## Analytical investigation of fan tone noise due to ingested atmospheric turbulence, Volume 3302National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1980 - Technology & Engineering - 144 pages |

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### Contents

Schematic Spectrum of Wind Speed Near the Ground From a Study of Van DerHoven 1957 From Ref 18 | 12 |

Values for Surface Roughness Scale ZQ From Ref 22 | 14 |

NonNeutral Stability Correction to Mean Wind Profile t2 ZC From Ref 16 | 17 |

19 other sections not shown

### Common terms and phrases

altitude angle of attack approach power atmospheric boundary layer atmospheric turbulence blade passing frequency contraction ratios convected turbulence correlation function distortion elements duct radii due to atmospheric due to convected equations exponents fan duct fan noise due fan rotor fan tone noise flight conditions flow contraction Function of Transverse harmonics inlet angle integral length scales isotropic JT9D mean square mode mean wind velocity Narrowband Sound Power number of rotor Poisson distributed radial order radius represent rotor tone noise scale distribution Section shear stress shown in Figure Sound Power Level sound pressure field Sound Pressure Level spectra square mode amplitude standard deviations static and flight static conditions static pressure streamtube streamwise turbulence component surface roughness scale tip Mach number tone noise due transducers transverse integral scales transverse scales transverse turbulence component turbulence field turbulence intensities turbulence model turbulence variance turbulence velocity component turbulent energy velocity scale vortex field vortices wavenumber