A Study of Acoustic Disturbances and Means of Suppression in Ventilated Transonic Wind Tunnel Walls
Abstract
An experimental investigation of acoustic disturbances and means of suppression from ventilated transonic wall samples was performed in a low- background-noise research tunnel at AEDC. Configurations for ventilation investigated were longitudinally slotted walls, with and without baffles in the slots, slats versus round rods, and perforated walls with normal or inclined circular holes with varied hole sizes and varied diameter/wall thickness ratio. Comparative acoustic data were acquired over a broad range of subsonic Mach numbers. Several of these wall configurations were found to emit intense, discrete whistling noise with overall root-mean-square amplitudes as large as five percent of the free-stream dynamic pressure. In all cases except one, suppressed noise levels not exceeding 0.75 percent of the free-stream dynamic pressure were achieved compared to a background noise level for the tunnel of approximately 0.47 percent with solid test section walls. Noise suppression was accomplished by means of appropriate devices added to the wall samples which could have application to actual transonic wind tunnel test sections.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1977
- Accession Number
- ADA045347
Entities
People
- N. S. Dougherty Jr.
Organizations
- Arnold Engineering Development Complex