基于PIV的循环式生物絮团系统涡旋分离器内流场研究

Investigation on Flow Field in Hydraulic Vertox Separator of Recirculating Biofloc Technology System Based on PIV

为分析循环式生物絮团系统涡旋分离器的内流场特性,基于非接触式流场测试PIV (Particle image velocimetry)技术对试验规模涡旋分离器内流场进行测量,分析了该涡旋分离器在不同水力停留时间工况下(248、83、49 s)涡旋分离器内部流场的合速度、分速度和涡量等分布情况。结果表明:不同水力停留时间条件下,涡旋分离器内套筒内部区域的左下角和上部区域均表现一定的涡旋,同时随着水力停留时间的加快,中间内套筒内的颗粒速度方向大致相同,仅在筒壁附近产生小的二次流,同时沉积仓内的颗粒速度方向趋于一致;虽然水力停留时间加快,但轴向和径向的合速度变化不大,且不同速度占据的比例基本相同;不同工况下顺时针和逆时针涡量基本相同,且水力停留时间越慢,流场的涡量相对越小,并随着水力停留时间加快涡量分布趋向均匀,即高涡量区域逐渐增加; PIV试验由于激光能量一定,其穿透能力有限,因此,对于复杂结构的PIV试验所获得的结果有待改进。

Aiming to analyze the flow field characteristics of the vortex separator in the circulating biological flocculation system, the test scale vortex separator was taken as the research object. The non-contact flow field test technique, particle image velocimetry (PIV) technology, was used to measure the flow field in the test scale vortex separator and analyze different hydraulic powers of vortex separator. The distribution of velocity, velocity and vorticity in the flow field of cyclone separators (248 s, 83 s and 49 s) under residence time condition was analyzed. The results showed that under different HRT conditions, the lower left corner and upper region of the inner region of the vortex separator showed a certain vortex. At the same time, with the acceleration of the HRT, the velocity direction in the inner sleeve was approximately the same, only a small two flow was produced near the wall of the cylinder, and the velocity direction of the particle in the silo was also tending to be the same. Although HRT was accelerated, the axial and radial velocity was changed little, and the proportion of different size and velocity was basically the same; the clockwise and clockwise vortices were basically the same under different conditions, and the slower the HRT was, the smaller the vorticity of the flow field was, and the higher vorticity distribution tended to be uniform with the fast vorticity distribution of the HRT, that was, the high vorticity. The region was gradually increased; the PIV test limited penetration ability because of the certain laser energy. Therefore, the results of the complex structure to the PIV test still needed to be improved. The research results had important reference value for improving the structure of vortex separator and selecting the best working condition.