A Traversable Flow Probe to Measure Laminar Boundary Layer Properties over Suction Skins

Abstract

A traverseable flow probe was developed to measure boundary layer data for laminar boundary layers over suction skins. Boundary layer data is a key to verify transition predictions and to exactly trace the development of instabilities in laminar boundary layers. Measurement of boundary layer data is particularly intricate over micro-porous surfaces used for laminar flow control, because any probe must me mounted well downstream of the suction area. The probe presented herein can traverse a single-element hot-wire in, both, streamwise and wall-normal direction over distances of 365mm and 52 mm, respectively, with a stiffness and accuracy making it suitable to measure velocity profiles of boundary layers, but also amplitude functions of Tollmien-Schlichting waves. The probe is modular and can be used in two different large-scale experimental setups with flat plates. Some boundary layer profiles, including suction for laminar flow control, will be shown taken from an entry in the wind tunnel MUB.