摘要
以修正后适用于低雷诺数下粒子在离心泵叶轮内运动方程为基础,给出离心泵内流场粒子成像测速(Particle imagevelocimetry,PIV)测试中示踪粒子跟随性的数学表述。据此对离心泵内流场中示踪粒子的运动进行数值计算,讨论粒子跟随性对粒子物理特性和离心泵内流场性质的依赖关系。并在现有几种模型基础上对比讨论各项力对粒子跟随性的贡献,指出各模型的优缺点。计算结果表明,密度接近流体的密度的中性悬浮粒子跟随性较好;对于密度较大的粒子只有粒子直径足够小才能跟随到一定范围内湍流角频率的流动;粒子径向跟随性比周向复杂得多;在离心泵叶轮内低速漩涡区粒子跟随性较差,尤其是在径向方向上;离心泵叶轮旋转引起的离心力和科氏力以及流道弯曲产生的离心力对粒子跟随性影响很大。通过了解和掌握这些因素的影响,对于离心泵内流场PIV测试中采用合适的示踪粒子和控制粒子跟随性误差具有重要的理论指导意义。
Based on the correction particle motion equation for low particle Reynolds number in the impeller of centrifugal pump, the following features of tracer particles in response to the flow field of centrifugal pump is described mathematicaUy. The particle motions are investigated numerically, and the two aspects of influencing factors on the relative motion between tracer particles and liquid medium are discussed. Based on several kinds of computation model, the effects of each force on the flow following behaviours are comparatively studied, and then the advantages and disadvantages of each model are pointed out. The results show that the neutral suspended particles with the same density as fluid have good ability to follow the fluid motion. The larger density particles only with smaller diameter can follow a certain frequency range of turbulent flow. The radial following feature is more complex than the circumferential one. The following feature of tracer particles is bad at the area of low-speed vortex, especially in the radial direction. The Coriolis force and the centrifugal force caused by rotating impeller strongly influence the following feature of tracer particles, also including the centrifugal force caused by the impeller curved channel. Through understanding and grasping these influencing factors, it will be helpful to choice tracer particles to increase the accuracy of flow measurements by particle image velocimetry in the centrifugal pump.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2012年第20期174-181,共8页
Journal of Mechanical Engineering
基金
国家杰出青年科学基金(50825902)
江苏省自然基金攀登(BK2009006)
江苏省研究生创新计划(CXLX12_0641)资助项目
关键词
离心泵
影响因素
示踪粒子
跟随性
Centrifugal pump Influential factors Tracer particles Following behaviors
