High-Speed Turbofan Noise Reduction Using Foam-Metal Liner Over-the-Rotor

TLDR

The study documents the test setup and conditions for evaluating foam‑metal liners on a Williams International FJ44‑3A turbofan. The authors tested two foam‑metal liner designs on a Williams International FJ44‑3A turbofan at NASA Glenn’s Aeroacoustic Propulsion Laboratory, comparing them to a hard‑wall baseline and traditional single‑degree‑of‑freedom liners. The foam‑metal liners reduced forward‑quadrant radiated acoustic power by up to 5 dB—matching the performance of conventional single‑degree‑of‑freedom liners—while only modest engine performance changes were observed.

Abstract

A Williams International FJ44-3A turbofan engine was used to demonstrate the high-speed fan noise reduction potential of a foam-metal liner installed in close proximity to the fan rotor. The engine was tested in the NASA Glenn Research Center's Aeroacoustic Propulsion Laboratory. Two foam-metal liner designs were tested and compared to the hardwall baseline. Traditional single degree-of-freedom liner designs were also evaluated to provide a comparison to the state-of-the art design. This report presents the test setup and documents the test conditions. Far-field acoustic levels and limited engine performance results are also presented. The results show that the foam-metal liner achieved up to 5 dB of attenuation in the forward-quadrant radiated-acoustic power levels, which is equivalent to the traditional single degree-of-freedom liner design. Modest changes in engine performance were noted.