Influence of Karman Vortex Street on the Broad Band Noise Generated from a Multi-Blade Fan

Autor:	Yoshio Kodama, Makoto Hatakeyama, Souichi Sasaki
Rok vydání:	2005
Předmět:	Physics Internal flow Mechanical Engineering Acoustics Wake Condensed Matter Physics Kármán vortex street Vortex Physics::Fluid Dynamics Lift (force) symbols.namesake Frequency domain symbols Strouhal number Sound pressure
Zdroj:	TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B. 71:2686-2693
ISSN:	1884-8346 0387-5016
DOI:	10.1299/kikaib.71.2686
Popis:	In the prediction theory for the broadband noise generated from a multi-blade fan, the vortices in the Karman vortex street was divided into n pieces. The local lift produced by the multiple vortices was substituted for the sound pressure of the fan noise. The frequency distribution of the noise was estimated so that the Strouhal number could become constant even if the wake is spread by the diffusion. From the results of the measurement of the internal flow of the fan, it was found that the noise was related to the wake characteristics of the specific location in the scroll casing where the relative velocity was high. The noise operating in the vicinity of the maximum efficiency point of the fan was distributed over the domain from 500 Hz to 1250 Hz. The sound pressure within the frequency domain was in proportion to the sixth power of the flow rate coefficient, and it was inversely proportional to the second power of the frequency. It was experimentally proved that the influence of the Karman vortex street on the noise in the domains of high and low frequencies did not exist when the distribution of the estimated sound pressure level corresponded to the measured broadband noise.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::7ec164b165225b0cc6ea7cc7914ac964 https://doi.org/10.1299/kikaib.71.2686 Zobrazit plný text záznamu