中文摘要：

以一侧全开式圆柱形腔体为研究对象，在考虑腔体内工质（空气）物性参数随温度的变化以及腔体固壁内导热与腔体内空气自然对流之间相互耦合的基础上，采用RNGk-e紊流模型对不同热流密度、腔体倾角以及3种不同壁面加热边界时腔体内的自然对流传热特性进行了三维数值模拟。3种加热边界分别为底面加热（工况Ⅱ）、侧面加热（工况Ⅱ）以及底面和侧面同时加热（工况Ⅲ）。结果表明，定热流下的圆柱形腔体内和开口面的温度和速度分布、腔体内壁平均温度、底面与侧面的平均温差、腔体内壁的平均努赛尔特数等自然对流传热特性不仅受到热流密度和腔体倾角的影响，还受到腔体壁面加热边界的影响，如只有底面加热的工况I与存在侧面加热的工况II和Ⅲ相比，前者自然对流传热特性相差较大。

英文摘要：

By adopting renormalization group （RNG） k-e turbulent model, a three dimensional numerical investigation, which considers the variable thermo-physical properties and the coupling between the thermal conduction in the cavity wall and the natural convection of the air flow inside the cavity, was performed to study the characteristics of natural convection in fully opened cylindrical cavity. Three cases with different heating boundary conditions were examined： （I） a case with only bottom wall surface heated and side wall surface insulated, （II） a case with only side wall surface heated and bottom wall surface insulated, and （Ill） a case with bottom and side wall surfaces heated. The heated walls were maintained at constant heat flux. It was concluded that not only the wall heat flux and tilt angle of cavity are factors that strongly affect the temperature and velocity contours inside the cavity and in the opening surface, the mean temperature difference between bottom and side wall surfaces, the mean Nusselt number inside the cavity, etc. , but also the wall heating boundary condition does. Furthermore, the natural convection for case I with only bottom wall heated has a great distinctive, in comparison with the case II and III both considered with side wall surfaces heated.