Research on the Enhancement of Heat/Mass Transfer due to Periodical Impingement of Eddies

涡流周期性冲击增强传热/传质的研究

• 批准号: 62550699
• 负责人: KATAOKA Kunio
• 金额: $ 1.09万
• 依托单位: Kobe University
• 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 1988
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-62550699/
• 关键词: Large-scale Turbulent Eddy; Impinging Jet Heat Transfer; Heat Transfer Enhancement; Surface Renewal Model; Coherent Turbulent Structure; 淀み線伝熱係数; 非定常渦流; 界面更新; 衝突噴流; 復復動ロール渦; 物質移動促進; 乱流伝熱

The objective of this project is to elucidate the mechanism for enhancement of the heat/mass transfer in impinging flows and to obtain a physical model useful for the development of heat transfer augmentation technology. The effect of large-scale turbulent eddies on heat transfer enhancement was experimentally studied in both axisymmetric and two-dimensional jets.It has been found that the heat/mass transfer in impinging jets is unsteady in nature and that the mechanism for enhancement is controlled by the surface renewal effect of large-scale turbulent eddies impinging quasi-periodically on heat transfer surfaces. It has been found that not only the arrival velocity and its turbulence intensity (velocity scale) but also the characteristic frequency (time scale) are predominant parameters. The characteristic frequency for surface renewal effect was determined by a statistical analysis with conditional sampling applied to time-traces of arrival velocity.Based on these results, the second-phase investigation was also made on the enhancement effect of cylindrical obstacles inserted into approaching jet streams. It has been found that it is possible at short nozzle-to-plate distances to enhance the jet impingement heat transfer and to control its distribution by making use of the wake flows behind cylinders which produce effectively large-scale turbulent eddies.

本计画的目的在于阐明撞击流强化热质传递的机制，并获得一个有助于发展强化热质传递技术的物理模型。通过实验研究了轴对称和二维射流中大尺度湍流涡旋对强化传热的影响，发现撞击射流中的传热/传质本质上是不稳定的，其强化机理受控于大尺度湍流涡旋准周期性撞击传热表面的表面更新效应。结果表明，不仅到达速度及其湍流强度（速度尺度），而且特征频率（时间尺度）是主要参数。通过对到达速度时间轨迹的条件抽样统计分析，确定了表面更新效应的特征频率，并在此基础上，对近场射流中插入圆柱形障碍物的增强效应进行了第二阶段的研究。已经发现，在短的壁面距离下，可以通过利用柱后的尾流来增强射流冲击传热并控制其分布，该尾流有效地产生大尺度湍流涡流。

项目成果

Kataoka, K.; Ase, H.; Sako, N.: "Unsteady Aspects of Large-scale Coherent Structures and Impinge-ment Heat Transfer in Round Air Jets with and without Controlled Excitation." International Journal of Engineering Fluid Mechanics. 1. 365-382 (1988)

片冈，K.；

K. Kataoka;M. Suguro;H. Degawa;K. Maruo;I. Mihata: International Journal of Heat and Mass Transfer. 30. 559-567 (1987)

K.片冈；M.

Kataoka,K.;Okada,Y.;Morikawa,Y.;Iwata,A.: Journal of Chemical Engineering of Japan. 20. 363-368 (1987)

Kataoka,K.；Okada,Y.；Morikawa,Y.；Iwata,A.：日本化学工程学报。

Kataoka,K.;Okada,Y.;Morikawa,Y.;Iwata,A.: Jouranal of Chemical Engineering of Japan. 20. 363-368 (1987)

Kataoka,K.；Okada,Y.；Morikawa,Y.；Iwata,A.：日本化学工程学报。

Kataoka,K.;Degawa,H.;Hamada,Y.;Hamano,S.: TRANSPORT PHENOMENA IN TURBULENT FLOWS,Hemisphere(Proc.2nd Int.Symp.on Transport Phenomena in"Turbulent Flows",Tokyo,Oct.25-29,1987). 349-360 (1988)

片冈，K.；出川，H.；滨田，Y.；滨野，S.：湍流中的传输现象，半球（Proc.2nd Int.Symp.on Transport Phenomena in "Turbulent Flows"，东京，10 月 25 日-