流场转速对旋流分离性能影响研究

Experimental Study of Influence of Flow-field Rotating Speed on Hydrocyclone Separation Performance

应用欧拉-拉格朗日方法,对双锥型液-液分离旋流器内不同入口速度条件下的分离性能进行数值模拟及试验,得出随着旋流场转速的逐渐增大,旋流分离效率逐渐升高。为研究旋流分离过程中不同流场转速对分离性能的影响因素,采用粒子成像测速技术(PIV)对旋流样机内部速度场进行测量试验,并采用高速摄像技术记录了变转速旋流场内离散相分离过程。结果表明:流场转速对旋流分离性能的影响除离心力外,还受到轴向截面上二次衍生涡流数量及分离过程中油核摆动幅度的影响;本文研究的旋流结构内随着流场雷诺数的增加,轴向截面上二次衍生涡流数量逐渐减少。当雷诺数Re≥2.51×10~5时,可以忽略轴向截面上二次衍生涡流对分离性能产生的不利影响;旋流分离过程中流场低转速旋转时油核摆动幅度较大,使离散相分离轨迹发生偏移,使旋流分离性能降低。测量范围内油核摆动最大幅值像素坐标差为100,在t=5.2 s后油核摆动幅值为0,此时可以忽略油核摆动对旋流分离性能的不利影响。

Eulerian-Lagarange method was used to simulate and test hydrocyclone separation performance under different inlet flow velocity conditions,and it was concluded that as the rotating speed of the swirling-flow field increased gradually,the separation efficiency of the hydrocyclone increased gradually.In order to explore influence factors on separation performance under different flow-field rotating velocity conditions,an organic glass hydrocyclone was designed and made to measure the different rotating speeds in the spiral flow field by Particle Image Velocimetry(PIV)technique.The separation process of the discrete phase in the spiral flow field of variable rotating speed was recorded using a high-speed camera.The PIV results show that besides the separation performance of spiral flow in hydro-cyclone is affected by the rotating speed through the centrifugal force,it is also affected by the number of secondary derived vortex flows on the axial section and the oscillation amplitude of oil nucleus in the centrifugation process.The number of secondary derived vortex flows on the axial section decreased gradually as the Reynolds number increased in the prototype hydro-cyclone flow field.When Re≥2.51×105,the adverse effect of secondary derived vortex on the axial section on separation performance can be neglected.When the flow field rotates at low speed in the spiral flow separation process,the oscillation amplitude of oil nucleus is relatively big,making the separation trajectory of discrete phase oil droplets offset,causing decreased separation performance of the hydro-cyclone.The maximum displacement from axis of vortex field was 100-pixel distance.After t=5.2s,the oscillation amplitude of oil nucleus was 0,at this moment the adverse effect of oil nucleus oscillation on separation performance was negligible.