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Precise measurements of torque in von Karman swirling flow driven by a bladed disk

Mukherjee, Aryesh; Lukaschuk, Sergei; Burnishev, Yuri; Falkovich, Gregory; Steinberg, Victor

Authors

Aryesh Mukherjee

Sergei Lukaschuk

Yuri Burnishev

Gregory Falkovich

Victor Steinberg



Abstract

© 2018 Informa UK Limited, trading as Taylor & Francis Group Scrupulous measurements and detailed data analysis of the torque in a swirling turbulent flow driven by counter-rotating bladed disks reveal an apparent breaking of the law of similarity. Potentially, such breakdown could arise from several possible factors, including dependence on dimensionless numbers other than Re or velocity coupling to other fields such as temperature. However, careful redesign and calibration of the experiment showed that this unexpected result was due to background errors caused by minute misalignments which lead to a noisy and irreproducible torque signal at low rotation speeds and prevented correct background subtraction normally ascribed to frictional losses. An important lesson to be learnt is that multiple minute misalignments can nonlinearly couple to the torque signal and provide a dc offset that cannot be removed by averaging. That offset can cause the observed divergence of the friction coefficient (Formula presented.) from its constant value observed in the turbulent regime. By significant modifications of the setup and conducting the experiment with one bladed disk and precisely aligned the disk, torque meter and motor shaft, we are able to conduct precise measurements close to the expected resolution at small torques at low rotation speeds and to confirm the similarity law in a wide range of Re, in particular, in low viscosity fluids.

Citation

Mukherjee, A., Lukaschuk, S., Burnishev, Y., Falkovich, G., & Steinberg, V. (2018). Precise measurements of torque in von Karman swirling flow driven by a bladed disk. Journal of Turbulence, 19(8), 647-663. https://doi.org/10.1080/14685248.2018.1494833

Journal Article Type Article
Acceptance Date Jun 21, 2018
Online Publication Date Jul 12, 2018
Publication Date Aug 3, 2018
Deposit Date Sep 7, 2018
Publicly Available Date Mar 29, 2024
Journal Journal of Turbulence
Electronic ISSN 1468-5248
Publisher Taylor and Francis
Peer Reviewed Peer Reviewed
Volume 19
Issue 8
Pages 647-663
DOI https://doi.org/10.1080/14685248.2018.1494833
Keywords Swirling flow; Bladed disk; Precise torque measurements
Public URL https://hull-repository.worktribe.com/output/940553
Publisher URL https://www.tandfonline.com/doi/full/10.1080/14685248.2018.1494833

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