The Boeing Company

Gene Woodard Stubbs

Belur N Shivashankara

Wendell R Miller

William Albert Voll

George H Moffat

An acoustic muffler for a turbine engine exhaust comprises an outer shell of tubular configuration, a tubular liner disposed within the shell, and a plurality of dividing walls extending between the liner and the outer shell so as to divide the generally annular space between the liner and shell into a plurality of chambers circumferentially spaced about the muffler. A central longitudinal axis of the liner is radially offset from the central longitudinal axis of the shell such that the chambers have different depths in a radial direction of the muffler, and the liner has at least one opening into each chamber. Thus, the muffler has a plurality of chambers of different sizes providing noise attenuation at a plurality of specific tuned frequencies, and the liner provides broad band attenuation.

Acoustic muffler for turbine engine

A flush-dish microphone system for measuring aircraft flyover noise is disclosed. The system includes an acoustically hard base supporting a microphone. The base is configured along its periphery to define a plurality of outwardly extending tapered members. Each of the tapered members includes a pair of converging edges that are each at least in part curved. The curved edges produce a favorable progressive match of acoustic impedance at the ground/tapered member boundary that reduces edge diffraction contamination of the noise signal being measured by the microphone.

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Seattle, WA, United States of America

Gene Woodard Stubbs