Experimental Studies of Flows over Structured Surfaces

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Experimental Studies of Flows over Structured Surfaces

Experimental investigations focus on the study of the influence of surface morphology on friction drag. Two different approaches are made to attain drag reduction by the use of micro grooves surface structures:

  1. The influence on laminar-turbulent transition and
  2. The influence on the wall friction in fully turbulent flow state.

In the experiments for different flow velocities and accordingly Reynolds numbers following geometric parameters are determined: The shape of grooved structures (fig. 1), the diameters and the arrangement of the structures.

Fig. 1: Different shapes of the micro grooves
Fig. 1: Different shapes of the micro grooves

Therefore the test facility shown in fig. 2 has been built, consisting of the our research group`s wind tunnel “Emmy” and a special test section for generating 2D-channel flows, that is connected to the wind tunnel. This allows to arrange parameter studies comparable to the numerical investigations.

Fig. 2: Emmy Noether Research Group`s windtunnel “Emmy”. The test section exhibits micro scale structures on top and bottom walls (For illustration structures are drawn to a larger scale).
Fig. 2: Emmy Noether Research Group`s windtunnel “Emmy”. The test section exhibits micro scale structures on top and bottom walls (For illustration structures are drawn to a larger scale).