Directional sensitivity of skin friction measurements using nematic liquid crystal

The directional sensitivity of a new liquid crystal technique for aerodynamic skin friction measurements has been assessed. Experiments were performed using a turntable device installed in a laminar flow duct. Nematic liquid crystal was deposited onto the centre of the turntable. Various initial liquid crystal layer orientations (turntable angles) and magnitudes of applied skin friction were investigated. The dynamic and steady state responses were measured using the transmission of polarized monochromatic light. Steady state predictions based on a simple director model are shown to be in reasonable agreement with the experimental results. (Original abstract - amended)