Systematic Research on the Characteristics of Impingement Heat Transfer in Comparatively Narrow Space

较狭窄空间冲击传热特性的系统研究

• 批准号: 62550147
• 负责人: ICHIMIYA Koichi
• 金额: $ 1.28万
• 依托单位: University of Yamanashi
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1987
• 资助国家: 日本
• 起止时间: 1987 至 1989
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-62550147/
• 关键词: Thermal Engineering; Forced Convection; Impingement Heat Transfer; Laminar Jet; Turbulent Jet; 層流・乱流噴流

The impingement flow has been increasingly utilized for enhancing the intensity of heat and mass transfer of heat transfer media. Conditions corresponding to such flows are encountered in engineering device to remove the heat from the electric device, to dry the film or the paper and to flatten the temperature distribution of high temperature steel slab. So, we should study on the beat transfer of impinging flow in the narrow space between the nozzle and the impinged surface.In the present study, we experimented and analyzed by changing the kind of the nozzle ( slit-type nozzle and the circular nozzle ), the number of the nozzles ( a single nozzle and array of the nozzles ), the distance between the nozzle and the impinged surface, the size of the impinged surface, the flow rate and the pitch of the nozzles. Additionally, numerical analysis was performed in the laminar impinging jet flow.In the first step, the effect of the size effect of a heated slab was examined numerically on the c … More haracteristics of flow situation and impingement heat transfer caused by a laminar jet. It was found that the generation of recirculating flows near the side surface of a heated slab and the upper confined plate depends on the ratio of the size of a heated slab and the nozzle width (W>l, W<1) and the spanwise variation of the local Nusselt number on the lower wall exhibits one or two maxima. In the second step, experiments were performed on the characteristics of impingement heat transfer by three slot jets. For laminar jet, experimental values were compared with numerical results. For turbulent jet, two peaks of the local Nusselt number were obtained behind the second nozzle. The position of the second peak approached the nozzle with the decrease of the space between nozzle and impinged surface. The average Nusselt number between the central and the second nozzle was determined by the ratio was determined by the ratio P/H and tile Reynolds number based on the pitch of the nozzles. In the third step, the impingement heat transfer caused by a single circular jet and four-turbulent circular jets. For a single circular jet, two peaks of the local Nusselt number were produced at R=0.5 and the position depended on Reynolds number. For four circular jets, the maximum value of mean Nusselt number was obtained at the dimensionless nozzle-impinged surface spacing H=1.5-2.These results will be applied in the practical facility as the basic data. Less

冲击流被越来越多地用于增强传热介质的传热传质强度。在工程设备中遇到与这种流动相对应的条件，以从电气设备中去除热量，干燥薄膜或纸张，并使高温钢板的温度分布平坦化。因此，有必要对喷嘴与冲击面之间的狭窄空间内冲击流的拍频传递进行研究（狭缝式喷嘴和圆形喷嘴），喷嘴数量（单个喷嘴和喷嘴阵列），喷嘴和撞击表面之间的距离，撞击表面的尺寸，流速和喷嘴的间距。此外，本文还对层流冲击射流进行了数值分析，首先，数值研究了加热板坯尺寸效应对冲击射流冲击速度的影响， ...更多信息 层流射流冲击换热特性的研究。结果表明，在加热板坯侧面和上限制板附近产生的回流取决于加热板坯尺寸与喷嘴宽度的比值（W> 1，W<1），下壁面局部Nusselt数沿展向的变化呈现一个或两个极大值。第二步，对三缝射流冲击换热特性进行了实验研究。对于层流射流，实验值与数值计算结果进行了比较。对于湍流射流，在第二个喷嘴后得到两个局部努塞尔数峰值。随着喷嘴与冲击面间距的减小，第二峰值的位置逐渐靠近喷嘴。中心喷嘴和第二喷嘴之间的平均努塞尔数由P/H比和基于喷嘴间距的雷诺数确定。第三步，研究了单股圆形射流和四股圆形湍流射流的冲击换热。对于单个圆形射流，局部努塞尔数在R=0.5处出现两个峰值，峰值位置与雷诺数有关。对于四个圆形射流，在无量纲撞击面间距H=1.5 ~ 2时，平均Nusselt数达到最大值。少

项目成果

一宮浩市: "上壁を有する衝突噴流熱伝達の特性に関する実験的研究(3-スリット・ノズルによる伝熱特性)" 日本機械学会論文集B編. 55. 3210-3215 (1989)

Koichi Ichinomiya：“上壁冲击射流传热特性的实验研究（使用 3 缝喷嘴的传热特性）”日本机械工程学会会刊，B 版 55. 3210-3215（1989 年）。

一宮浩市: "衝突噴流熱伝達に及ぼす加熱片寸法の影響" 日本機械学会論文集B編. 54. 142 (1988)

Koichi Ichinomiya：“加热板尺寸对冲击射流传热的影响”，日本机械工程师学会会刊，B 版，54. 142 (1988)。