Surface temperature mapping using liquid crystals applied to identifying the laminar-turbulent transition

The determination of the transonic position on a two dimensional model is an important subject of studies in the ONERA-CERT T2 cryogenic wind tunnel. The use of liquid crystals with a specific methodology of calibration, acquisition and image processing allowed one to go beyond the usual stage of qualitative imaging and to determine the temperature map on the surface of the model, the variation in time of this temperature and to know the precise location of the laminar/turbulent transition.