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  • 1
    Electronic Resource
    Electronic Resource
    Photochemical interconversion of cyclooctatetraene bond shift isomers (1968)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 90 (1968), S. 7130-7132 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja01027a048
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Photochemical interconversion of cyclooctatetraene bond shift isomers (1968)
    American Chemical Society
    Details
    Publication Date: 1968-12-01
    Print ISSN: 0002-7863
    Electronic ISSN: 1520-5126
    Topics: Chemistry and Pharmacology
    Published by American Chemical Society
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    PAPER CURRENT
  • 3
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    Model ducted propulsor noise characteristics at takeoff conditions (1994)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: A model Advanced Ducted Propulsor (ADP) was tested in the NASA Lewis Low-Speed Anechoic Wind Tunnel at a simulated takeoff velocity of Mach 0.2. The model was designed and manufactured by Pratt & Whitney. The 16-blade rotor ADP was tested with 22- and 40-vane stators to achieve cut-on and cut-off criterion with respect to propagation of the fundamental rotor-stator interaction tone. Additional test parameters included three inlet lengths, three nozzle sizes, two spinner configurations, and two rotor rub strip configurations. The model was tested over a range of rotor blade setting angles and inlet angles of attack. Acoustic data were taken with a sideline translating microphone probe and with a unique inlet microphone probe that identified inlet rotating acoustic modes. The beneficial acoustic effects of cut-off were clearly demonstrated. A 10-dB fundamental tone reduction was associated with the long inlet and 40-vane stator. The fundamental tone level was essentially unaffected by inlet angle of attack at rotor speeds of above 96% design.
    Keywords: ACOUSTICS
    Type: Journal of Aircraft (ISSN 0021-8669); 31; 5; p. 1064-1070
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Far-field noise and internal modes from a ducted propeller at simulated aircraft takeoff conditions (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The ducted propeller offers structural and acoustic benefits typical of conventional turbofan engines while retaining much of the aeroacoustic benefits of the unducted propeller. A model Advanced Ducted Propeller (ADP) was tested in the NASA Lewis Low-Speed Anechoic Wind Tunnel at a simulated takeoff velocity of Mach 0.2. The ADP model was designed and manufactured by the Pratt and Whitney Division of United Technologies. The 16-blade rotor ADP was tested with 22- and 40-vane stators to achieve cut-on and cut-off criterion with respect to propagation of the fundamental rotor-stator interaction tone. Additional test parameters included three inlet lengths, three nozzle sizes, two spinner configurations, and two rotor rub strip configurations. The model was tested over a range of rotor blade setting angles and propeller axis angles-of-attack. Acoustic data were taken with a sideline translating microphone probe and with a unique inlet microphone probe which identified inlet rotating acoustic modes. The beneficial acoustic effects of cut-off were clearly demonstrated. A 5 dB fundamental tone reduction was associated with the long inlet and 40-vane sector, which may relate to inlet propeller axis angle-of-attack at rotor speeds of at least 96 percent design.
    Keywords: ACOUSTICS
    Type: AIAA PAPER 92-0371
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    Cruise noise measurements of a scale model advanced ducted propulsor (1993)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A scale model Advanced Ducted Propulsor (ADP) was tested in NASA Lewis Research Center's 8- by 6-Foot Wind Tunnel to obtain acoustic data at cruise conditions. The model, designed and manufactured by Pratt & Whitney Division of United Technologies, was tested with three inlet lengths. The model has 16 rotor blades and 22 stator vanes, which results in a cut-on condition with respect to rotor-stator interaction noise. Comparisons of the noise directivity of the ADP with that of a previously tested high-speed, unducted propeller showed that the ADP peak blade passing tone was about 30 dB below that of the propeller, and therefore, should not present a cabin or enroute noise problem. The maximum blade passing tone first increased with increasing helical tip Mach number, peaked, and then decreased at a higher Mach number. The ADP tests with the shortest inlet showed more noise in the inlet arc than did tests with either of the other two inlet lengths.
    Keywords: ACOUSTICS
    Type: NASA-TM-105808 , E-8042 , NAS 1.15:105808 , AIAA PAPER 93-4400 , AIAA Aeroacoustics Conference; Oct 25, 1993 - Oct 27, 1993; Long Beach, CA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Far-field noise and internal modes from a ducted propeller at simulated aircraft takeoff conditions (1992)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The ducted propeller offers structural and acoustic benefits typical of conventional turbofan engines while retaining much of the aeroacoustic benefits of the unducted propeller. A model Advanced Ducted Propeller (ADP) was tested in the NASA Lewis Low-Speed Anechoic Wind Tunnel at a simulated takeoff velocity of Mach 0.2. The ADP model was designed and manufactured by the Pratt and Whitney Division of United Technologies. The 16-blade rotor ADP was tested with 22- and 40-vane stators to achieve cut-on and cut-off criterion with respect to propagation of the fundamental rotor-stator interaction tone. Additional test parameters included three inlet lengths, three nozzle sizes, two spinner configurations, and two rotor rub strip configurations. The model was tested over a range of rotor blade setting angles and propeller axis angles-of-attack. Acoustic data were taken with a sideline translating microphone probe and with a unique inlet microphone probe which identified inlet rotating acoustic modes. The beneficial acoustic effects of cut-off were clearly demonstrated. A 5 dB fundamental tone reduction was associated with the long inlet and 40-vane sector, which may relate to inlet duct geometry. The fundamental tone level was essentially unaffected by propeller axis angle-of-attack at rotor speeds of at least 96 percent design.
    Keywords: ACOUSTICS
    Type: NASA-TM-105369 , E-6747 , NAS 1.15:105369 , AIAA PAPER 92-0371 , Aerospace Sciences Meeting and Exhibit; Jan 06, 1992 - Jan 09, 1992; Reno, NV; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    Some Acoustic Results from the Pratt and Whitney Advanced Ducted Propulsor: Fan 1 (1999)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Noise measurements were obtained for the Advanced Ducted Propulsor (ADP) - Fan 1, with and without nacelle acoustic treatment. The fan was tested with no acoustic treatment (hard wall) and with acoustic treatment installed in three configurations in the nacelle (mid, mid plus aft, fully treated). The hard wall results showed that the radiated noise from the fan came primarily from the aft end of the nacelle. At takeoff and higher speeds, the noise measured at the inlet angles was also found to be dominated by noise from the aft end. Significant amounts of attenuation were observed with acoustic treatment installed and comparison with predictions showed the treatment gave more attenuation than predicted. Effective Perceived Noise Levels were determined for a large hypothetical 4 engine airplane. These levels showed that the installed acoustic treatment provided as much as 5 EPNdB of noise reduction. A traverse with a probe having three microphones, one above the other, showed azimuthal variations in the noise that need to be further investigated.
    Keywords: Acoustics
    Type: NASA/TM-1999-209049 , NAS 1.15:209049 , E-11582
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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