Experimental study on turbulent thermal convection = 난류 열 대류 현상의 실험 연구

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Experiments have been conducted to investigate mean thermal structure in unstable turbulent thermal convection between two horizontal flat plates. The upper plate was kept at a constant cold temperature and the bottom plate at a constant hot temperature. Both air and water were used as its working fluid. Chamber aspect ratios were 3.08 and 6.17, the mean temperature difference between two plates were 0.9-7.9℃, which gave us Rayleigh number in a range $6.13×10^5$-$1.25×10^8$. The heat transfer correlation found through the experiments are $Nu=0.139R_a^0.285$ for air and $Nu=0.087R_a^0.319$ for water. Mean temperature profiles and fluctuations were obtained by using a Pt-Pt Rh thermocouple of 0.025mm diameter. The measured profiles have been differentiated to get the mean temperature gradient profiles. The results clearly identified the -2 and -4/3 power law regions which have been proposed by Kraichnan (1962) and Chung & Adrian (1981). The buoyancy defect region proposed by Chung et. al. was not detected, and the defect region for water was detected possibly due to slight unsteadiness of the convective motion. It was found that a correlation formula for mean temperature of Chung et. al. is in good agreement with this experimental data.
Advisors
Chung, Myung-Kyoonresearcher정명균researcher
Description
한국과학기술원 : 기계공학과,
Publisher
한국과학기술원
Issue Date
1981
Identifier
63118/325007 / 000791172
Language
eng
Description

학위논문(석사) - 한국과학기술원 : 기계공학과, 1981.2, [ [vi], 58, [1] p. ]

URI
http://hdl.handle.net/10203/47088
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=63118&flag=dissertation
Appears in Collection
ME-Theses_Master(석사논문)
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