Acenapthene sublimation is a standard visualisation technique used in the ARA Transonic Wind Tunnel (TWT) to detect the position of transition from laminar to turbulent flow on the model surface. It is an effective tool for checking the performance of model transition bands or dots, which are used to fix the point of transition at a desired location on the model.
The model surface is prepared by spraying a solution of napthelene crystals onto the area of interest. The tunnel is run at the desired condition and the change in flow at the point of transition causes the crystals to be removed behind the point of transition. This can then be imaged post-run as clearly shown in this image.
ARA can also utilise new techniques such as Temperature-Sensitive Paint (TSP) and IR Thermal Imaging to record this type of information.