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/elt.2004.1398078

Cited by 8 publications

(6 citation statements)

References 4 publications

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“…The existing research in the field is limited to selected aspects of these effects, which are usually considered at the later stages of the design process if found to be significant. The majority of work in the field is devoted to more demanding machine designs with forced airor liquid-cooling of the rotor or rotor/stator assembly and/or high speed applications [6]- [10], [19]- [24], [41], [42]. The importance of understanding the rotor windage/drag and heat transfer mechanisms has been acknowledged and investigated for various machine designs [6]- [10], [19]- [29], [41], [42].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Mechanical Loss Components and Heat Transfer in an Axial-Flux PM Machine

Wróbel

Vainel

Copeland

et al. 2015

IEEE Trans. on Ind. Applicat.

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This paper investigates components of mechanical loss together with heat transfer effects in an axial-flux PM motor. The mechanical loss components generated within electrical machines are well known, however, their prediction or derivation has not been widely reported in the literature. These, together with the electromagnetic loss sources and heat transfer effects are crucial and must be accounted for when considering high-power-density, high-speed and/or compact machine designs. This research is focused on separating the mechanical loss components to gain a more in depth understanding of the effects and their importance. Both experimental and theoretical techniques have been employed in the analysis of a machine demonstrator. In particular, hardware tests with dummy rotors have been performed to measure the bearing and windage/drag loss components. These have been supplemented with CFD analysis to theoretically evaluate the aerodynamic effects occurring within the mechanical air-gap accounting for loss and heat transfer. It has been identified that the analysed hardware demonstrator suffered from bearing loss significantly higher than that suggested by the bearing manufacturer. This has been attributed to design of the mechanical assembly accommodating bearings, which resulted in inappropriate bearing preload. The excessive bearing loss had a significant detrimental effect on the machine thermal behaviour. In contrast, the aerodynamic effects have been found to have less pronounced effects here, due to fully enclosed and naturally cooled machine construction.Index Terms-Axial-flux PM machine, mechanical loss, heat transfer, computational fluid dynamics, thermal equivalent circuit, bearing loss, windage loss.

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Section: Introductionmentioning

confidence: 99%

Investigation of Mechanical Loss Components and Heat Transfer in an Axial-Flux PM Machine

Wróbel

Vainel

Copeland

et al. 2015

IEEE Trans. on Ind. Applicat.

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“…This figure may be alternatively expressed as 0.018% of the total storage capacity of the sized SHyKESS flywheel. It is worth noting here that Liu et al [31] have suggested that low pressure environment windage losses are proportional to the square of angular speed. Magnetic bearing lamination core losses may also be expressed using the same relationship.…”

Section: Comments On Turnaround Efficiency and A Case Study Applicatimentioning

confidence: 90%

A series hybrid “real inertia” energy storage system

Rouse

Garvey

Cárdenas

et al. 2018

Journal of Energy Storage

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The wide scale market penetration of numerous renewable energy technologies is dependent, at least in part, on developing reliable energy storage methods that can alleviate concerns over potentially interrupted and uncertain supplies. Many challenges need to be overcome, not least among them is allowing capacity for the wide range of time scales required to ensure grid stability. In thermal power plant, high frequency/short duration demand fluctuations, acting at the milliseconds to several seconds time scale, are addressed passively by the inertia of the grid. Here, grid inertia can be thought of as the mechanical inertia of spinning steel in steam and gas turbines. This allows time for active control measures to take effect at the tens of second to hours time scale and for the system to recover without a supply frequency deviation that is noticeable to the customer. It is of paramount importance that, as thermal plant is retired, renewable energy generation and storage systems account for the loss of this inertia. In the literature, strategies to address the loss of "real" inertia have often relied on emulation rather than actual replacement. The present work focuses on the preliminary development of a novel energy storage system that makes use of real inertia to address short term supply/demand imbalances while simultaneously allowing for extended depths of discharge. The concept looks to combine flywheel and compressed fluid energy stores in order to power a synchronous generator. By combining these energy storage technologies through a differential drive unit, DDU, it is anticipated that the benefits of high system inertia can be exploited in the short term while allowing energy to be continually extracted from the flywheel in the long term during storage discharge. The use of a DDU makes the present design particularly novel and distinct from other hybrid systems. In essence, this inclusion allows energy to be extracted entirely from the flywheel, inducing "real" inertia, or entirely from the secondary store, inducing "synthetic" inertia, or some combination of the two. Fundamental sizing calculations for a 50MW system with 20MWh of storage capacity are presented and used to design a suitable control system that allows for the operation of both primary flywheel and secondary compressed fluid energy stores. The transient behaviour of the system is simulated for several charge/discharge time profiles to demonstrate response stability for the system. Comments on system turnaround efficiency, which is dependent upon loading history but for the intended applications can be considered to be greater than 90% are also made here, along with a case study application to an isolated Californian solar powered grid.

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“…To manage the heat generation in these machines, care must be taken of heat generated by a variety of sources, including friction windage in the gaps between the rotating and stationary elements. Detailed thermal analyses by Liu et al [11], [12] compare predictions with experiments. In some cases, active cooling may be essential in these high performance alternators.…”

Section: Energy Storage and Power Conditioningmentioning

confidence: 96%

Electromagnetic launch science and technology in the United States enters a new era

Fair

2005

IEEE Trans. Magn.

107

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Electromagnetic launch science and technology in the United States is on the threshold of a major new advance in its development. Significant developments in hypervelocity electromagnetic launch and in hypervelocity high-G guidance and control components have provided the impetus for exploring advanced electromagnetic weapon systems capable of providing revolutionary new capabilities. These systems include the electromagnetic launch of aircraft from Navy aircraft carriers, hypervelocity electromagnetic guns on ships to provide protection and to launch guided projectiles to extraordinary ranges, and lightweight ground combat vehicles propelled by hybrid electric power protected by electromagnetic armor and capable of defeating advanced armor targets with lightweight hypervelocity penetrators from electromagnetic railguns. This presentation will summarize many of the technical advances leading to the decision to implement these new engineering efforts.

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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

Investigation of Mechanical Loss Components and Heat Transfer in an Axial-Flux PM Machine

Investigation of Mechanical Loss Components and Heat Transfer in an Axial-Flux PM Machine

A series hybrid “real inertia” energy storage system

Electromagnetic launch science and technology in the United States enters a new era

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