卡鲁塞尔氧化沟反应器三维流场体视PIV测量

Stereoscopic PIV Measurement of 3-Dimensional Flow Field in Carrousel Oxidation Ditch Reactor Model

采用体视PIV(Stereoscopic PIV)技术对卡鲁塞尔氧化沟模型直道、弯道及曝气叶轮段等处三维全场流速进行测量,克服了传统接触式点测量方法无法获取全场流动同步信息的缺陷,分析了不同位置处的流动结构,并对纵、横、垂三向流速沿程分布特点进行了研究和比较。结果表明,纵、垂两向的流动分布是决定沟内水力特性的主要因素;横、垂两向的流动是决定污泥沉积位置的主要因素;外沟靠近曝气叶轮直道段的流速分布上大下小,使低速区底部易发生污泥沉积;外沟远离曝气叶轮直道段流速分布上小下大,利于防止泥水分离;弯道段受横比降和横向环流的影响使内侧容易形成低速区或停滞区而发生污泥沉积;倒伞型叶轮使其附近流场在垂向呈螺旋形分布,利于气、液、固三相的均匀混合。

The Stereoscopic PIV(Particle Image Velocimetry) was applied to investigate the 3-dimensional whole-flow-field velocity in straight channel, flexual channel and impeller section of Carrousel oxidation ditch reactor. Flow structures in different ditches are analyzed and the distribution characters of longitudinal,lateral,vertical velocity along the course of the reactor are compared and discussed. The result shows that longitudinal and vertical flows are the determinative factors of hydraulic characteristic in the reactor. The position of sludge sedimentation primarily depends on lateral and vertical velocity. In the outside ditch near the impeller, the flow rate at the upper part is greater than that at the lower part,which leads to a sludge sedimentation in low speed section. In the outside ditch far away from the impeller, the flow rate at the upper part is lower than that at the lower part, which gets benefit to prevent the sludge separation from wastewater. Beacause of effects of the lateral slope and its circulation flow in the flexural section, the low speed flow and/or stagnancy tends to occur easily in the inboard section. The cone impeller makes spiraling flow in vertical direction, to facilitate mixing gas, liquid and solid.