Localized, Non-Harmonic Active Flap Motions for Low Frequency In-Plane Rotor Noise Reduction

Abstract

A first-of-its-kind demonstration of the use of localized, non-harmonic active flap motions, for suppressing low frequency, in-plane rotor noise, is reported in this paper. Operational feasibility is verified via testing of the full-scale AATD/Sikorsky/UTRC active flap demonstration rotor in the NFAC's 40- by 80-Foot anechoic wind tunnel. Effectiveness of using localized, non-harmonic active flap motions are compared to conventional four-per-rev harmonic flap motions, and also active flap motions derived from closed-loop acoustics implementations. All three approaches resulted in approximately the same noise reductions over an in-plane three-by-three microphone array installed forward and near in-plane of the rotor in the nearfield. It is also reported that using an active flap in this localized, non-harmonic manner, resulted in no more that 2% rotor performance penalty, but had the tendency to incur higher hub vibration levels.

Open PDF

Document Details

Document Type
Technical Report
Publication Date
May 01, 2012
Accession Number
ADA558227

Entities

People

  • Ben W. Sim
  • Cahit Kitaplioglu
  • Joseph B Andrews
  • Mark Potsdam
  • Peter Lorber
  • Philip Lemasurier

Organizations

  • National Aeronautics and Space Administration

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Acoustics
  • Aircrafts
  • Control Systems
  • Flaps (Control Surfaces)
  • Frequency
  • Governments
  • Helicopters
  • Mach Number
  • Measurement
  • Microphones
  • Noise
  • Noise Reduction
  • Standing Waves
  • Transducers
  • United States Government
  • Waves
  • Wind Tunnels

Fields of Study

  • Physics

Readers

  • Chemistry (specifically Chemical Fluorescence)
  • Marine Propulsion Engineering and Naval Architecture
  • Quantum Dot Semiconductor Device Photonics and Graphene Optoelectronic Materials and THz Physics.