Open this publication in new window or tab >>2021 (English)Report (Other academic)
Abstract [en]
This report describes wind-tunnel measurements within the RECEPT project to
determine transition behind a single roughness element placed near the leading
edge of a 35 degree swept airfoil at negative (-5 degrees) angle of attack with the
rotation axis parallel to the leading edge. A negative angle of attack decreases the
sensitivity to Tollmien-Schlichting wave-type instabilities and instead makes the
boundary layer flow mainly sensitive to cross-flow instability disturbances.
The airfoil was heated by blowing air through its hollow structure and transition
was detected through infrared (IR) temperature measurements of the airfoil
surface. The physical background behind the detection method is that if transition
occurs, the flow at the wall inside the turbulent wedge behind the roughness element
will have a larger friction than the laminar flow outside and hence a larger
heat transfer, making the wall temperature lower in this region. To confirm the
interpretation of the IR temperature images as well as provide measured boundary
layer parameters additional hot-wire measurements within the boundary layer
were performed at few of the parameters covered by the IR measurements. These
parameters are both related to the roughness elements themselves such as their
diameters and heights as well as free-stream velocities and turbulence levels of
the approaching flow.
Place, publisher, year, edition, pages
Internal Publication: , 2021. p. 71
Series
FP7–AAT-2010-RTD-1 265094 RECEPT
National Category
Engineering and Technology Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-291874 (URN)
Note
QC 20210710
2021-03-222021-03-222022-06-25Bibliographically approved