Number：

01097007

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Name：

曾憲中(Sheng-Chung Tzeng)

Titles：

Professor

Author：

Tzer-Ming Jeng , Sheng-Chung , Hong-Ru Liao

Paper name：

and heat transfer measurements for a rotating pin-fin heat sink with a circular impinging jet

Name of activity：

                  Internation Communications in Heat and Mass Transfer

Keywords：Heat transfer, Jet impingement, rotating heat sink Smoke Visualization

Abstract：

This work experimentally investigated the fluid flow and heat transfer behaviors of jet impingement onto the rotating heat sink. Air was used as impinging coolant, while the square heat sinks with uniformly inline arranged

5 x 5 and 9 x 9 pin-fins were employed. The side length (L) of the heat sink (L/d = 2.222 and 4.615), the relative distance of nozzle-to-fin tip (C/d = 0-11), the jet Reynolds number (Re = 5019-25,096) and the rotational Reynolds number (Re_f = 0-8114). Both flow characteristics of stationary and rotating systems were illustrated by the smoke visualization. Besides, the results of heat transfer indicate that, for a stationary system with a given air flow rate, there was a larger average Nusselt number (Nu_o)for the 9 x 9 pin-fin heat sink with L/d 4.615 and C/d 11. For a rotating system, a bigger Re_f meant a more obvious heat transfer enhancement (Nu_Ω/Nu_o) in the case of smaller Re, but Nu_Ω/Nu_o decreased with increasing Re. In this work, Nu_Ω/Nu_o in L/d = 2.222 is higher than in L/d = 4.615 ; among the systems in L/d 2.222, bigger Nu_Ω/Nu_o exists in the case of C/d = 9-11, but among the systems in L/d = 4.615, bigger Nu_Ω/Nu_o exists in the case of C/d = 1-3. Finally, according to the base of Nu_Ω/Nu_o ≧ 1.1, the criterion of the substantial rotation was suggested to be Re_r/Re ≧ 1.154.

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