Experimental study of surface modification in a fully turbulent Taylor-Couette flow

Conference paper (2015)

Authors

A.J. Greidanus Fluid Mechanics - Mechanical, Maritime and Materials Engineering
R. Delfos Energy Technology - Mechanical, Maritime and Materials Engineering
S. Tokgoz Fluid Mechanics - Mechanical, Maritime and Materials Engineering
J. Westerweel Fluid Mechanics - Mechanical, Maritime and Materials Engineering
Research Group
Fluid Mechanics (Mechanical, Maritime and Materials Engineering) (TU Delft)
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Published Date

2015

Language

English

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Faculty

Mechanical, Maritime and Materials Engineering

Department

Process and Energy

Research Group

Fluid Mechanics

Abstract

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 Res = 4.7 × 104 (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.