论文信息 - Flight Test of Active Gear-Mesh Noise Control on the S-76 Aircraft

Flight Test of Active Gear-Mesh Noise Control on the S-76 Aircraft

Active noise control (ANC) offers significant potential for reducing cabin noise levels in helicopters, thereby enhancing ride quality and improving commercial acceptance. One of the most irritating components of helicopter interior noise comes from high frequency (>500Hz) structureborne gear-mesh tones generated within the transmission. Sikorsky Aircraft Corporation is engaged in a multi-year program to develop a flightworthy ANC system to actively cancel gear-mesh noise in the S-76 helicopter interior. The challenge in this ANC application stems from the high frequencies involved; from 700 Hz to 4 kHz. A major project milestone was reached in 1995 with the first flight test of a high frequency ANC system on a helicopter. In this initial flight test, reductions of 7-12dB in the primary gear-mesh tone (~800Hz) were achieved over a wide range of flight conditions. A second flight test, performed in 1996-97, achieved significant improvements in system performance and robustness by utilizing an improved system identification procedure. In this second flight test, 10-20dB reductions in the primary gear-mesh tone were achieved over a wide range of steady and transient flight conditions. This paper includes: (1) a description of the system architecture and control algorithms; (2) a brief summary of the development and ground-testing of the flight-worthy ANC system; (3) a description of the flight test set-up and procedure; and (4) a summary of the flight test results demonstrating the performance and robustness of the ANC system. This ANC system will provide noise suppression and create a quieter passenger environment in the Sikorsky S-92 Helibus ÿ. __________________________________ Presented at the American Helicopter Society 54 th Annual Forum, Washington, DC, May 20-22, 1998. Copyright 1998 by the American Helicopter Society, Inc. All rights reserved. NOTATION J Quadratic cost functional Q Main rotor torque T Actuator/sensor transfer function matrix u Vector of control outputs ∆u Change in control output vector VCR Cruise speed VH Flight speed at maximum power w Measurement noise Wu Control weighting matrix Wδu Control rate weighting matrix Yk Control update matrix z Vector of sensor measurements ∆z Change in sensor measurement vector z0 Ambient sensor measurement vector β Control convergence parameter

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