粉体力学教学课件：6 动力学 2

1、粉体力学126 动力学KINEMATICS6.1 Introduction6.2 Energy Dissipation Postulate6.3 Mass Flow Rates6.4 Blocked and Obstructed Apertures6.5 Discussion36 动力学6.3 Mass flow rates6.3.1 Some general observations6.3.2 Experimental method6.3.3 Analysis of data6.3.4 Effect of width of vessel6.3.5 Flow through circular

2、apertures from wide vessels6.3.6 Flow through jet6.3.7 The effect of restricting air entry6.3.8 Flow from flat-bottomed vessels through central slots6.3.9 Two regimes of flow troughs through slots46 动力学6.3 Mass flow rates6.3.5 Flow through circular apertures from wide vessels每一点都是由约14个测量值得出高速流动对孔板厚度

3、0-0.5cm的变化非常敏感。 56 动力学6.3 Mass flow rates6.3.5 Flow through circular apertures from wide vessels假设Rm=R0假设rb=const66 动力学6.3 Mass flow rates6.3.5 Flow through circular apertures from wide vessels61cm26Q2/5=26Q=262.5 g/s = =12.4 ton/h 344.69/10002 ton 1/3600 h 344.7g/s 12.4t/h55g/s 0.2t/h76 动力学6.3 Mass

4、 flow rates6.3.5 Flow through circular apertures from wide vesselsb3=0.91 b变化不大当颗粒之间存在内聚力，甚至是轻微的内聚力，要求料仓宽度比自由流动的料仓宽。D/T=4.8/15.2=0.3D/T=1.8/30.5=0.06D/T=0.5/7.6=0.06686 动力学6.3 Mass flow rates6.3.6 Flow through jetBinham $ Wikoff，length=0.2-20cm，f 0.15-0.36cm。Length1cm时可以发现流动速度随着长度的增加呈线性增加，也可根据管径的增加推

5、测出来。 Y3 0.02cmY2 0.037cmY1 0.053cm96 动力学6.3 Mass flow rates7.6cm0.635cm 6.3.7 The effect of restricting air entryRichard实验结果表明速度约为6 cm/s的低速空气使粉体流速减半，8 cm/s的空气，可以有效地阻止粉体流动 。106 动力学6.3 Mass flow rates6.3.8 Flow from flat-bottomed vessels through central slots116 动力学6.3 Mass flow rates6.3.8 Flow from f

6、lat-bottomed vessels through central slots假设Rm=R0假设rb=const该理论适用于2D和3D126 动力学6.3 Mass flow rates6.3.9 Two regimes of flow troughs through slots黄铜30.510.2 cm 砂纸改变粗糙度2 90Reservoir with slot outlet测量时流量保证数据为整个流动中间的五分之三，时间在20100秒(不少于12秒)。加料量：满料、3/4和1/2时，实验观察流率都没有变化。136 动力学6.3 Mass flow rates6.3.9 Two regimes of flow troughs through sl