Papers by Keyword: Particle Separation

Abstract: The mixture two-phase turbulence model and theory of particle dynamics is used to simulate the high concentration water-sand two-phase flow in a hydrocyclone. The article mainly analyzes the particle volumetric concentration distribution and separative efficiency of different diameter particles in a hydrocyclone. The simulation result shows that the particle volumetric concentration distribution of different diameter particles is nonuniform in a hydrocyclone. In the annular space, the small diameter particles are affected by the shortcut flow greatly and have high concentration near the wall of the overflow pipe, while the big diameter particles are mainly distributed near the wall in a hydrocyclone. In cylinder space and cone space, different-diameter particles show a similar distribution, the smaller-diameter particles mainly in inner vortex and the larger-diameter particles in outer vortex.

Abstract: The presented work is an investigation of fluid-particle separation phenomena and compression stress resistance performance of magnetorheological (MR) fluids under squeeze mode. The squeeze mode is very significant to MR machining application. Material used in this study was silicone oil based MR fluid with 20% volume fraction of carbonyl iron particle. Compression test was performed by integrating the developed squeeze mode testing rig with a 50 kN Universal Testing Machine (UTM). The tests were conducted at constant speed and current. Each test was conducted at an initial gap of 2 mm and was stopped at a final gap of 0.5 mm. Force-displacement data was recorded and was analysed using TestExpert® II software. Full factorials with 27 experiments were designed using Design Expert 7 software. Three factors investigated in the design of experiments were carrier fluid viscosity, supplied current, and compression speed. Responses measured were strain energy and compression stress at maximum strain. Macro images of the phenomenon were recorded and evaluated qualitatively. From the compression stress-strain results, carrier fluid viscosity was significant to vary the MR fluid properties. The observed phenomenon shows that fluid-particle separation occurred in the low viscosity carrier fluid, low compression speed and high applied current. The parameters effect on strain energy and compression stress suggests that the fluid-particle separation is significant to the squeeze mode MR fluid performance. The relationship between stress resistance performance and fluid-particle separation phenomena were significant in designing innovative MR fluid devices.

Abstract: Micropost arrays serve as a plaform for the next generation of diagnostic devices. These arrays are found in microfluidic devices for peripheral blood-based diagnostics and metastatic cancer management. The function and performance of these devices is determined by the underlying micro-scale fluid mechanics. Typically, these devices operate in the creeping regime (Re << 1) where the viscous forces of the fluids dominate. Recent advances in manufacturing allow for higher Reynolds number flows (Re >> 1) where the inertial forces dominate. In this work, we use computational simulations to show there is a transitional region (1 < Re < 20) in between the laminar and creeping regimes for two different micropost array geometries. Numerical analysis is employed to investigate jet formation both within the array and at the array exit. The peak-to-peak amplitude of the streamwise normalized velocity profile is used to quantify jet formation within the array; the streamwise velocity profile at the end of the array exit is used to determine jet length at the exit of the array. Above the transitional region (Re > 20) significant jets form downstream of the posts, amplitude scales exponentially and jet length scales with Re according to power law.

Abstract: An accurate and automatic weighting method was used to satisfy the command. The system consisted a hopper, a vibration propellant delivering equipment, a particle separation equipment and control system. The main controller and the programmed logic controller were used to control the system to make sure the high precision of particles weighting as host computer and slave computer respectively. The result shows that the method can solve the key technology of the automatic weighting of the small-bore experimental cartridge and offers significance for the automatic weighting of standard particles.

Abstract: In travelling-wave electric fields, particles are propelled along electrode arrays by a propulsion force. The propulsion force depends on an applied frequency, voltage and size of particles. In this paper, we present the separation method of micro particles using the propulsion force and inclined gravity. The suspensions of polystyrene beads were used as the method to demonstrate the general application for the selective retention or transportation of particles. The efficiency of the method depends on the size of particles and mass density of particles. Additionally the method can measure the propulsion force on particles by adjusting the inclined angle.

Abstract: This paper presents the theory, design, and evaluation of a smart device for the enhanced separation of particles mixed in fluid. The smart device takes advantage of the ultrasonic standing wave, which was generated by the operation of a piezoceramic PZT patch installed in the smart device. The details of the device design including the electro-acoustical modelling for separation and PZT transducer are described at first. Based on this design, the separation device was fabricated and evaluated. In the experiments, an optical camera with a zoom lens was used to monitor the position of particles within the separation channel layer in the device. The electric impedance of the PZT patch bonded on the separation device was measured .The device shows a strong levitation and separation force against 50μm diameter particles mixed with water at the separation channel in the device. Experimental results also showed that the device can work at both heavy and light sand particles mixed with water due to the generated standing wave field in the separation channel.