Sinayoko, S and Joseph, P and McAlpine, A (2010) Multimode radiation from an unflanged, semi-infinite circular duct with uniform flow. J Acoust Soc Am, 127. pp. 2159-2168.Full text not available from this repository.
Multimode sound radiation from an unflanged, semi-infinite, rigid-walled circular duct with uniform subsonic mean flow everywhere is investigated theoretically. The multimode directivity depends on the amplitude and directivity function of each individual cut-on mode. The amplitude of each mode is expressed as a function of cut-on ratio for a uniform distribution of incoherent monopoles, a uniform distribution of incoherent axial dipoles, and for equal power per mode. The directivity function of each mode is obtained by applying a Lorentz transformation to the zero-flow directivity function, which is given by a Wiener-Hopf solution. This exact numerical result is compared to an analytic solution, valid in the high-frequency limit, for multimode directivity with uniform flow. The high-frequency asymptotic solution is derived assuming total transmission of power at the open end of the duct, and gives the multimode directivity function with flow in the forward arc for a general family of mode amplitude distribution functions. At high frequencies the agreement between the exact and asymptotic solutions is shown to be excellent.
|Uncontrolled Keywords:||Acoustics Computer Simulation Engineering Equipment Design Models, Theoretical Motion Noise Numerical Analysis, Computer-Assisted Pressure|
|Divisions:||Div A > Fluid Mechanics|
|Depositing User:||Cron Job|
|Date Deposited:||20 Dec 2011 10:10|
|Last Modified:||30 Dec 2013 01:23|
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