Abstract
The state of the art is such that all free-field rotors, including helicopters, propellers and fans, produce acoustic spectra which fall short of matching existing theories; in particular, discrete radiation cannot be predicted accurately. The theory described here proposes that rotational noise is the dominant rotor noise mechanism and neglects vortex noise as being an appreciable noise source at normal operating conditions. This theory now predicts radiation which is basically in agreement with such measured parameters as fundamental level, harmonic fall-off, directivity and tip speed dependence. Although the theory has been developed and applied successfully to a particular rotor (helicopter), the theory is quite general and can be adopted to suit any free-field rotary momentum changing device.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
