Mechanical Engineering Commons^™

Improvement Of Waterjet And Abrasive Waterjet Nozzle, Zheng Li

Dissertations

This investigation is concerned with the improvement of the nozzle design for water and abrasive water jet machining. The mechanism of formation and characteristics of pure water and abrasive water jets are investigated in order to determine quasi-optimal process conditions.

To improve the pure water jet machining, a pulsed water jet nozzle, which employs the principle of the Helmholtz type resonator, is investigated experimentally and numerically. The experiments show the advantages of this nozzle over the commercial nozzle in cutting and cleaning. A numerical solution of the differential equations of continuity, momentum conservation, turbulent kinetic energy and dissipation for two …

Particle Dynamics Modeling Of Vibrating Granular Beds, Yidan Lan

Dissertations

Particle dynamics modeling is done to study the behavior of granular beds subjected to vibrations imposed by a plane boundary which oscillates sinusoidally about a zero mean speed. Significant differences between the lower and higher shaking acceleration regions are found for the granular temperature and solids fraction depth profiles, which characterize the effectiveness of the boundary in fluidizing the beds. When higher accelerations are applied, the temperature is maximum at the vibrating floor and attenuates through the depth, while the solids fraction profiles exhibit a maximum at some intermediate depth. At lower acceleration values, most of the mass is located …

Deposition Of Particles In A Convergent Channel, Hsi-Chung Chiou

Dissertations

The deposition of suspensions for uniform flow in convergent channels under the combined influences of inertia, viscous, gravity and electrostatic image forces were studied theoretically. A two dimensional, steady, incompressible, laminar flow with uniform velocity profile was assumed.

It was found that when the ratio of charge parameter to gravity parameter, Q/G, is greater than 5, the deposition is dominated by the electrostatic image force alone and that the gravity effect can be neglected. When the ratio of charge parameter to gravity parameter, Q/G, is less than 0.001, the image force can then be neglected. It was also observed that …

Deposition Of Suspensions In Convergent Channels Due To Electrostatic Image Forces, Kwok Wah Hui

Dissertations

The deposition of suspensions for uniform flow in convergent channels under the combined influences of inertia, viscous and electrostatic image forces was studied theorectically. The fluid phase was assumed to be two-dimensional, steady, uniform, incompressible and laminar while the particle phase was assumed to be uniform, steady, dilute and with negligible gravity effects.

Since the image force equations for convergent channels have not been derived, it becomes one of the main purposes of this study to perform the derivation of the image force equations. The lengths of the channels were chosen in a way that the exit area is only …