Turbulence measurements in a jet: Comparing the vectrino and vectrinoii

Abstract

Results are reported from an experiment carried out with the newly developed Nortek VectrinoII and the standard Nortek Vectrino in a turbulent axisymmetric jet at a Reynolds number of 5000. The mechanical and acoustic characteristics of these instruments are identical. However, the electronics and signal processing scheme in the VectrinoII represent advancements over those in the original Vectrino (referred to as VectrinoI in this paper). In addition, the VectrinoII provides for profiling over a ca. 3 cm range interval thereby allowing direct measurement of the spatial structure of the flow. The two instruments deliver comparable performance as measured by mean velocity profiles, turbulent kinetic energy spectra, and the derived values of Reynolds stress and dissipation. The Vectrino measurements are compared to the mean and turbulent properties observed by [1] using hot-film and Laser Doppler anemometry. Here, there is good agreement in mean velocity and Reynolds stress measurements. Significant differences are seen in dissipations and velocity variance.