Flight experiments on the effects of step excrescences on swept-wing transition. (1st January 2014)

• Record Type: Journal Article
• Authors: Duncan, Glen T.; Crawford, Brian K.; Tufts, Matthew W.; Saric, William S.; Reed, Helen L.
• Is Part Of: International journal of engineering systems modelling and simulation. Volume 6:Number 3/4(2014)
• Page Start: 171
• Page End: 180
• Publication Date: 2014-01-01
• Subjects: 2-D roughness -- step excrescences -- forward-facing step -- backward-facing step -- boundary-layer transition -- laminar flow -- transport Reynolds number -- flight research -- crossflow instability -- swept wings; Engineering systems -- Computer simulation -- Periodicals; Engineering systems -- Mathematical models -- Periodicals; 620.0042
• Languages: English
• ISSNs: 1755-9758

Abstract

A 30° swept-wing model with a movable, leading-edge extending to 15% chord is used in flight tests to study the effect of two-dimensional, step excrescences on swept-wing transition, where stationary-crossflow waves are typically the dominant instability. Transport unit Reynolds numbers are achieved using a Cessna O-2A Skymaster. Forward- and aft-facing steps are modulated in-flight. Pressure measurements are compared with CFD. Infrared thermography is used to globally detect boundary-layer transition. When the 2-D pressure gradient matches the unswept case, the swept-wing case has a lower Rekk, crit . However, there is still potential to relax conventional, laminar-flow tolerances for steps.