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  • 1
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    Tone generation by rotor-downstream strut interaction (1984)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 10, p. 1378, Accession no. A83-25957
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: Journal of Aircraft (ISSN 0021-8669); 21; 135-142
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 2
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    Rotor wake characteristics relevant to rotor-stator interaction noise generation (1982)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-18
    Beschreibung: (Previously cited in issue 01, p. 13, Accession no. A82-10456)
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 3
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    Application of coherence in fan noise studies (1980)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: A study of fan noise was made by using the coherence function to obtain far field spectra that were coherent with the fan rotational rate. Choosing fan rotational rate as one of the two variables yielded new information about the far field noise generated during static fan testing. As a result of this coherent data processing, the inlet fan-tone noise present in static testing was determined to be mostly random when the rotor-alone and rotor-stator interaction tones were cut off. After the rotor-alone sound field was cut on, the sound pressure became coherent, and the angular extent of high coherence increased as fan speed was increased. In addition, the sound field was organized as a pattern of lobes whose amplitude varied slowly with time. Additional fan test results indicate that operating the fan with an inflow control device can partially reduce the fan-tone noise levels to those produced by coherent processing.
    Schlagwort(e): ACOUSTICS
    Materialart: NASA-TP-1630 , E-157
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 4
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    Effect of rotor-to-stator spacing on acoustic performance of a full-scale fan (QF-5) for turbofan engines (1974)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: A study was made of the effect of increasing the fan rotor-to-stator spacing on the noise level of a full-scale, single-stage, 1.6-pressure-ratio fan. Noise data were obtained with axial spacing of 1.14, 1.65, and 2.27 rotor chord lengths. Over this spacing range, data indicate a reduction of 1.5 PNdb. Apparently, rotor-alone noise at the frequency at which the rotor-stator interaction noise was cut off limited the noise reduction for the QF-5 fan. It seems, however, that the reduction in sound power level with increases in spacing is potentially about 6 db over the range of spacing tested.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-3103 , E-7879
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 5
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    Acoustic and aerodynamic performance of a 1.5-pressure-ratio, 1.83-meter (6 ft) diameter fan stage for turbofan engines (QF-2) (1977)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The fan was externally driven by an electric motor. Design features for low-noise generation included the elimination of inlet guide vanes, long axial spacing between the rotor and stator blade rows, and the selection of blade-vane numbers to achieve duct-mode cutoff. The fan QF-2 results were compared with those of another full-scale fan having essentially identical aerodynamic design except for nozzle geometry and the direction of rotation. The fan QF-2 aerodynamic results were also compared with those obtained from a 50.8 cm rotor-tip-diameter model of the reverse rotation fan QF-2 design. Differences in nozzle geometry other than exit area significantly affected the comparison of the results of the full-scale fans.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-3521 , E-8968
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 6
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    Acoustic and aerodynamic performance of a 6-foot-diameter fan for turbofan engines. 2 - Performance of QF-1 fan in nacelle without acoustic suppression (1970)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: Low noise turbofan engine without aerodynamic blade loading
    Schlagwort(e): PROPULSION SYSTEMS
    Materialart: NASA-TN-D-6080 , E-5757
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 7
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    Sound measurements on a 4000-pound-thrust high-bypass-ratio turbofan engine (1970)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: Sound measurements on 4000 pound thrust high bypass ratio turbofan engine
    Schlagwort(e): PROPULSION SYSTEMS
    Materialart: NASA-TM-X-1950
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 8
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    Rotor wake characteristics relevant to rotor-stator interaction noise generation (1981)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: Mean and turbulence wake properties at three axial locations behind the rotor of an aerodynamically loaded 1.2 pressure ratio fan were measured using a stationary cross film anemometer in an anechoic wind tunnel. Wake characteristics at four radial immersions across the duct at four different fan speeds were determined utilizing a signal enhancement technique. The shapes of the waveforms of the mean rotor relative and mean upwash velocities were shown to change significantly across the span of the blades. In addition, an increase in fan rotational speed caused an increase in the maximum wake turbulence intensity levels near the hub and tip. Spectral analysis was used to describe the complex nature of the rotor wake.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 81-2031 , Aeroacoustics Conference; Oct 05, 1981 - Oct 07, 1981; Palo Alto, CA
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 9
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    Variation of fan tone steadiness for several inflow conditions (1978)
    In:  CASI
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: An amplitude probability density function analysis technique for quantifying the degree of fan noise tone steadiness has been applied to data from a fan tested under a variety of inflow conditions. The test conditions included typical static operation, inflow control by a honeycomb/screen device and forward velocity in a wind tunnel simulating flight. The ratio of mean square sinusoidal-to-random signal content in the fundamental and second harmonic tones was found to vary by more than an order-of-magnitude. Some implications of these results concerning the nature of fan noise generation mechanisms are discussed.
    Schlagwort(e): ACOUSTICS
    Materialart: NASA-TM-78886 , E-9621 , AIAA PAPER 78-1119 , Fluid and Dyn. Conf.; Jul 10, 1978 - Jul 12, 1978; Seattle
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 10
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    Tone generation by rotor-downstream strut interaction (1983)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: A JT15D fan stage was acoustically tested in the NASA Lewis anechoic chamber as part of the joint Lewis-Langley Research Center investigation of flight simulation techniques and flight effects using the JT15D engine as a common test vehicle. Suspected rotor-downstream support strut interaction was confirmed through the use of simulated support struts which were tested at three axial rotor-strut spacings. Tests were also performed with the struts removed. Inlet boundary layer suction in conjunction with an inflow control device was also explored. The removal of the boundary layer reduced the fan fundamental tone levels suggesting that the mounting and mating of such a device to the nacelle requires careful attention. With the same inflow control device installed good acoustic agreement was shown between the engine on an outdoor test stand and the fan in the anechoic chamber.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 83-0767 , American Institute of Aeronautics and Astronautics, Aeroacoustics Conference; Apr 11, 1983 - Apr 13, 1983; Atlanta, GA
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
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