Experimental Study of Vertical and Oblique Particle Clouds in Water

Abstract

Sand jets and particle clouds are common in many engineering areas such as marine bed capping, dredging, and artificial island construction. Because of the wide range of their application, a better understanding of particle cloud’s behavior will lead to increase the efficiency of engineering systems and lead to an improvement in predicting the behavior of solid-liquid flows. There are many parameters that can control the behavior of particle clouds behavior such as nozzle diameter do, particle size D50, released mass m, impact velocity of sand particles (at the surface) ui and initial oblique angle of the particle cloud. Moreover, some characteristics of two-phase flows such as entrainment coefficient and drag coefficient can be very important for controlling the impact of the two-phase flow. In this research, laboratory experiments were conducted to find the impact of controlling parameters on the dynamics of vertical and oblique particle clouds in the water media. For considering the impact velocity of sand particles on the surface, the ui was varied by changing the release height H. Nozzle size and mass of particles were grouped to form a non-dimensional parameter as aspect ratio Lo/do, where Lo is a length of sand particles occupied in a pipe with a nozzle diameter of do. It was found that the modified initial energy and circulation are correlated with Lo/do. A direct correlation between the width and frontal velocity of particle clouds with Lo/do was found. These relationships were formulated power law equations and can be used for prediction of cloud size and its frontal velocity. A wide range of particle sizes (D50=0.1375 mm−0.718 mm) was used to study the effects of particle size on spreading of sand jets and particle clouds. Effects of Lo/do and particle size on the evolution of sand particles in water media was also investigated. It was found that particle clouds with small particle sizes (D50=0.1375 mm) formed a sphere shape whereas particle cloud with a large particle size (D50=0.595 mm) forms an arc shape.