Accession Number:

AD0435764

Title:

VORTEX-SHEDDING SOUNDS OF PROPELLERS,

Descriptive Note:

Corporate Author:

BOLT BERANEK AND NEWMAN INC CAMBRIDGE MASS

Personal Author(s):

Report Date:

1964-03-16

Pagination or Media Count:

66.0

Abstract:

Equations developed in 1956 by Phillips and by Etkin, Korbacher and Keefe for the sound intensity associated with vortex shedding are simplified through the use of hydrodynamical relationships between the Strouhal number, the oscillating lift, and the drag coefficient. It is shown that, besides the Mach number, the only factor influencing the efficiency of conversion of hydromechanical power into acoustical power is the spanwise coherency of the vortex shedding. For a rigid body, this coherent length is only about three times the transverse vortex spacing, but when a body vibrates, it will tend to be almost as long as the body itself. This effect plays a dominant role in the phenomenon of propeller singing. This report includes a literature review of about 110 articles on various aspects of vortex shedding as well as a bibliography of some 130 items. Author

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE