Abstract
The torque in the Taylor-Couette flow for radius ratios , with smooth or grooved wall static outer cylinders, is studied experimentally, with the Reynolds number of the inner cylinder reaching up to , corresponding to the Taylor number up to . The grooves are perpendicular to the mean flow, and similar to the structure of a submersible motor stator. It is found that the dimensionless torque , at a given and , is significantly greater for grooved cases than smooth cases. We compare our experimental torques for the smooth cases to the fit proposed by Wendt [F. Wendt, Ing.-Arch. 4, 577 (1993)] and the fit proposed by Bilgen and Boulos [E. Bilgen and R. Boulos, J Fluids Eng. 95, 122 (1973)], which shows both fits are outside their range for small gaps. Furthermore, an additional dimensionless torque (angular velocity flux) in the smooth cases exhibits an effective scaling of in the ultimate regime, which occurs at a lower Taylor number, , than the well-explored case (at ). The same effective scaling exponent, 0.39, is also evident in the grooved cases, but for and 0.985, there is a peak before this exponent appears.
- Received 3 December 2017
- Revised 31 January 2018
DOI:https://doi.org/10.1103/PhysRevE.97.033110
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