The method of tufts is the oldest one in experimental aerodynamics. Its essence is that a great number of silk threads (mini-tufts) are glued down on the model surface. They are oriented in flow along the velocity vector and in flow separation zones they deviate off the surface and vibrate.
Application of luminescent mini-tufts allows increasing significantly their contrast and, consequently, reduce their size. Such mini-tufts have a smaller perturbation effect on the flow over the model and the visualization obtained with them is more reliable. The short length of mini-tufts also makes it possible to glue them more compactly and thus to obtain a higher spatial resolution of the flow pattern. The contrast of luminescent mini-tufts is of such a degree that they may be used even on unpainted metal models.
Due to small diameter of luminescent mini-tufts the influence of centrifugal forces on the position of a mini-tuft is lessened, thereby grater possibilities to research the rotating models flow over are given.
- Mini-tufts length — 6…20 mm.
- Thickness — 20…50 μm.
- The pasting step is to be not less than the mini-tufts length (to prevent tangling).
- The tufts may be used at all flow regimes.
- Mini-tufts may be reused after been glued on the surface under research.
- The use of luminescence allows avoiding the light reflected from the model surface, the flares and the loss of useful information.
Visualization of gas flow on the model surface in wind tunnels at subsonic, transonic and supersonic velocities and in flight tests as well.