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15 mins
Experimental study of surface modification in a fully turbulent Taylor-Couette flow
Arnoud Greidanus, Rene Delfos, Sedat Tokgoz, Jerry Westerweel
Session: Control 3
Session starts: Wednesday 26 August, 10:30
Presentation starts: 11:30
Room: Room D

Arnoud Greidanus (TU Delft)
Rene Delfos (TU Delft)
Sedat Tokgoz ()
Jerry Westerweel (TU Delft)

Friction measurements were performed in a Taylor-Couette setup. Drag reduction was obtained with a riblet surface and indicated a drag reduction for a wide range of shear Reynolds numbers, with a maximum of 5.3% at Re_s=47000 (s+=14). Tomographic PIV verified that the friction coefficients are strongly related to the flow regimes and structures. The bulk fluid rotation was changed by the application of the riblets, as the wall-bounded flow conditions at the inner cylinder wall were changed due to the surface modification and is called the rotation effect. A simple model was used to indicate the averaged bulk velocity shift (1.4%), after which the drag changes due to the rotation effect (-1.9%) and the riblet effect (-3.4%) were determined. The bulk velocity shift of 1.4% was verified by PIV measurements. Compliant surfaces will be further investigated to check their required conditions for drag reduction of wall-bounded flows