Flight Experiments on Local and Global Effects of Surface Roughness on 2-D and 3-D Boundary-Layer Stability and Transition; Final rept. 1 Sep 2005-1 Dec 2007

摘要

The work cumulated in a series of laminar-turbulent transition flight-text experiments on a swept wing with the goal of validating the spanwise-periodic distributed roughness elements (DRE) technology in a Reynolds number range applicable to SensorCraft technology. Phase I of the program measured freestream turbulence levels that were nominally 0.05% to 0.06% of the freestream speed and thus established the suitability of the flight environment for the laminarization flights. Phase II of the program did the baseline transition measurements on the airfoil, i.e., with and without DRE technology. The region of laminar flow was extended from 30% to 60% chord at a chord Reynolds number of Rec=8 million and sweep angle of 30 deg.