Example of an internal flow whose organization plays a major part in the efficiency of a turbomachine blade cascade. The visualisations were performed on a model similar to that tested in a wind tunnel and confirmed the periodicity of the flow, the existence of vortices near the side wall, and the efficacy of blowing as a means to suppress these unwanted flow separations.

Image created by Henri Werlé. Reproduced with permission from his spectacular collection Courants et Couleurs published in 1974 by ONERA, the French Aerospace Lab.