流向电磁力作用下圆柱绕流对流换热的特性研究

摘要

Previous studies have been carried out mainly from the viewpoint of heat transfer and flow velocity,and few studies focused on the convective heat transfer efficiency.The convective heat transfer characteristics of a circular cylinder under the action of electromagnetic force was numerically studied with the finite element method based on the energy equation of convection heat transfer and basic governing equations of electromagnetic fluid control.The results show that the heat transfer power increases with the increasing of the electromagnetic force when 0＜N≤0.8,where N is an action parameter.When 0.8＜N≤1.8,the heat transfer power decreases with the increasing of the electromagnetic force.When N＞1.8,the heat transfer power increases with the increasing of the electromagnetic force.By analyzing the flow of the fluid,it' s found that the variation of the convective heat transfer power is due to the continuous sinking of the separation point.As the electromagnetic force gradually increases and the fluid velocity around the cylinder increases,the vortex street will gradually be inhibited and the separation point will continue to sink.%以往对对流换热的研究主要从传热学和来流速度角度进行,鲜有对电磁力作用下圆柱绕流对流换热效率进行的研究,而这些研究恰恰关系到对流传热效率的提高.基于对流换热的能量方程和电磁流体控制的基本控制方程,利用有限元法对电磁力控制绕流圆柱对流换热特性进行了数值分析.研究结果表明:在圆柱周围施加流向电磁力后,流向电磁力的作用参数0＜N≤0.8时,传热功率随电磁力增大而增大;当0.8＜N≤1.8时,传热功率随着电磁力增大而变小;N＞1.8时,传热功率随电磁力增大不断变大.通过分析流体的流动情况,发现产生这种结果是由于随着电磁力增大,圆柱周围流体流速增大的同时,涡街逐渐被抑制,分离点不断后移,致使对流换热功率出现这样的变化规律.