Thesis
Direct measurement of parallel plate heat sink bypass flow
Washington State University
Master of Science (MS), Washington State University
2006
Handle:
https://hdl.handle.net/2376/101864
Abstract
If not fully shrouded, forced air cooling flow has the propensity to bypass a highly restrictive flow channel such as those provided by the heat sinks frequently used in thermal management applications for electronic packages. While it is recognized that bypass decreases the cooling effectiveness of an extended surface, little effort has been made to directly measure the flow around an array to characterize bypass. For the current research, wind tunnel tests were performed where discrete spatial velocity measurements of the flow downstream of a densely-finned parallel plate heat sink were made with a constant temperature anemometer that utilized a miniature thermistor probe. The process of taking velocity measurements was automated by employing a probe positioning xy-traverse with computerized control and data acquisition. These measurements provided a high-resolution velocity survey downstream of the array. Tests were performed with an approach velocity of 4.5 m/s and the thermistor anemometer located 2 mm and 25 mm downstream of the heat sink. Upon inspection of the velocity surveys, flow mixing was evident in the 25 mm results while a clear "footprint" of the array was apparent in the 2 mm survey. The velocity measurements were reduced further by numerical integration to determine the average flow velocity exiting the array. The flow measurements from the 2 mm test provided an average velocity exiting the array of 1.6 m/sec while the 25 mm test produced an average velocity of 2.6 m/sec. The bypass ratio was determined to be 64 % for the 2 mm test and 42 % for the 25 mm test. In comparison, a two-branch model, commonly used in industry, provided a bypass ratio of 69 %. This further demonstrated flow mixing at the 25 mm location. The results of the 2 mm test and the model compared well. However, the velocity measurements at this location may have been influenced by the combination of the probe sensitivity to multi-directional flow and flow separation directly downstream of the array.
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Details
- Title
- Direct measurement of parallel plate heat sink bypass flow
- Creators
- Dean D. Crockett
- Contributors
- R. V. Westphal (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525127601842
- Language
- English
- Resource Type
- Thesis