SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

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

07 AIRCRAFT PROPULSION AND POWER
Includes primary propulsion systems and related systems and components, e.g., gas turbine engines, compressors, and fuel systems; and onboard auxiliary power plants for aircraft.

For related information see also 20 Spacecraft Propulsion and Power; 28 Propellants and Fuels; and 44 Energy Production and Conversion.

20060013451 NASA Glenn Research Center, Cleveland, OH, USA

Small Hot Jet Acoustic Rig Validation

Brown, Cliff; Bridges, James; April 2006; 241 pp.; In English; Original contains color illustrations Contract(s)/Grant(s): WBS 22-781-30-62 Report No.(s): NASA/TM-2006-214234; E-15481; No Copyright; Avail.: CASI: A11, Hardcopy

The Small Hot Jet Acoustic Rig (SHJAR), located in the Aeroacoustic Propulsion Laboratory (AAPL) at the NASA Glenn Research Center in Cleveland, Ohio, was commissioned in 2001 to test jet noise reduction concepts at low technology readiness levels (TRL 1-3) and develop advanced measurement techniques. The first series of tests on the SHJAR were designed to prove its capabilities and establish the quality of the jet noise data produced. Towards this goal, a methodology was employed dividing all noise sources into three categories: background noise, jet noise, and rig noise. Background noise was directly measured. Jet noise and rig noise were separated by using the distance and velocity scaling properties of jet noise. Effectively, any noise source that did not follow these rules of jet noise was labeled as rig noise. This method led to the identification of a high frequency noise source related to the Reynolds number. Experiments using boundary layer treatment and hot wire probes documented this noise source and its removal, allowing clean testing of low Reynolds number jets. Other tests performed characterized the amplitude and frequency of the valve noise, confirmed the location of the acoustic far field, and documented the background noise levels under several conditions. Finally, a full set of baseline data was acquired. This paper contains the methodology and test results used to verify the quality of the SHJAR rig. Author

Jet Aircraft Noise; Aeroacoustics; Boundary Layers; Background Noise; Noise Reduction

20060013522 Research and Technology Organization, Neuilly-sur-Seine, France

Micro Gas Turbines

December 2005; In English; Applied Vehicle Technology (AVT/VKI) Panel Lectures Series, 14-18 May 2004, Rhode-Saint-Genese, Belgium; See also 20060013523 - 20060013537 Report No.(s): RTO-EN-AVT-131; AC/323(AVT-131)TP/94; Copyright; Avail.: CASI: C01, CD-ROM

Portable equipment as well as propulsion of small airplanes (UAV) and robots have enhanced the need for portable power supplies of large energy density (kWh/kg). The need for high performance and the specific problems resulting from the miniaturization of components are the motivation for the present lecture series. This course describes the state-of-the-art and gives an overview of the research activities on problems that are specific for micro and nano-gas-turbines, such as large heat fluxes, oil free bearings, high performance and compact heat exchangers, special combustion chamber designs and the use of non-conventional fuels, unconventional materials and appropriate manufacturing techniques, and new electrical generators and motors. It is shown what progress is still needed in all those fields before portable gas-turbine units between .1 and 1 kW will become available. Possible applications of micro-gas-turbines for propulsion of UAV and integration in fuel-cells are also presented. It is concluded that a lot of research is still required before the target of 75% thermal efficiency will be reached for the latter ones. Author

Gas Turbines; Combustion Chambers; Heat Exchangers; Miniaturization; Portable Equipment; Thermodynamic Efficiency

20060013524 Tokyo Univ., Japan

Lessons Learned from the Ultra-Micro Gas Turbine Development at University of Tokyo

Nagashima, Toshio; Micro Gas Turbines; December 2005, pp. 14-1 - 14-58; In English; See also 20060013522; Original contains color and black and white illustrations; Copyright; Avail.: CASI: A04, Hardcopy; Available from CASI on CDROM only as part of the entire parent document

The outcome of NEDO supported international research project led by University of Tokyo is reviewed, with respect to developing key technologies for ultra-micro gas turbines (UMGT). The study suggested Finger-top gas turbines as a currently feasible extreme that install rotors of 8 mm in diameter with 1.2 million rpm to produce tens of watts net output. Prior to practicing such UMGT system integration, Palm-top gas turbine engine of an expected 2 - 3 kWoutput was first prototyped to operate successfully under a measurable control system, using propane as the fuel and installing a compact heat exchanger, which yielded valuable conceptual as well as practical data base for further advancement of UMGT designing. Author

Gas Turbine Engines; Miniaturization; Heat Exchangers; Energy Conversion; Systems Integration; Data Bases; Gas Turbines

20060013526 Tokyo Univ., Japan

Aero-Thermal Research Particulars in Ultra-Micro Gas Turbines

Nagashima, Toshio; Teramoto, Susumu; Kato, Chisachi; Yuasa, Saburo; Micro Gas Turbines; December 2005, pp. 3-1 - 3-38; In English; See also 20060013522; Original contains color and black and white illustrations; Copyright; Avail.: CASI: A03, Hardcopy; Available from CASI on CD-ROM only as part of the entire parent document

Aerodynamics in turbo-components and matched combustor characteristics relating to the design of ultramicro gas turbines (UMGT) were presented. Some detailed analysis were provided for the effects of heat transfer, tip clearance and geometrical restriction imposed to UMGT flow passages, as well as a leading concept of combustor design to achieve micro flame structure for enhanced efficiency and stability. Author

Aerodynamic Heating; Combustion Chambers; Gas Turbines; Heat Transfer; Temperature Effects

20060013537 Von Karman Inst. for Fluid Dynamics, Rhode-Saint-Genese, Belgium

Micro Gas Turbines: A Short Survey of Design Problems

VandenBraembussche, R. A.; Micro Gas Turbines; December 2005, pp. 1-1 - 16; In English; See also 20060013522; Original contains color and black and white illustrations Contract(s)/Grant(s): Proj. SBO-030288; Copyright; Avail.: CASI: A03, Hardcopy; Available from CASI on CD-ROM only as part of the entire parent document

Micro gas turbines have experienced a growing interest during the last decade. Their large energy density (Whr/kg) makes them attractive for portable power units as well as for propulsion of small airplanes (UAV). They are also of interest for distributed power generation in applications where heat and power generation can be combined. The need for high performance in both applications is at the origin of a worldwide interest and research on micro gas turbines and the motivation for the present lecture series. Scaling is a common technique to define larger or smaller geometries with similar characteristics. However a simple scaling of a high performance large gas turbine will not result in a good micro gas turbine. The main factors perturbing such a scaling are: The large change in Reynolds number. Massive heat transfer between the hot and cold components (negligible in large machines). Geometrical restrictions related to material and manufacturing of miniaturized components. The purpose of the present lecture is to provide a first insight into the aero-thermal problems of micro gas turbines. Derived from text

Aerodynamic Heating; Design Analysis; Gas Turbines; Heat Transfer; Miniaturization; Propulsion

Source: NASA