On Directional Sensivity of Thermo-Anemometer Split-Fiber Probes

0533372 - ÚT 2023 RIV FR eng C - Konferenční příspěvek (zahraniční konf.)
Lepičovský, Jan
On Directional Sensivity of Thermo-Anemometer Split-Fiber Probes.
E3S Web of Conferences. Cedex A: EDP Sciences, 2022, č. článku 01010. 345. E-ISSN 2267-1242.
[Biennial Symposium on Measuring Techniques in Turbomachinery /25./. Santorini (GR), 21.09.2020-23.09.2020]
Grant CEP: GA MŠMT(CZ) LTAUSA19036
Institucionální podpora: RVO:61388998
Klíčová slova: thermoanemometry * split-fiber probe * directional sensitivity * contamination effect
Obor OECD: Applied mechanics
https://www.e3s-conferences.org/articles/e3sconf/pdf/2022/12/e3sconf_mtt2022_01010.pdf

Hot-wire thermo-anemometer probes are extremely fragile devices, and therefore they are used mostly in clean flows with neither debris nor small particles to prevent sensor destruction. Consequently, application of hot-wire probes is limited mostly to clean laboratory environments, their employment in semi-industrial research is extremely rare, and not always successful. Film probes with deposited thin metallic sensors on cylindrical fibers are more rugged and can be successfully employed for research tasks in semiindustrial applications. Surprisingly the potentials of these probes are not yet fully utilized. Detailed investigation of direction characteristics of a splitfiber probe was carried out during the course of this work. Several interesting outcomes resulted from this study. First, it has been shown that the splitfiber probe direction sensitivity rises with the increasing velocity contrary to the decrease of the velocity sensitivity, which is a common hindrance to application of single-sensor thermo-probes to highspeed and transonic flows. Second, the analysis of the acquired data indicates that the transition of the laminar vortex street into the turbulent one occurs in the probe wake at Reynolds number values between 900 and 1000, which is markedly higher than the usually reported range between 150 and 300 for a cylinder in cross-flow. Finally, the resilience of split-fiber probes to impairment by in-flow debris has been demonstrated proving the probe ability for effective use of these probes in semi-industrial or even industrial research tasks.

Trvalý link: http://hdl.handle.net/11104/0315382