エンチュウ ハイメン ノ デンネツ リュウドウ トクセイ ( シュリュウ ミダレ ノ スケール ト エンチュウケイ ノ エイキョウ )

An experimental study was conducted on heat transfer from slightly heated circular cylinders in cross flow. Emphasis was placed on the combined influence of the scale of free-stream turbulence and the diameter of the cylinder on the rate of heat transfer at the rear stagnation point. By using a hot-wire anemometer, spectrum analysis of the anemometer signal with a Fourier analyzer is employed to investigate the separated shear layer formed behind the circular cylinder. The Nusselt number at the rear stagnation point varies with the scale ratio of turbulence and cylinder diameter, although the Reynolds number is the same. Corresponding streamwise profile of the separated shear layer is also influenced. The laminar-to-turbulent transition region moves in the streamwise direction because of a variation of the scale ratio. It was discovered that the heat transfer characteristics behind cylinders are affected by the scale ratio, and are closely related to the streamwise movement of the region of transition to turbulence in the separated shear layer