A note on the pressure drag of a forward-swept-wing-plate junction

Abstract

SummaryThe forces due to normal pressure have been measured in the region of the junction between a rear-loaded wing swept forward at 28°, and a flat plate on which a turbulent boundary layer had developed. The Reynolds number was 1·03 × 106, based on the streamwise wing-chord of 500 mm. At low incidences, 0° < α ≤ 6°, the local pressure drag coefficients were found to be negativeaway from the junction, and the interaction with the junction was found to be favourable;that is the pressure drag coefficient became more negative as the junction was approached. At α = −3° the pressure drag coefficient changed from a positive value away from the junction to a negative value close to the plate. These results contrast with those for a swept-back wing-plate interaction, which has been reported as being unfavourable so far as the pressure drag was concerned. At 6° incidence, the interaction remained favourable but there was evidence of root stall beginning. At an incidence of 9°, root stall was much more marked and the positive pressure drag coefficient increased as the junction was approached.