Accession Number:

ADA153233

Title:

Low Reynolds Number Vehicles

Descriptive Note:

Corporate Author:

ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT NEUILLY-SUR-SEINE (FRANCE)

Personal Author(s):

Report Date:

1985-02-01

Pagination or Media Count:

76.0

Abstract:

Recent interest in a wide variety of low Reynolds number configurations has focused attention on the design and evaluation of efficient airfoil sections at chord Reynolds numbers from about 100,000 to about 1,000, 000. These configurations include remotely piloted vehicles RPVs at high altitudes, sailplanes, ultra-light man-carryingman-powered aircraft, mini-RPVs at low altitudes and wind turbinespropellers. A study is presented of the present status and future possibility of airfoil design and evaluation at subcritical speeds to meet the needs for these applications. Although the design and evaluation techniques for airfoil sections above chord Reynolds numbers of 500,000 is reasonably well developed, serious problems related to boundary layer separations and transition have been encountered below RC 500,000. Presently available design and analysis methods need to improve their criteria for laminar separation, transition, and turbulent separation. Improved mathematical models of these complex phenomena require additional, very careful experimental studies. Because of the sensitivity of the low Reynolds number airfoil boundary layer to free stream and surface-generated disturbances, definitive experiments are very difficult. Also the physical quantities measured i.e., pressure difference and drag forces etc. are very small and the accuracy of such measurements depends on the method used. The results from numerous experimental studies are presented to illustrate the type of difficulties encountered.

Subject Categories:

  • Aerodynamics
  • Test Facilities, Equipment and Methods
  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE