A large test section low-speed water tunnel in a small package

A novel type of low-speed water tunnel has been designed which uses an array of submersible electric thrusters to propel water through a test section centered within a large rectangular tank. This design can operate as a suction or blowdown tunnel to alternately create uniform, low-turbulence flow or spatially and temporally varying flows such as shear layers, wakes, and gusts. The thruster array architecture also enables an order of magnitude improvement in tunnel footprint for a given test section size, eschewing the need for bulky traditional elements such as the contraction, turning, and settling chambers. Planar digital particle image velocimetry (DPIV) and single-component constant temperature anemometry (CTA) measurements of flow uniformity and turbulence intensity indicate comparable flow quality to larger traditional tunnels when operated in suction mode. Dye visualizations of low Reynolds number cylinder wake flows are also presented to demonstrate tunnel capabilities.