【作者】 张吉光；

【导师】 沈恒根；

【作者基本信息】 东华大学 ， 机械设计及理论， 2005， 博士

【摘要】 本文采用五孔探针测试了静电旋风分离器（电晕极安装在排气管附近,不通电）的内部流场,并对静电旋风分离器的阻力和效率进行了实验研究。采用修正的^κ-ε湍流模型,在贴体坐标系下,对静电旋风分离器不同电晕极安装位置的气相流场进行数值计算,所得数值计算结果与实验结果基本吻合。 当电晕极贴近排气管安装时,在电晕极安装位置附近,切向速度被剧烈地干扰,表现为切向速度大幅度降低。在整个空间流域,切向速度平均值下降,内外涡旋交界面直径由常规旋风分离器的0.5d_e外移为1.2d_e（d_e为排气管直径）。静电旋风分离器内下行流区的切向速度有所增大（约增加5～13%左右）,上行流区的切向速度明显减小,降低幅度达到20～45%。静电旋风分离器的下行流区内,轴向速度约降低1～4%。 由于电晕极的影响,使得静电旋风分离器的阻力系数有较大幅度地降低,与不安装电晕极的旋风分离器的阻力系数相比较,阻力系数降低了约30%。这里的阻力降低不同于传统的减阻方法（以分离效率的降低为代价）,在不加电压的条件下,仅仅在排气管附近安装电晕极时,与不安装电晕极相比,旋风分离器的总分离效率约提高2～3%,即在排气管上安装电晕极时有降低阻力提高分离效率的作用。 当电晕极安装在排气管与筒体的中间位置时,与电晕极贴近排气管安装时相比,靠近旋风分离器简体的区域内（外涡区）切向速度明显下降,而在内涡区,切向速度有所增加。靠近旋风分离器筒体的外涡区是静电旋风分离器的有效分离空间,从离心力分离的角度来看,外涡区内切向速度明显下降是不利的。另一方面,当电晕极安装在排气管与筒体的中间位置时,能更大幅度地降低静电旋风分离器的阻力系数,与不更多还原

【Abstract】 The data of the three-dimensional velocity distribution in electrocyclone are tested by using the five-orifice pitot on the basis of arranging corona wires near the vortex finder without additional voltage. Moreover, pressure drop and separation efficiency are tested for electrocyclones under different condition.The modified k — ε model are used to compute the gas turbulent flow in the electrocyclones on the basis of body-fitted coordinate system under the different corona wires’ arranging position. The numerical results are in agreement with the tested data.When the corona wires are arranged close to the vortex finder, the tangential velocity fluctuate largely in the place near to corona wires, namely yielding a large decrease. From the whole measuring space, due to the effect of the corona wire, the average tangential velocity decreases, and the diameter of interface of inner-vortex and outer-vortex is increased from normal cyclone’s 0.5de to electrocyclone’s 1.2de (de is the vortex finder’s diameter).Compared with the normal cyclone, the tangential velocity in the downward flow zone for electrocyclone increases by 5%~13%. The tangential velocity in upward flow zone decrease by 20%~45%. In the whole flow zone inside the electrocyclone, the average tangential velocity decreases obviously.Owing to the effect of corona wires, pressure drop coefficient of the electrocyclone with corona wires arranged close to vortex finder decreases by 30% in comparison with normal cyclone without the corona wires. This is the same as the conclusion derived from flow field analysis. At the same time, total separation efficiency increases by 2~3%, because of corona wires arranged close to vortex finder but no voltage, compared with same cyclone without corona wires, namely, the corona wires have effects of increasingseparation efficiency and decreasing pressure drop.When the corona wires are arranged in the center between vortex finder and cylinder, due to the disturbance from the corona wires, in the outer-vortex zone close to cylinder, the tangential velocity decreases a little, but the tangential velocity increases in inner-vortex zone, compared with electrocyclone arranging corona wires close to vortex finder. The outer-vortex zone is effective separation region, in the aspect of centrifugal force separation, it is favorable for tangential velocity to be bigger, however, oppositely the corona wires slower the tangential velocity in outer-vortex zone and thus leads to the decrease of separation effect by centrifugal force. On the other hand, it has benefit for the reduction of pressure drop to arrange corona wires in the center between vortex finder and cylinder. Pressure drop coefficient of electrocyclone is 3.5, it decreases by 48.5% in comparison with normal cyclone without corona wires..Under the condition of corona wires arranged close to vortex finder, models for tangential velocity are given in the zone between the walls of electrocyclone and the outer side of corona wires’ frame work.According to the distributions of electric field and gas flow field, the migration velocity of particles in effective separation zone is derived for electrocyclone. The calculation results and tested data show that it has respectively shortage and advantage to arrange corona wires close to vortex finder or in the center between the cylinder and vortex finder.更多还原