Modal radiation from an unbaffled rotating disk

Abstract

This paper deals with the acoustic radiation from an unbaffled rotating disk. It is shown that when the disk is rotating, the natural modes are no longer stationary modes but are transformed into rotating waves. Using the concept of rotating waves instead of the retarded time potential method, rotation effects are taken into account in the vibratory part of the problem. Thus no assumption has to be made on the rotation speed and the near pressure field can be evaluated. A new collocation method is proposed to solve the double-layer potential problem which does not require evaluating double-surface integration as when using classical methods. A new analytical formula is established to evaluate the Hadamard finite part of the auto-influent terms. Radiation efficiencies of unbaffled rotating waves are calculated and charts are given which are useful for designing quiet circular disks such as saw blades or rotating wheels. Rotating waves are classified as radiating and nonradiating. The disk is not assumed to be baffled as it is the classical case; therefore, the charts given in this study can be used directly for real cases.

Vibroacoustic analysis of an unbaffled rotating disk

“…On the acoustic radiation, three papers ͑Lee and Singh, 1992Singh, , 1994Beslin and Nicolas, 1996͒ have been found. Those studies were focused mainly on the modal radiation efficiency.…”

Study on Idle Noise Characteristics of Hard Disk Drives Based on a Multibody Dynamic Formulation

“…So far, a few papers have been found on sound radiation from a centrally clamped circular disk vibrating at its elastic modes Singh, 1992a, 1994;Beslin and Nicolas, 1996;Cote et al, 1998). So far, a few papers have been found on sound radiation from a centrally clamped circular disk vibrating at its elastic modes Singh, 1992a, 1994;Beslin and Nicolas, 1996;Cote et al, 1998).…”

Vibro-acoustic interaction of microsystem components in data storage devices

“…On the numerical simulation of acoustic radiation from a HDD, although a substantial body of literature exists concerning the general subject of acoustics (Morse and Ingard, 1968;Pierce, 1981;Beranek and Ver, 1992;Filippi et al, 1999;Fahy, 2001) and sound and structural vibration (Fahy, 1985;Junger and Feit, 1986;Cremer and Heckl, 1988; Ohayon and Soize, 1998), information on the HDD acoustics is limited in open literature although the vibration part have been relatively well covered. So far, a few papers have been found on the sound radiation from a centrally clamped circular disk vibrating at its elastic modes Singh, 1992b, 1994;Beslin and Nicolas, 1996;Cote et al, 1998).…”

“…The modal radiation efficiency of an unbaffled rotating disk in both frames of reference, rotating and non-rotating, have been calculated (Beslin and Nicolas, 1996). The rotation effect was taken into account by using the concept of rotating waves instead of the retarded time potential method.…”