumentation in the recirculation system along with discussion of results and conclusions Author

Turbofans; Distortion; Ducts; Extraction; Aerodynamics; Low Noise; Fan Blades; Pressure Ratio

20060013459 NASA Langley Research Center, Hampton, VA, USA

Further Investigation of Acoustic Propagation Codes for Three-Dimensional Geometries

Nark, Douglas M.; Watson, Willie R.; Jones, Michael G.; January 2006; 17 pp.; In English; 12th AIAA/CEAS Aeroacoustics Conference, 8-10 May 2006, Cambridge, MA, USA; Original contains color illustrations Contract(s)/Grant(s): 23-781-30-14 Report No.(s): AIAA Paper 2006-2586; No Copyright; Avail.: CASI: A03, Hardcopy

The ability to predict fan noise within complex three-dimensional aircraft engine nacelle geometries is a valuable tool in designing and assessing low-noise concepts. This work begins a systematic study to identify the areas of the design space in which propagation codes of varying fidelity may be used effectively to provide efficient design and assessment. An efficient lower-fidelity code is used in conjunction with two higher-fidelity, more computationally intensive methods to solve benchmark problems of increasing complexity. The codes represent a small sampling of the current propagation codes available or under development. Results of this initial study indicate that the lower-fidelity code provides satisfactory results for cases involving low to moderate attenuation rates, whereas, the two higher-fidelity codes perform well across the range of problems. Author

Acoustic Propagation; Aerodynamic Noise; Low Noise; Fan Blades

Source: NASA