http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
오수철(Su-Cheol Ohu),박성수(Sung-Soo Park) 한국태양에너지학회 1993 한국태양에너지학회 논문집 Vol.13 No.1
본 硏究는 軸對稱空氣噴流界에서 흐름方向에 垂直이 되도록 設置한 平板傳熱面上에서의 熱傳達을 增進시키기 위해 空氣噴流에 旋回를 주었을때, 流動의 特性 및 傳熱面에서의 傳熱增進效果와 이에 따른 亂流强度와 關係, 그리고 旋回를 주었을때와 주지 않았을때와의 熱傳達率의 比較와 最適旋回條件 및 이에 대한 傳熱特性을 究明하기 위한 實驗的 硏究이다.<br/> 본 實驗에서는 附加的인 動力을 使用하지 않고 簡便하게 熱傳達을 增進시키기 위한 方便의 하나로, 노즐出口에 Twisted Tape이 設置된 Pipe를 附着하여 空氣噴流에 旋回를 주었으며, Twisted Tape의 비틀림 角度에 따른 流速은 旋回逃를 S=0.,0.056,0.167,0.222로 하였다. 流速은 14,20,26,32,38,44m/s 條件으로, 傳熱面間距離(H/D)는 1에서 14까지 하였고, 熱傳達增進을 일으키는 流動構造를 解析하기 위해 熱線流速計를 使用하여 旋回度에 따라 各點에서의 流速 및 亂流强度를 測定하였으며, 傳熱面의 溫度를 測定하여 Nu를 求하고 旋回를 주었을때와 주지 않았을때의 熱傳達增進效果를 比較하였따. 또한 旋回度에 따른 熱傳達이 最大가 되는 最適距離를 提示하였으며 亂流强度와 熱傳達과의 關係를 究明하였다. This Paper deals with the experimental study of the axisymmetric air jet impinging vertically on the flat heating surface with and without swirl. The purpose of this study is to investigate the characteristics of flow, augmentation of heat transfer rate, turbulent intensity, and the comparison of heat transfer rate, the optimal swirling condition about the swirl and nonswirl axisymmetric air jet. In order to augment the heat transfer on the flat heating surface without introducing any additional power, the technique used in the present work was placement of twisted tape inserted pipe in front of the nozzle exit in order to make a swirl. The effect of swirl degree is investigated in case of S = 0, 0.056, 0.111, 0.222 and the velocity of the jet was 14, 20, 26, 32, 38, 44m/ s. The distance between the nozle exit and the stagnation point on the impinging plate was the HID = 1~14. In order to analyze of the flow structure which increase heat transfer, the velocity and the turbulent intensity of the axisymmetric jet was measured by a hot wire anemometer according to the swirl number and HID.
吳壽喆,任將淳,徐正閏 慶熙大學校 1974 論文集 Vol.8 No.-
Nucleate pool boiling of water from upward-facing flat horizontal surface was experimentally studied under atmospheric pressure. A 4/0 polished bronze surface were studied from the incipient boiling heat flux of 2.88×10 exp (4) ㎉/㎡h to the maximum flux of 5.86×10 exp (5) ㎉/㎡h. Data were obtained for the populations of active site at heat flux up to 1.0×10 exp (5) ㎉/㎡h. The relation between the heat flux and the temperature difference was expressed as follows. q/A=0.5×ΔT^2.93 Experimental equation was set up by making use of Stanton number for the heat transfer coefficient and Reynolds number for the generating velocity of bubble on the surface. The heat transfer regions were found to exist in nucleate boiling, depending upon the mode of vapor generation. The vapor structures on the surface progressed through a sequence of first discrete bubbles, then vapor columns and vapor mushrooms, and finally vapor patches, as the surface temperature was increased. When the heat flux exceeded 3.6×10 exp (5) ㎉/㎡h, bubbles coalesed on the heating surface before leaving it.