A viscous coating can be used to visualize the current lines on the surface of a model surrounded by a flow. These lines are also called friction lines.
copyright © ONERA 1996-2006 - All rights reserved
Visualization of the flow at high angle of attack on the upper wing surface of a future combat aircraft configuration using colored coatings
(GMT)
The model is thus covered with a preparation of different colors, according to the effects desired, and illuminated by a UV light. The coating's composition varies with the test conditions (pressures). Under the action of the wind tunnel's airflow, the air's friction drags on the coating and reveals the separated and/or vortex flow areas. This change is recorded on video cassettes. Once the coating is set, the airflow is stopped and photographic views are taken of the assembly and the details.
This qualitative method, which is used to access the topology of the flow on the surface, may help in the understanding certain global results, such as the loads, or local results, such as the pressure measurements. Although it is very instructive, it is also very difficult to implement and can only be used in test conditions in a wind tunnel.
copyright © ONERA 1996-2006 - All rights reserved
Details of the visualization using colored coatings
(GMT)
Testing and comments: Hyacinthe Buxadéra, Testing Engineer at the Fauga-Mauzac center
