Streamlines can be visualised in steady flow in the wind tunnel by using fog, smoke or tufts. In this way, a clear impression of an instantaneous flow field flow can be taught and problematic flow areas, such as stall, can be shown.  
  The HM 225.08 experimental unit - used in the HM 225 Aerodynamics Trainer - allows the streamlines to be visualised using fog. In the fog generator supplied a fog fluid is evaporated and inlet into the wind tunnel via a slotted pipe. A model (aerofoil, cylinder, orifice plate) is located in the measurement section, around and through which the fog flows. The flow course for the flow around and through becomes visible, as does flow separation.
  The measurement section has a black background and a transparent front plate for better observation of the streamlines. The aerofoil model's angle of attack is adjustable. The fog fluid is non-toxic, water soluble and the precipitate does not affect common materials. Precipitates can be easily wiped off with a cloth.
  The experimental unit is attached to the air outlet of the HM 225 trainer, simply and precisely with quick release fasteners.
  The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.

- illustrative demonstration without detection or

  analysis of measured values
- flow patterns in real fluids when flowing around

  and through models
  * aerofoil with adjustable angle of attack
  * cylinder
  * orifice plate for change in cross section
- flow separation and stall