Investigation of windage splits in an enclosed test fixture having a high-speed composite rotor in low air pressure environments

Liu, H.-P.; Werst, M.D.; Hahne, J.J.; Bogard, David G.

doi:10.1109/tmag.2004.839295

Cited by 8 publications

(1 citation statement)

References 4 publications

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“…Operation of flywheel systems at atmospheric pressure conditions would lead to high losses in terms of wasted energy and could result in overheating of the flywheel rotor [4]. To control the level of losses, the flywheel is enclosed in containment to create a vacuum environment because the losses reduce with a higher vacuum (i.e., absolute pressure), but not proportionally [5]. The losses can be fully eliminated by increasing the vacuum but its maintenance will be harder due to leaks and outgassing as a result of increased pressure ratio [6].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Standby Losses and Charging Cycles in Flywheel Energy Storage Systems

Amiryar

Pullen

2020

Energies

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Aerodynamic drag and bearing friction are the main sources of standby losses in the flywheel rotor part of a flywheel energy storage system (FESS). Although these losses are typically small in a well-designed system, the energy losses can become significant due to the continuous operation of the flywheel over time. For aerodynamic drag, commonly known as windage, there is scarcity of information available for loss estimation since most of the publications do not cover the partial vacuum conditions as required in the design of low loss energy storage flywheels. These conditions cause the flow regime to fall between continuum and molecular flow. Bearings may be of mechanical or magnetic type and in this paper the former is considered, typically hybridized with a passive magnetic thrust bearing. Mechanical bearing loss calculations have been extensively addressed in the open literature, including technical information from manufacturers but this has not previously been presented clearly and simply with reference to this application. The purpose of this paper is therefore to provide a loss assessment methodology for flywheel windage losses and bearing friction losses using the latest available information. An assessment of windage losses based on various flow regimes is presented with two different methods for calculation of windage losses in FESS under rarefied vacuum conditions discussed and compared. The findings of the research show that both methods closely correlate with each other for vacuum conditions typically required for flywheels. The effect of the air gap between the flywheel rotor and containment is also considered and justified for both calculation methods. Estimation of the bearing losses and considerations for selection of a low maintenance, soft mounted, bearing system is also discussed and analysed for a flywheel of realistic dimensions. The effect of the number of charging cycles on the relative importance of flywheel standby losses has also been investigated and the system total losses and efficiency have been calculated accordingly.

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Section: Introductionmentioning

confidence: 99%

Analysis of Standby Losses and Charging Cycles in Flywheel Energy Storage Systems

Amiryar

Pullen

2020

Energies

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Modeling and experimental validation of flow phenomena for optimum rotor blades of a new type permanent magnet generator

2019

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In this study, flow phenomena through the axial fan and the rotor dynamic performance analysis of a permanent magnet generator with three phases has been explored for a wide velocity range by using an Ansys-Fluent computational fluid dynamics package. In this respect, velocities of dependence angle for a flat blade have been analyzed, numerically. The self-sustained air cooling performance has been optimized in order to provide more efficient machine, namely the number of blades and blade angles have been considered as different input parameters in the simulations. As a result of simulations, the optimum flat angle of the blade is determined after having the highest velocity value from the outlet of the simulation. Besides, the rotor fan power is obtained from the pressure differences between the inlet and outlet. According to the results, the highest velocity has been predicted as 1.86 m/s and power has been calculated as 0.48 W at 65 degrees of blade. In addition, the optimum number of blade has been ascertained as 40 and the velocity for this blade geometry has been found as 1.39 m/s. Consequently, the optimum rotor blade angle and number have been determined as 65 degrees and 40, respectively.

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Fan characteristics of the self-support components of rotor ends and its performance matching

Ding

Liu

Zhang

2017

International Journal of Heat and Mass Transfer

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Investigation of windage splits in an enclosed test fixture having a high-speed composite rotor in low air pressure environments

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

Cited by 8 publications

References 4 publications

Analysis of Standby Losses and Charging Cycles in Flywheel Energy Storage Systems

Analysis of Standby Losses and Charging Cycles in Flywheel Energy Storage Systems

Modeling and experimental validation of flow phenomena for optimum rotor blades of a new type permanent magnet generator

Fan characteristics of the self-support components of rotor ends and its performance matching

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