Two-Stage Low Noise Advanced Technology Fan I. Aerodynamic, Structural, and Acoustic Design

摘要

A two-stage fan was designed to reduce noise as much as 20 dB below current requirements. The first-stage rotor has a design tip speed of 365.8 m/sec (1200 ft/sec) and a hub/tip ratio of 0.4. The fan was designed to deliver a pressure ratio of 1.9 with an adiabatic efficiency of 85.3 percent at a specific inlet corrected flow of 209.2 kg/sec/m2 (42.85 lbm/sec/ft2). Noise reduction devices include acoustically treated casing walls, a flowpath exit acoustic splitter, a translating centerbody sonic inlet device, widely spaced blade rows, and the proper ratio of blades and vanes. Other features include multiple-circular-arc rotor airfoils, resettable stators, split outer casings, and capability to go to close blade-row spacing.