Two-Dimensional Subsonic Wind Tunnel Investigations of a Cambered 30- Percent Thick Circulation Control Airfoil
Abstract
A relatively thick Circulation Control (CC) elliptic airfoil section with thickness-to-chord ratio of 0.30 and a circular arc camber of 1.5 percent at the midchord was tested subsonically to determine its aerodynamic properties as a midspan blade section on a blown helicopter rotor. The two-dimensional tests established the section's ability to generate the required lift at low and negative incidence. Lift coefficients up to 6.5 were produced at moderate momentum coefficient C sub mu equal to or less than 0.24. High drag of the unblown bluff ellipse was greatly reduced by the application of very moderate blowing, and equivalent efficiencies of 47 (including power required for blowing) were generated at C sub l approximately equal to 1.9. The section's performance was found to be heavily influnced by upper and lower aft surface flow separations, especially at the larger positive and negative angles of attack. In addition, both low Reynolds number and an increase in slot height were detrimental to section lift capability. Nevertheless, the ability to operate at high lift coefficients essentially independent of angle of attack, and with large lift augmentation for relatively low blowing, promises to provide an effective blade section for heavy lift application.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1972
- Accession Number
- AD0913411
Entities
People
- David W Taylor
- Robert J. Englar