辐射侧加热腔内自然对流传热特性研究

Research on Heat Transfer Characteristics of Natural Convection in a Radiatively Side-heated Cavity

为了明确辐射侧加热封闭方腔内半透明流体的自然对流传热现象及规律,采用有限体积法进行数值模拟研究,分析了瑞利数和光学厚度对流场、温度场以及传热特性的影响。结果表明:与传统侧壁加热腔内自然对流相比,辐射侧加热腔内等温线和流场分布规律不一致;随着瑞利数和光学厚度增加,涡心由中心位置沿直线向辐射入射侧斜上方偏移;随着瑞利数增加,等温线变得更均匀;随着光学厚度增加,等温线变密,努塞尔数Nu与瑞利数Ra_T的标度律指数减小,当光学厚度增加到一定时标度律不再变化,此时传热标度律与传统恒壁温侧加热腔内自然对流相当,满足Nu~Ra_(T)^(0.29)。

To clarify the heat transfer phenomenon and law of natural convection of semi-transparent fluid in a closed radiatively side-heated cavity,the finite volume method was adopted to analyze the effects of Rayleigh number and optical thickness on flow field,temperature field and heat transfer characteristics.The results show that the isotherm is not consistent with flow field distribution law in a radiatively side-heated cavity compared with the conventional natural convection in a side wall heated cavity;with the increase of Rayleigh number and optical thickness,the position of the eddy center shifts from the center to the inclined top of the radiation incident side wall along straignt line;with the increase of Rayleigh number,the isotherms become more uniform;with the increase of optical thickness,the isotherms become denser,the scaling law indexes of the Nusselt number Nu and Rayleigh number Ra_T decrease;when the optical thickness increases to a certain value,the scaling law nearly does not changes,at that time,the heat transfer scaling law is equivalent to the natural convection in a conventional side heated cavity under constant wall temperature,which meets Nu~Ra_(T)^(0.29).