TIP VORTEX CORE THICKENING FOR APPLICATION TO HELICOPTER ROTOR NOISE REDUCTION

Abstract

Helicopter rotor noise levels are sharply increased when a rotor blade intercepts the rolled-up tip vortex trailed by a previous blade. The study deals with modification of the induced velocity structure of the vortex from both an analytical and an experimental standpoint. Ten tip configurations were evaluated in a wind tunnel, to determine the magnitude of velocity reduction achievable. Results indicated that the maximum velocities induced within the vortex core could be reduced to about 12 percent of those for a standard tip (formed by revolving the tip airfoil section about the chord-line and typical for many present generation helicopters). Drag data measured on the model wing for each blade tip indicates that most configurations adversely affect performance.

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Document Details

Document Type
Technical Report
Publication Date
Sep 01, 1966
Accession Number
AD0644317

Entities

People

  • B. W. Mccormick
  • H. Sternfeld Jr.
  • R. H. Spencer

Organizations

  • Boeing Rotorcraft Systems

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Aircrafts
  • Army Aviation
  • Aspect Ratio
  • Blade Tips
  • Boundary Layer
  • Contracts
  • Flow
  • Fluid Dynamics
  • Free Stream
  • Helicopter Rotors
  • Measurement
  • Noise Reduction
  • Reynolds Number
  • Standards
  • Trailing Vortices
  • Wind Tunnels
  • Wing Tips

Fields of Study

  • Physics

Readers

  • Aerodynamics.
  • Systems Analysis and Design