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.

Acoustic backscatter inversion for suspended sediment concentration and size: A new approach using statistical inverse theory

“…The jet itself is a recirculating system operated by a centrifugal pump. For the present experiments, the average jet centerline velocity was 53-56 cm/s, at the vertical position where all measurements were collected, as measured by a Vectrino II instrument (Zedel and Hay, 2011). Degassed mains fresh water was used, at room temperature 21-22°C.…”

Bias in mean velocities and noise in variances and covariances measured using a multistatic acoustic profiler: the Nortek Vectrino Profiler

“…In addition, they unexpectedly 56 found non-zero mean lateral velocities, which also did not overlap between neighbouring 57 profiles. Zedel and Hay (2011) suggested that calibration problems were the cause of these 58 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 that contaminates the variances. They attributed this to Doppler noise and showed that the noise 77 affecting the two orthogonal systems of receivers is not equal.…”

Two-dimensional integral turbulent scales in compression wave in a canal

“…The measurement technology is based upon coherent Doppler processing (ZEDEL and HAY 2011). There are however known issues with the Vectrino II Profiler, including inaccurate estimation of time-averaged velocity at certain positions and wrong estimation of velocity variances at the profile "weak spots" (CRAIG et al 2011, ZEDEL and HAY 2011, DILLING and MACVICAR 2017. In the present study, both Profilers were configured to quasi-simultaneously sample the velocity at 100 Hz for 35 sampling points in a 35 mm profile (Fig.…”

“…The Vectrino II Profiler is a highresolution acoustic Doppler velocimeter used to measure three-dimensional water velocity (Nortek 2012). The measurement technology is based upon coherent Doppler processing (ZEDEL and HAY 2011). There are however known issues with the Vectrino II Profiler, including inaccurate estimation of time-averaged velocity at certain positions and wrong estimation of velocity variances at the profile "weak spots" (CRAIG et al 2011, ZEDEL and HAY 2011, DILLING and MACVICAR 2017.…”

“…In the present study, the two sampling profiles of Vectrino II Profilers were intersected about their respective "sweet spots". The "sweet spots" were locations where the signal quality was the best and corresponded to the one third to one half of the sampling profile, usually the 10 th to 20 th points (CRAIG et al 2011, ZEDEL and HAY 2011, MACVICAR et al 2014, DILLING and MACVICAR 2017. While cross-correlation calculations were performed for all points throughout the sampling volume, it is acknowledged that the signals near the two ends of the sampling profiles were of poor quality, and may yield low to zero correlation.…”