Accession Number:

ADA199378

Title:

Low Reynolds Number - Separation Bubble

Descriptive Note:

Final technical rept. 1 Jul 1984-30 Sep 1987

Corporate Author:

UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES

Personal Author(s):

Report Date:

1987-09-30

Pagination or Media Count:

17.0

Abstract:

This research investigate the flowfield details and global performance characteristics of the transitional separation bubble which typically occurs near the onset of an adverse pressure gradient on airfoils operating at low Reynolds numbers. The present investigation of the flowfield structure associated with the separation bubble phenomenon has been made to examine in more detail the manner in which the bubble affects drag. An investigation has also been made of the effects of external forcing, including free stream turbulence and acoustic disturbances, on the separated flow and transition, since these parameters can lead to changes in performance and may be used to illustrate the effects of the laminar bubble. Experiments concentrated on the flowfield and performance of an LA2573A airfoil operating at chord Reynolds numbers near 250,000. This flow condition is in the lower band of the design range for the airfoil, where adverse effects of the separation bubble were previously shown to be most significant. Global airfoil performance including lift and drag measurements were obtained through pressure distribution measurements around the airfoil contour and through a scan of wake pressures used in computing drag coefficients. Airfoil performance measurements were used for comparisons between cases with forced or unforced external disturbances.

Subject Categories:

  • Aerodynamics
  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE