Taylor–Couette research: Twente Turbulent Taylor-Couette (T³C) and Boiling Twente Taylor-Couette (BBTC)

Skin drag reduction in the naval transport, being the largest carrier of freight in the world, is of large environmental importance as this diminishes the fuel consumption. The practical concept is to create air lubrication alongside the hull of the ship, by injecting bubbles into the boundary layer. Several laboratory experiments easily result in drag reductions of 20% and above. However, application on real life ships barely results in 5%. A solid understanding of the bubble mechanism leading to drag reduction is still missing.

To investigate the mechanism behind bubbly skin drag reduction, our group has designed a state-of-the-art turbulent two-phase Taylor-Couette setup. Two independently rotating cylinders, with a fluid in between the gap, comprise a closed and energy balanced system. At constant angular rotation rates and constant fluid temperature, one only has to measure the torque that the fluid exerts onto the cylinder’s wall to get to the drag coefficient. The inner cylinder senses this drag by means of load cells imbedded into the setup. Microbubbles and millimeter sized bubbles can be injected into the setup.

The T3C is fitted with several sensors providing global information, such as angular rotation rates, fluid temperature, torque on the inner cylinder wall and bulk gas volume fraction. In addition, there are also sensors to provide local information, such as flush mounted hot-film probes for retrieving the wall shear stress, phase-sensitive hot-film probes providing power spectra, and single or quadruple optical fiber probes to probe the bubble distribution and bubble deformation.

The flow inside the T3C setup is optically accessible through its clear acrylic outer cylinder, allowing for measurement techniques such as 3D Particle Tracking Velocimetry, 3D Particle Image Velocimetry, and laser Doppler Anemometry.

Besides two-phase flows we are also interested in single-phase turbulence. Many questions remain open regarding the features of highly turbulent flows. We aim to describe the fundamental properties of turbulent flows.

Below a video of the apparatus spinning up its outer cylinder:

Below a photo of the Boiling Twente Taylor–Couette facility doing particle tracking velocimetry using 8 high speed cameras:

PTV in BTTC

We are interested in a wide variety of problems:

Drag reduction by air injection with membranes and superhydrophobic surfaces
Effects of roughness on drag
Effects of water quality on drag reduction (salts and surfactants)
Emulsions and their phase inversion
Particles in turbulence
Mass transfer
Keplerian flow
Fundamentals of turbulent flows
…

Info:

Researchers: Timothy Chan, Luuk Blaauw, Yoan Lee, Pim Bullee, Chao Sun, Sander Huisman, Detlef Lohse.
Technical staff: Gert-Wim Bruggert, Martin Bos, and numerous of people of TCO.
Collaborators: Daniel P. Lathrop (University of Maryland), Eelco van Rietbergen (Spaarnwater)
Embedding: MESA+, JMBC, European Research Network on Turbulence, ICTR International Collaboration for Turbulence Research.
Sponsors: European Research Network on Turbulence, STW, NWO, ERC
Previous researchers: Ruben Verschoof, Rodrigo Ezeta, Dennis Bakhuis, Roeland van der Veen, Dennis van Gils, Tim Jannink, Daniela Narezo Guzmán, Peter Dung, Michael Tang