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Fluid Flow and Heat Transfer of Mixed Convection and Its Application to Thin Film Formation by CVD

混合对流流体流动和传热及其在CVD薄膜形成中的应用

基本信息

批准号：
18560198
负责人：
KITAMURA Kenzo
金额：
$ 2.37万
依托单位：
Toyohashi University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18560198/
关键词：
Heat Transfer Convective Heat Transfer Mixed Convection Forced Convection Natural Convection Upward-Facing Plate Stagnation Flow Buoyancy Effect

项目摘要

Fluid flow and heat transfer of mixed convection over upward-facing horizontal heated plates placed in a uniform downward flow of forced convection were investigated experimentally. The experiments were carried out with air and with the test plates of 50 and 100mm wide, which were heated with uniform heat flux. The Reynolds and modified Rayleigh numbers ranged as: Rew =37-2000 and Raw^*=6.2x10^4-5.3x×10^7.The flow fields over heated plates were visualized with smoke. The results showed that the laminar wedge flow from the center to the edges of the plate appears when the heat fluxes are small, while that the flow turns its direction from the edges to the center with increasing the heat flux, and, finally, the flow detaches from the center of the plate as a buoyant plume when the heat fluxes are high enough. The local heat transfer coefficients from the plates were also measured. The results showed that the coefficients under the fixed velocity of the forced flow are increased monotonously with the heat fluxes. It was also found that the overall Nusselt numbers of the plates, Nun, were predicted well with the non-dimensional parameter, (GrW^*/d/Num Rew^2.5), where Grw^* stands for the Grashof numbers. Moreover, the parameter well classify the regions of the forced, mixed and natural convection, and the mixed convection region is determined as : 0.3< (Grw^*/Num Rew^<2.5>) <15

实验研究了水平加热平板在均匀向下强制对流中的混合对流流动与换热特性。实验用空气和50和100 mm宽的试验板进行，这些试验板以均匀的热流加热。雷诺数和修正瑞利数的范围为：Rew =37-2000，Raw^*= 6.2 × 10^4 - 5.3 × 10^7。结果表明，当热流密度较小时，平板表面出现从中心到边缘的楔形层流流动，当热流密度较大时，流动方向由边缘转向中心，最终以浮力羽流的形式脱离平板中心。还测量了板的局部传热系数。结果表明，在一定流速下，对流换热系数随热流密度的增加而单调增加。我们还发现，用无量纲参数（Grw^*/d/μ Rew ^2.5）可以很好地预测平板的总努塞尔数Nun，其中Grw^* 代表格拉肖夫数。此外，该参数很好地区分了强迫对流、混合对流和自然对流的区域，确定了混合对流区域为：0.3<（Grw^*/Rew^<2.5>）<15