Turbulence measurements with a nano-scale thermal anemometry probe

Abstract

A nanoscale thermal anemometry probe (NSTAP) has been developed for high Reynolds number turbulence measurements. NSTAP has working principles similar to conventional hot-wire anemometry, at the same time having greatly improved spatial and temporal resolution. Fabrication of NSTAP has been conducted, using several semiconductor and MEMS (microelectromechanical system) techniques. Sensing element of NSTAP is a nano-scale wire with dimensions 100 nm x 2 micron x 60 micron or 100 nm x 300 nm x 30 microns. Measurements in grid turbulence were conducted in order to validate the performance of these new sensors. NSTAP was compared to hot-wires with wire lengths 0.5, 0.75, 1.0 and 1.5 mm. Results showed NSTAP having good agreement with conventional hot-wire sensors and demonstrated faster temporal response, as well as better spatial resolution. This marks the first time that a micro-scale velocity sensor free of end- or substrate-conduction has been constructed and successfully tested in a turbulent flow.