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研究了充填流体-饱和多孔介质的矩形管中,随温度变化的粘性对充分发展强迫对流的影响.采用Darcy流动模型并假设粘性-温度为倒线性关系.管壁视为均匀热通量,即Kays和Craw-ford称为的H边界条件.当流体粘性随温度升高而降低时,管壁的Nusselt数增大.求解速度和温度分布时,利用热力学第二定律求解了局部平均熵产率.根据Brinkman数、Péclet数、粘性变化数、无量纲管壁热通量和管道截面宽高比,给出了熵产率、Bejan数、传热不可逆性和流体流动不可逆性的表达式.这些表达式是该类问题参数研究的基础.可以看出,当管道截面宽高比的增大使熵产率减小时,方形管中流动产生的熵大于矩形管,这类似于Ratts和Raut研究的明流(clear flow)情况.
The effect of viscosity change with temperature on the forced convection in a rectangular tube filled with fluid-saturated porous media was investigated. The Darcy flow model was used and the viscous-temperature dependence was assumed. The tube wall was considered as a uniform heat flux, ie Kays and Crawford called H boundary conditions.When the viscosity of the fluid decreases with increasing temperature, the Nusselt number of the tube wall increases.When solving the velocity and temperature distribution, the second law of thermodynamics is used to solve the local average entropy yield The expressions of entropy yield, Bejan number, irreversibility of heat transfer and irreversibility of fluid flow are given according to Brinkman number, Péclet number, viscous change number, dimensionless wall heat flux and pipe cross section aspect ratio. The expression is the basis for the study of the parameters of this type of problem.It can be seen that when the entropy yield decreases as the aspect ratio of the pipe section increases, the entropy produced by the flow in the square pipe is larger than that of the rectangular pipe, which is similar to that of Ratts and Raut Clear flow situation.