大型双射流流化床的流体动力学特性

在Ф0 .5m× 8m大型双射流流化床中 ,通过摄像、放像逐帧分析法和sthVCD软件分析录像转换的VCD ,得到了不同管间距下双射流典型的运动图像 .同时研究了两射流独立存在区、过渡区和射流合并区 3种流型的相互转变 ,得出了流型转变的关系式 .不同射流管间距下相同射流气速的射流深度相比 ,管间距减小则射流深度减小 ;在较小的管间距和相对高的射流气速下 ,两射流在射流深度之内始终合并 ,表现为射流合并高度 .得出了射流深度、射流合并高度的定量关系式 .分数维关联维数表明大型双射流流化床是一个确定性混沌系统 ,考查了管间距、静床高度对关联维数的影响

HYDRODYNAMIC CHARACTERISTICS IN LARGE JETTING FLUIDIZED BED WITH DOUBLE NOZZLES

In a Ф0.5m×8m semicircular jetting fluidized bed with double nozzles using millet as fluidized material, studies of various flow regimes, i.e.,separate jet regime, transition flow regime and jet coalescence regime were carried out.The equations of transition of flow regimes were proposed.Experimental results indicated that penetration depth increased with increasing jet gas velocity,while penetration depth decreased with decreasing nozzle pitch.A relationship of penetration depth and nozzle distance in a large jetting fluidized bed with double nozzles was obtained.With smaller nozzle distance, jet coalescence always occurred and jet coalescence height replaced the penetration depth.Thus,a correlation of jet coalescence height was also presented.Meanwhile, deterministic chaos theory was used to investigate the flow hydrodynamic characteristics in the bed.When p/d 0 is equal to 5.48,the curve of correlation dimension vs .jetting gas velocity showed a maximum increase rate corresponding with complex flow structure.Correlation dimension increased with static bed height.