Flow visualizations and heat transfer measurements for a rotating pin-fin heat sink with a circular impinging jet |
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| Authors: | Tzer-Ming Jeng Sheng-Chung Tzeng Hong-Ru Liao |
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| Affiliation: | 1. Department of Mechanical and Aerospace Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland OH 44106, USA;2. Mechanical and Aerospace Engineering Department, University of California, Los Angeles CA 90095, USA;3. School of Mechanical Engineering, Sungkyunkwan University, 300 Cheoncheon-dong, Suwon 16419, Republic of Korea.;4. School of Mechanical Engineering, 585 Purdue Mall, West Lafayette IN 47907-2088, USA;1. Department of Chemical Engineering, Shahrood Branch, Islamic Azad University, Shahrood, Iran;2. Chemical Engineering Department, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran;3. Department of Chemistry, Shahrood Branch, Islamic Azad University, Shahrood, Iran |
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| 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 in-line arranged 5 × 5 and 9 × 9 pin-fins were employed. The side length (L) of the heat sink equaled 60 mm and was fixed. Variable parameters were the relative length 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 (Rer = 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 (Nu0) for the 9 × 9 pin-fin heat sink with L/d = 4.615 and C/d = 11. For a rotating system, a bigger Rer meant a more obvious heat transfer enhancement (NuΩ/Nu0) in the case of smaller Re, but NuΩ/Nu0 decreased with increasing Re. In this work, NuΩ/Nu0 in L/d = 2.222 is higher than in L/d = 4.615; among the systems in L/d = 2.222, bigger NuΩ/Nu0 exists in the case of C/d = 9–11, but among the systems in L/d = 4.615, bigger NuΩ/Nu0 exists in the case of C/d = 1–3. Finally, according to the base of NuΩ/Nu0 ? 1.1, the criterion of the substantial rotation was suggested to be Rer/Re ? 1.154. |
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