Adaptive Turbofan Noise Active Control

To address the U.S. Navy need to reduce turbofan/turboprop noise by more than 20 dB, Physical Optics Corporation (POC) proposes to develop an innovative hybrid active/passive Adaptive Turbofan Noise Active Control (ATNAC) system, consisting of a reactive noise suppression device plus a nonlinear active control module based on cascaded neural networks. By instant nonlinear adaptation to coupled, time-varying fan noise, ATNAC can establish an acoustic radiation model of the turbofan engine noise caused by turbulent flow compression/discharge even in realistic, unpredictable aeroacoustic environments. The nonlinear active control module, based on noise profiles from the acoustic radiation model, will rapidly eliminate engine noise by flexibly controlling multiple hybrid skin-like arrays of active and passive actuators. The ATNAC hybrid skin-like reactive actuator devices will be compact and power efficient. In Phase I, POC will optimize the system configuration and methodology, and will design algorithms and hardware specifications for ATNAC. POC will then demonstrated the feasibility of performing instantaneous, omnidirectional, adaptive time-varying modeling for active noise cancellation by means of hybrid reactive noise suppression actuators. ATNAC technology will have widespread applications in both the government and commercial sectors. It will be a valuable tool for controlling acoustic noise and vibration in a wide variety of platforms and structures. Potential users of this technology include the military, the aerospace industry, structural engineering firms for earthquake protection of buildings and other structures, and precision machinery firms.