权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Large Eddy effect on Turbulent Heat Transfer Analyzed by Correlations between Heat flux and Velocity Fluctuations

热通量与速度脉动相关性分析湍流传热的大涡效应

基本信息

批准号：
63460096
负责人：
HIJIKATA Kunio
金额：
$ 2.82万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-63460096/
关键词：
Turbulent Heat Transfer Corr elation between Heat Flux and Velocity Fluctuations Impinging Jet 微細熱流束計

项目摘要

Many researches to clarify the mechanism of turbulent heat transfer performance have been carried out.In the most of these researches, the relations between the turblent motions in space and the transported flux have not been studied. In this research, the structures of large eddy motion in the impinging jet, which strongly affect the heat transfer, the mass transfer and the shear stress on the impinged plate, were investigated by measuring the cross-correlations between the transported fluxes and the velocity fluctuation in the jet. The movement and collapse of the large eddies can be traced from the time and space distributions of the cross-correlation. In the case of heat transfer, the velocity field were measured by LDV, and the heat flux on the plate were measured by a hand-made heat flux sensor. To measure the shear stress and the mass transfer coefficient, electro-chemical method were used. The large eddies affecting on the heat flux moved in jet whose moving speed was quite same as the mean velocity of the jet. However, in the case of mass transfer, the auto-correlative structure was existed near the measuring point of the mass flux. This structure was caused by the existence of the diffusion boundary. In order to clarify the structure, the responses of the mass flux, the heat flux and the shear stress boundary layeto the velocity fluctuation outside of the boundary layer were numerically analyzed. The theoretical results showed that the existence of the auto-correlative structure only for the mass transfer. This tendency accurately agreed with the experunental results.

对于湍流换热性能的机理，人们进行了大量的研究，但大多数研究都没有涉及到空间湍流运动与输运通量之间的关系。本文通过测量冲击射流中的输运通量与速度脉动之间的相关性，研究了冲击射流中大涡运动的结构对冲击板上的传热、传质和剪切应力的影响。从互相关的时空分布可以追踪到大涡的运动和溃灭。在传热方面，采用激光多普勒测速仪测量速度场，用自制的热流传感器测量板上的热流密度。采用电化学方法测定了剪切应力和传质系数。影响热流密度的大涡在射流中运动，其运动速度与射流平均速度相当。而在传质情况下，在质量流量测量点附近存在自相关结构。这种结构是由于扩散边界的存在造成的。为了弄清这一结构，数值分析了边界层外的质量通量、热流和切应力对速度脉动的响应。理论计算结果表明，自相关结构只存在于传质过程中。这一趋势与实验结果完全一致。