颗粒脱离壁面时湍流诱导的随机振荡现象研究

Study of Turbulence-Induced Stochastic Oscillatory Phenomena During Particle Detachment From the Wall Surface

颗粒再悬浮是很多自然现象和工业过程中广泛存在的现象。颗粒脱离壁面的过程包含了颗粒-壁面黏附,湍流-颗粒相互作用等物理机制,研究颗粒再悬浮过程对预测颗粒再悬浮率,开发颗粒清除技术有着重要意义,但至今仍然没有一个统一的理论能够描述颗粒脱离壁面准确过程。本文对球形单颗粒再悬浮过程进行了高速显微摄像实验,发现了颗粒脱离壁面时湍流诱导的颗粒随机振荡现象;研究了颗粒振荡频率与颗粒粒径的关系,颗粒粒径越小,振荡频率越大。

Particle resuspension from surfaces is ubiquitous and plays a key role in a number of natural and industrial processes.The process of particle detachment from the wall includes particle-wall adhesion,turbulence-particle interaction and other physical mechanisms,and the study of particle resuspension process is of great significance for predicting the resuspension rate of particles and developing the particle removal technology,but so far there is still no unified theory that describes the exact process of particle detachment from the wall.In this paper,high-speed photography experiments are carried out on the re-suspension process of spherical individual particles,and the phenomenon of turbulence-induced random oscillation of particles when they are detached from the wall is observed;the relationship between the frequency of particles'oscillation and particle size is investigated,and the smaller the size of particles is,the larger the frequency of the oscillation is;the dimensionless number describing the motion of particles.