Theoretical Prediction of Nonlinear Propagation Effects on Noise Signatures Generated by Subconic Or Supersonic Propeller - Or Rotor-blade TipsNational Aeronautics and Space Administration, Scientific and Technical Information Office, 1980 - Acoustical engineering - 16 pages |
Common terms and phrases
abscissas according to equation amplitude and impulse angle better than linear cancellation effect computed examples indicate constant-speed blade tip correlates with experimental cylindrical diam domain analysis equal-area rule ref equation 9a equations for sound experimental results better F-function far-field Harmonic number helicopter instantaneous plane Langley Research Center large-amplitude leading expansion large-amplitude waves linear source theory linear theory linear-theory calculation Mach number NASA near-field signature nonlinear distortion nonlinear effects nonlinear propagation equations nonlinear theory correlates nonlinear theory predicts occur at supersonic osculating plane Performing Organization plane of blades plane of tip predicts a cancellation pressure signature Ray direction ray-tube area Raymond L relative overpressure shape function shock waves significant reduction Spectrum for figure spherical SR-2 blade subsonic tip supersonic speeds supersonic tip swept 30 swept tips term in equation theory for large-amplitude tip is treated tip motion tip noise tip trajectory unit vector Vb² wave with large-amplitude ΔΡ