<section data-role="paragraph" class="_135editor" style="font-size: medium; max-inline-size: 100%; margin: 0px; padding: 0px; border: 0px none; z-index: 0; overflow-wrap: break-word !important; outline: none 0px !important;"><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; line-height: 1.75em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; font-size: 14px; overflow-wrap: break-word !important; outline: none 0px !important;">　　设管道中纯空气时的气流流速为v,管道中输送纤维时,纤维介质的空隙率为ε,则从纤维介质的空隙中透过的流速为v/ε,当流速v较小时,纤维不动,当v逐渐增加时,整个纤维介质膨胀并使ε增大,纤维开始上升,但由于上部的ε增大,从而使v/ε值降低,故纤维又下降,这种上升又下降的现象称为流化,但纤维仍留在管道中,不能达到输送的目的。当v继续增加并超过纤维介质的终末速度vT 时,上升后即不再降落而继续运动,形成输送过程。</span></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; line-height: 1.75em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; font-size: 14px; overflow-wrap: break-word !important; outline: none 0px !important;">　　设气力输送时,管道中纤维的运动速度为vf ,它一般低于空气流速v,两者的相对速度为v-vf ,在垂直管道正常的稳定输送过程中,v-vf =vT ,即v=vT +vf 。因为vf =v-vT ,当纤维介质在垂直管道中产生悬浮时,vf =0,此时使纤维介质在垂直管道中产生悬浮的气流速度称为悬浮速度。可以看出,悬浮速度在数值上等于沉降速度(终末速度),即气流速度达到自由沉降终末速度(终末速度)时,纤维介质在垂直管道中悬浮,当气流速度大于纤维介质的终末速度vT 时,才能进行垂直管道的正常输送。气流速度一般控制在终末速度的1.5～2.0倍。</span></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; overflow-wrap: break-word !important; outline: none 0px !important;"></p><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; line-height: 1.75em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="max-inline-size: 100%; margin: 0px; padding: 0px; cursor: text; font-size: 14px; overflow-wrap: break-word !important; outline: none 0px !important;">　　在垂直管道中输送纤维介质时,如果降低流速到达一定程度时,就会出现纤维介质在管道中某段多、某段少的情况,在纤维较多的一段中,ε较小,纤维介质空隙中透过的空气流速v/ε较高,出现腾涌现象,导致流动不匀,流速再降低就会出现阻塞。每当直立管道中产生螺旋运动时,由于管壁摩擦增加及螺旋运动的能量消耗,容易产生阻塞现象,要求增加输送速度。</span></p><section class="_135editor" data-role="paragraph" id="autoparagraph" style="max-inline-size: 100%; margin: 0px; padding: 0px; border: 0px none; z-index: 0; overflow-wrap: break-word !important; outline: none 0px !important;"><p style="max-inline-size: 100%; margin-bottom: 0px; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br style="max-inline-size: 100%; margin: 0px; padding: 0px; font-family: 微软雅黑, &quot;Microsoft YaHei&quot;, sans-serif; font-size: 17px; caret-color: rgb(255, 0, 0); overflow-wrap: break-word !important; outline: none 0px !important;"></p></section></section>