Describing the Source Created by Turbulent Flow over Orifices and Louvers.
Abstract
Orifice and louver sound power spectra are investigated, using an intensity probe, at various wind speeds in a low noise, semi-anechoic, subsonic wind tunnel for free stream velocities below 50 meters per second. The radiated noise is created by turbulent flow over various orifice and louver geometries which are flushed mounted into the wall of a long duct. Five orifice samples of rectangular shape and various transverse dimensions as well as four louver samples with multiple rectangular and circular orifices are tested. Also investigated is the effect of the leading and trailing edge angle on the radiated sound power. The scaling laws of the excitation frequencies and the speed/power laws are presented for ratios of the boundary layer thickness to the transverse orifice dimension from 1.01 to 4.29. A detailed theoretical model is developed for rectangular shaped aperture orifices and louvers based on the work by Ffowcs Williams, Nelson, and Corcos.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1987
- Accession Number
- ADA190254
Entities
People
- Glenn E. Cann
Organizations
- Massachusetts Institute of Technology