Fabrication and characterization of a turbulent channel flow facility for studying super-hydrophobic surface stability

A turbulent channel flow facility was designed, fabricated, and tested at the University of Massachusetts Dartmouth. This facility aims to study the stability of super-hydrophobic surfaces (SHS) subjected to turbulent flows. The water flow is driven by one 3-horsepower centrifugal pump. The channel has optical access from all sides and has removable windows for the installation of SHS. The channel's internal dimensions are 1016 mm × 50 mm × 6.4 mm (length × width × height). Due to the 8:1 aspect ratio of the cross-section, the flow in the channel is nearly two-dimensional. The mean flow speed in the test section varies from 0.5 to 10 m/s. The Reynolds number based on channel height and mean flow speed varies from 3200 to 64,000. In this presentation, we will describe major components of the channel flow facility, including the storage tank, settling chamber, test section, diffuser, etc. We will also discuss the skin-friction coefficient measured by pressure drop, and the profiles of mean velocity and Reynolds stresses measured by particle image velocimetry (PIV). Furthermore, we will describe the fabrication technologies of various SHSs, and two optical technologies for examining the gas layer on the SHS based on total internal reflection and reflection interference.