Documents Home
View PDF, DOC, PPT, and XLS files on line

Add NWW documents to your site (click here)

Sign up for daily updates

Keep Wind Watch online and independent!

News Watch

Selected Documents

Research Links


Press Releases


Publications & Products

Photos & Graphics


Allied Groups

Acoustic interaction as a primary cause of infrasonic spinning mode generation and propagation from wind turbines  

Author:  | Noise, Technology

Abstract. Relatively balanced load related pressure waves from the rear surface of each rotor blade, are at a frequency of 1 per revolution of the turbine and are phase shifted by 120 degrees from each other. The superpositions of these infrasonic waves destructively interfere. This action results in a non-propagating rotor locked mode, however, the shielding (reflecting) effect of the tower as each blade passes, interrupts the balanced destructive interference for a small portion of rotor angle three times per revolution. The momentary un-balance between the destructive interfering waves, results in the generation of Tyler-Sofrin spinning mode series, which propagate into the far field. The spinning mode radiation angles, coupled with the low decay rate of infrasound, result in higher far field sound pressure levels than would be predicted for a point source. An analysis approach partially derived from Tyler-Sofrin (1962) is presented. Field microphone data including phase measurements identifying the spinning modes are also presented.

Kevin A. Dooley, Kevin Allan Dooley Inc., Toronto, Ontario, Canada.
Andy Metelka, Sound and Vibrations Solutions Inc., Acton, Ontario, Canada.

The Journal of the Acoustical Society of America 2013; 134: 4097.
doi: 10.1121/1.4830965

Download draft document (Dec. 9, 2013): “Acoustic interaction as a primary cause of infrasonic spinning mode generation and propagation from wind turbines

This material is the work of the author(s) indicated. Any opinions expressed in it are not necessarily those of National Wind Watch.

The copyright of this material resides with the author(s). As part of its noncommercial effort to present the environmental, social, scientific, and economic issues of large-scale wind power development to a global audience seeking such information, National Wind Watch endeavors to observe “fair use” as provided for in section 107 of U.S. Copyright Law and similar “fair dealing” provisions of the copyright laws of other nations. Queries e-mail.

Wind Watch relies entirely
on User Funding
Donate $5 PayPal Donate


Get the Facts Follow Wind Watch on Twitter

Wind Watch on Facebook


© National Wind Watch, Inc.
Use of copyrighted material adheres to Fair Use.
"Wind Watch" is a registered trademark.