旋流快分系统（VQS）环形空间内气相流场的研究

采用激光多普勒测速仪（LDV）对旋流快分系统（VQS）内环形空间的气相流场进行研究。结果表明，VQS系统内环形空间的气相流场具有双涡特性，内外涡的分界点处存在最大的切向速度。由于流体与双侧壁面之间的摩擦造成能量损失和湍流能量耗散，导致最大切向速度不断衰减且位置沿轴向向下逐渐向提升管外壁移动，同时涡量传递造成外部的准自由涡区逐渐增大，内部的准强制涡区逐渐缩小。轴向速度沿径向呈明显的线性分布，下行轴向速度沿提升管外壁向封闭罩内壁的径向方向逐渐增大。轴向速度的径向梯度沿轴向向下逐渐变小，轴向速度分布也逐渐趋于水平直线状。整个环形空间内，切向、轴向相对湍流强度分布稳定，湍流脉动与扩散比较平缓，有利于气流稳定下行，避免纵向环流、涡旋死区的发生。

STUDY ON FLOW FIELD IN THE ANNULAR SPACE OF VORTEX QUICK SEPARATION SYSTEM

The gas flow field in the annular space of vortex quick separation system (VQS) was measured by Laser Doppler Velocimetry (LDV). The mean velocity and the turbulent intensity of the gas flow field were investigated. The results show that the tangential velocity distribution in the annular space shows a typical feature of strongly swirling flows and it consists of quasi-free vortex area and quasi-forced vortex area. The maximum tangential velocity decreases downwardly and shifts gradually towards the center wall along the axial direction, which are mainly caused by the effects of the friction loss along the wall and the turbulent energy dissipation. Consequently, it leads to the increase of quasi-free vortex area zone and the decrease of quasi-forced vortex area zone. Additionally, the axial velocity distribution in annular space shows a linear characteristic and the downward axial velocity increases outwardly along the radial direction. On the contrary, the radial gradient of axial velocity decreases downwardly along the axial direction. Therefore, the axial velocity distribution becomes horizontal gradually. In the annular space, the relative turbulent intensity of tangential velocity and axial velocity are with the same order of magnitude and having little change along the axial and radial direction. Consequently, the turbulent fluctuation and dissipation have no sharp shift, which are helpful to eliminate the occurrence of circumfluence zone in the annular space.