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Analysis And Design Considerations Of A High-Power Density, Dual Air Gap, Axial-Field, Brushless, Permanent Magnet Motor, Chahee Peter Cho

Doctoral Dissertations

Until recently, brush dc motors have been the dominant drive system because they provide easily controlled motor speed over a wide range, rapid acceleration and deceleration, convenient control of position, and lower product cost. Despite these capabilities, the brush dc motor configuration does not satisfy the design requirements for the U.S. Navy's underwater propulsion applications.

Technical advances in rare-earth permanent magnet materials, in high-power semiconductor transistor technology, and in various rotor position-sensing devices have made using brushless permanent magnet motors a viable alternative. This research investigates brushless permanent magnet motor technology, studying the merits of dual-air gap, axial-field, brushless, permanent …

The Stability Of Flow Over An Elastic Boundary, Paul Joseph Schall

Doctoral Dissertations

Experiments with printing presses show unusual behavior when a fluid flows between rubber and rigid roller. For better understanding of this behavior, three problems which address the stability near fluid interfaces are considered. First, the stability of a viscous flow between a rigid boundary and an elastic layer is studied. Of particular interest are cases with large Froude number modeling rotational effect, and cases with an elastic layer thin as compared to the depth of the fluid. Linear stability is considered using a spectral method. Second, the inviscid flow between a rigid boundary and an elastic layer is studied. Two …

Experiments On Transient Natural Convection In Inclined Enclosures Using Calibrated Multichannel Electronic Interferometry And Digital Particle Image Velocimetry, Timothy David Upton

Doctoral Dissertations

Simultaneous quantitative measurements are made of both the temperature and velocity fields for two-dimensional transient natural convection in an inclined rectangular enclosure. The fluid in the enclosure is initially stationary and isothermal. The transient boundary conditions are initiated by instantaneously heating and cooling two opposing walls. All other walls are insulated and nonconducting. The evolution of the flow to steady state is determined for a Prandtl number of 6.38, a Rayleigh number of 1.5 $\times$ 10$\sp5$, and an aspect ratio of 1.0, at angles of inclination of $\pi$/4, $\pi$/2, and 3$\pi$/4. The temperature is measured using calibrated multichannel electronic interferometry, …