ABSTRACT
The detection of boundary layer transition on wind tunnel models of commercial transport airplanes has been a long standing requirement at cruise Mach numbers. Establishing the location and height of the trips is a difficult task which requires experimental methods to detect boundary layer transition. Recent advances in the design of high-lift system flap elements have identified a need to observe the natural transition location, and a need for possible extensive use of boundary layer trips on commercial transport high-lift models. The sublimation method can only be applied to one test condition before stopping the wind tunnel and reapplying the indicator. Consequently there has been a strong incentive to develop alternative methods of observing boundary layer transition. Since an infrared camera provides indications of surface temperature, its use as a transition indicator must depend on some connection between the surface temperature and the boundary layer state.
