Spatio-temporal distribution of convective heat transfer behind a backward-facing step was measured in order to explore the dynamic behavior of the heat transfer caused by flow separation and reattachment. This measurement was achieved by using a high-speed infrared thermograph which measured temperature fluctuation on a thin foil heated electrically. The attenuation due to both the thermal inertia and the lateral conduction was restored by solving heat conduction equations inside the test surface. As a result, it was clarified that the heat transfer enhancement in the flow reattaching region had a spot-like feature. Each spot spread with time and overlapped others, forming a complex feature in the spatio-temporal characteristics of the heat transfer. The characteristic spanwise wavelength of this structure was approximately 1.2 times the step height for Reynolds number of 2000 ≤ ReH ≤ 5500, regardless of the step height. The characteristic frequency of the fluctuation in the reattaching region was St = 0.04–0.08 although there was no clear periodicity. This fluctuation is likely to be related to the low-frequency unsteadiness observed in the literature.
- Heat Transfer Division
Spatio-Temporal Measurement of Convective Heat Transfer for the Separated and Reattaching Flow
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Nakamura, H. "Spatio-Temporal Measurement of Convective Heat Transfer for the Separated and Reattaching Flow." Proceedings of the 2010 14th International Heat Transfer Conference. 2010 14th International Heat Transfer Conference, Volume 4. Washington, DC, USA. August 8–13, 2010. pp. 47-55. ASME. https://doi.org/10.1115/IHTC14-22753
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