Quiet Technology Demonstrator 2 Intake Liner Design and Validation

This paper describes the collaborative work performed by Goodrich and Boeing to design, build and demonstrate the flight benefit of a one-piece, acoustically smooth engine intake liner. The work is done under the joint Quiet Technology Demonstrator 2 (QTD2) program between Boeing, ANA, GE, Goodrich, and NASA. The focus of the paper is to describe the acoustic features of the Goodrich inlet, show how these features were designed, and give details on the realized benefits. The intake design includes three features that enhance its acoustic performance. These are an acoustically smooth inlet liner with area maximization, acoustically treated inlet lip, and optimized liner configuration designs. The acoustically smooth inlet had a coverage area greater than conventional liners, starting closer to the fan and extending forward as far as the forward bulkhead without axial splices or a T12 probe. Since there are no hard wall splices in the inlet liner, the scattering effect of both the blade passage frequencies (BPF) and the buzz-saw noise tones were minimized. The nose lip liner design is integrated with an advanced ice protection system to both maintain the deicing function and minimize the aero performance losses. The lip liner was targeted to suppress both fan and low pressure compressor (LPC) noise sources. In both inlet and lip liner design, proprietary tools and methods were used to optimize liner designs which met identified acoustic liner performance targets. The noise flight test was conducted at the Glasgow Industrial Airfield located near Glasgow, Montana. Acoustic data was acquired while the airplane performed a series of takeoff and approach flight path intercepts over a microphone array for a number of hardware configurations and power settings. Data were acquired and processed using Boeing's Flight Test Acoustic Data Processing System. These data clearly show that the Goodrich inlet and lip liner provided excellent acoustic benefit for both community and interior noise.