RESEARCH OF HEAT TRANSFER FROM A ROTATING CYLINDER WITH AND WITHOUT CROSS FLOW AT THE LOW REYNOLDS NUMBER

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The local and average coefficients of heat transfer from a rotating cylinder in a uniform flow were measured by Mach-Zehnder interferometer with visual observation of flow patterns. The experiments covered the range of rotating and cross-flow Teynolds numberes from 0 to 3000. The experimental study were concerned with heat transfer where the cross flow, rotation flow, and the free-convection flow were mixed. The following results were obtained. (1) At a cross-flow Reynolds number above 1000, the heat transfer was not influenced by free convection. (2) When the cross-flow Reynolds number was above 1000 and above the rotating reynolds number, the average Nusselt number agreed with the value for the static cylinder in forced comvection. (3) At a rotating Reynolds number Re _r more than twice the cross-flow Reynolds number Re _d, the average Nusselt number agreed with the equation, Nu M =0.055Re _r^<0.7>(1+8Gr_d/Re_r^2)^<0.35>. (4) At Re_d under 1000, the heat transfer was the poorest when Re _r was wtice that of Re _d.