Abstract
This experiment measured the instantaneous temperature and velocity field synchronously in non-isothermal turbulent boundary layer in a rotating straight channel with a parallel-array hot-wire probe. The Reynolds number based on the bulk mean velocity (U) and hydraulic diameter (D) is 19000, and the rotation numbers are 0, 0.07, 0.14, 0.21 and 0.28. The mean velocity u and mean temperature T as well as their fluctuating quantity u’ and T’ were measured at three streamwise locations (x/D = 4.06, 5.31, 6.56). A method for temperature-changing calibration with constant temperature hot-wire anemometers was proposed. It achieved the calibration in operational temperature range (15.5 °C–50 °C) of the hot-wire via a home-made heating section. The measurement system can obtain the velocity and temperature in a non-isothermal turbulent boundary layer at rotating conditions. The result analysis mainly contains the dimensionless mean temperature, temperature fluctuation as well as its skewness and flatness and streamwise turbulent heat flux. For the trailing side, the rotation effect is more obvious, and makes the dimensionless temperature profiles lower than that under static conditions. The dimensionless streamwise heat flux shows a linear decrease trend in the boundary layer. It is hoped that this research can improve our understanding of the flow and heat transfer mechanism in the internal cooling passages of turbine rotor blades.
Highlights
Limited by technical difficulties under rotating and heating conditions, most of the experimental investigations could only measure flow field or heat transfer separately
Koyama et al.[3] studied the influence of the Coriolis force on the developing turbulent boundary layer in a rotating channel with hot-wire. He found that the secondary flow caused by the Coriolis force would make the leading side more stable and the trailing side less stable
The research showed that the cross flow velocity and the longitudinal vorticity were linearly proportional to the rotation number
Summary
Limited by technical difficulties under rotating and heating conditions, most of the experimental investigations could only measure flow field or heat transfer separately. Koyama et al.[3] studied the influence of the Coriolis force on the developing turbulent boundary layer in a rotating channel with hot-wire. The experimental results showed that under three different thermal boundary conditions, the heat transfer of the ribbed U channel was the worst when the same temperature was maintained on the four surfaces.
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