Design of a Dual Waveguide Normal Incidence Tube (Dwnit) Utilizing Energy and Modal Methods

By: Nasa, National Aeronautics and Space Adm

This report investigates the partition design of the proposed Dual Waveguide Normal Incidence Tube (DWNIT). Some advantages provided by the DWNIT are (1) Assessment of coupling relationships between resonators in close proximity, (2) Evaluation of "smart liners," (3) Experimental validation for parallel element models, and (4) Investigation of effects of simulated angles of incidence of acoustic waves. Energy models of the two chambers were developed to determine the Sound Pressure Level (SPL) drop across the two chambers, through the use of an intensity transmission function for the chamber's partition. The models allowed the chamber's lengthwise end samples to vary. The initial partition design (2" high, 16" long, 0.25" thick) was predicted to provide at least 160 dB SPL drop across the partition with a compressive model, and at least 240 dB SPL drop with a bending model using a damping loss factor of 0.01. The end chamber sample transmissions coefficients were set to 0.1. Since these results predicted more SPL drop than required, a plate thickness optimization algorithm was developed. The results of the algorithm routine indicated that a plate with the same height and length, but with a thickness of 0.1" and 0.05 structural damping loss, would provide an adequate SPL isolation between the chambers.Betts, Juan F. and Jones, Michael G. (Technical Monitor)Langley Research CenterENERGY METHODS; STRUCTURAL VIBRATION; VIBRATION DAMPING; WAVEGUIDES; BENDING; COMPRESSIBILITY; RESONATORS; ALGORITHMS; SOUND PRESSURE

• Format: Paperback
• Language: English
• ISBN: 1723719048
• ISBN13: 9781723719042
• Release Date: January 1
• Publisher: Independently Published
• Length: 40 Pages
• Weight: 0.26 lbs.
• Dimensions: 0.1" x 8.5" x 11.0"