Abstract-Modern technology combined with the desire to minimize the size and weight of a ship's power system are leading to renewed interest in more electric or all electric ships. An important characteristic of the emerging ship power system is an increasing level of load variability, with some future pulsed loads requiring peak power in excess of the available steadystate power. This inevitably leads to the need for some additional energy storage beyond that inherent in the fuel.With the current and evolving technology, it appears that storage will be in the form of batteries, rotating machines, and capacitors. All of these are in use on ships today and all have enjoyed significant technological improvements over the last decade. Moreover all are expected to be further enhanced by today's materials research. A key benefit of storage is that, when it can be justified for a given load, it can have additional beneficial uses such as ride-through capability to restart a gas turbine if there is an unanticipated power loss; alternatively, storage can be used to stabilize the power grid when switching large loads. Knowing when to stage gas turbine utilization versus energy storage is a key subject in this paper. The clear need for storage has raised the opportunity to design a comprehensive storage system, sometimes called an energy magazine, that can combine intermittent generation as well as any or all of the other storage technologies to provide a smaller, lighter and better performing system than would individual storage solutions for each potential application.

Abstract--Performance testing of the model-scale CPA was recently completed at the University of Texas Center for Electromechanics. A major part of the project was the development of design and simulation codes that would accurately represent the performance of pulsed alternators. This paper discusses the components of the system and its operational sequence. Details of the performance simulation model are presented along with test data. The test result is compared to the predicted data.

The frictional windage losses associated with non-ventilated airflows in the air gaps between the rotor and stator of a high speed rotating machine can greatly influence the rotor outer and stator inner surface temperatures. The characteristics of the radial and axial air-gap flows have been of general interest in many engineering applications. A rotating air gap flow is very complex, and in general, can be categorized as a continuum flow, slip flow, and free molecule flow, depending on the ratio of its mean free path to the air gap dimension. For a continuum flow between concentric rotating cylinders, secondary flow of rows of circumferential Taylor vortices in the air gap due to centrifugal flow instability of a curved flow at relatively high rotating speeds will typically be formed. As the air pressure in the air gap drops significantly, rarefied gas flow, departure from continuum flow, occurs when the mean free path becomes relatively large compared to the air gap dimension. This paper has developed and summarized an analytical approach to predict high speed windage losses (rotor tip velocities up to 900 m/s) at low rotor cavity air pressures (0.1 torr to 10 torr). The predicted transient windage losses at various air pressures and high rotor speeds are compared with measured windage losses generated in continuum and slip flow regimes. The agreements between the predicted and measured windage losses are relatively well.

Abstract-The University of Texas at Austin Center for Electromechanics (UT-CEM

Abstract--The compulsator stator armature winding includes multiple conductor layers. Each conductor layer is made of insulation wraps and transposed aluminum litz wire bundles with epoxy potting compound between the wires and the wire bundles. For a typical pulse-duty application, based on a room-temperature electrical loss calculation, the temperature rise in the aluminum winding is approximately 30°C per shot. Adequate active cooling must be provided such that the stator insulation can survive thermally under a certain pulse repetition rate. The thermal management is quite challenging since the heat loss in the litz wires needs to be conducted through multiple insulations before reaching the coolant passages. As a result of the low equivalent thermal conductivities of the stator winding in the transverse direction, without compromising the overall structural integrity of the winding, the coolant passages have to be allocated as close as possible to the heat sources. For a given electric gun firing mission, four different cooling configurations have been investigated and analyzed by using water ethylene glycol mixture as an active liquid coolant. In this paper, thermal analysis cooling parameters, transient stator winding temperature distributions, hot-spot temperature histories are presented, discussed, and compared.