底部离散加热、顶部冷却的二维空腔内高宽比对自然对流的影响

The Effect of Aspect Ratio on Natural Convection in a Cavity with Discrete Heaters at the Bottom and a Top Heat Sink

对底部均匀分布５个离散平面热源，顶部等温冷却的二维封闭空腔内高宽比对高Ｐｒ数介质层流自然对流的影响进行了数值分析。空腔高宽比范围为０．０８≤Ａ＜０．３３３．Ｒαｗ为１０７，Ｐｒ取作９０．高宽比极小时半侧空腔内形成５个被零流线分隔的环状流，随着高宽比的增加逐渐汇聚为单一的一次流，且流速增加。研究范围内冷源平均努谢尔特数Ｎｕｃ在Ａ＝０．１３６时达最小值。之后有所上升，在Ａ＝０．１６４达一极值。当Ａ继续增大时，Ｎｕｃ之值由于流体速度增长的快慢而上下波动。

Numerical study is performed to analyse the influence of aspect ratio on the nat-ural convection of high Pr fluid in a cavity with five discrete heaters at the bottom and an isothermalheat snk at the top,The range of aspect ratio is from 0.082 to 0.333, Raw is 107 and Pr is 90.Inthe half of the eavity five independent flow cells seperated by zero stream lines can be observed atsmall aspect ratio,which gradually merge into a single flow when aspect ratio increases and finallybeeome a big cell at A = 0.333.The average nusselt number based on the cooling arca,Nuc,showsthe highest value at A=0.082.With the incrcase of A,Nuc decreases and arrives the lowest valuewhile A=0.138,then increases and reaches an extreme value as A=0.164.After that Nuc fluctu-ates with the variation of increasing rate of flow velocity.