Development of a CFD Model for the Estimation of Windage Losses Inside the Narrow Air Gap of an Enclosed High-Speed Flywheel

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Abstract

Concerns over global warming and the need to reduce carbon emissions have prompted the development of novel energy recovery systems. During urban driving, a significant amount of energy is lost due to continuous braking, which can be recovered and stored. The flywheel energy storage system can efficiently recover and store the vehicle's kinetic energy during deceleration. In this study, a Computational Fluid Dynamics (CFD) model was developed to assess the impact of air gap size, and rotor cavity pressure environment on the aerodynamic performance of an enclosed non-ventilated flywheel energy recovery system. Consequently, the flywheel rotor skin friction coefficients for various air gap sizes have been numerically determined to predict the windage losses over a wide operating range. The presented study aims to identify a correlation that accurately fits the rotor skin friction coefficients for a range of air gap sizes and operating conditions. Model validation was carried out to assess the validity of the CFD results, which showed good agreement between numerical and experimental data. The results demonstrated that the increase in the air gap size can lead to up to a 19% reduction in the windage loss depending on the operating speed of the flywheel, while the windage loss can be reduced by 33% when the operating pressure is reduced to 500 mbar. Windage losses can be reduced by 45% when the airgap size is greatest, and the operating pressure is lowest.
Original languageEnglish
Publication statusPublished - 8 Sep 2022
EventThe 3rd International Conference on Energy and Sustainable Futures (ICESF) - Coventry University Campus, Coventry , United Kingdom
Duration: 7 Sep 20228 Sep 2022
https://www.coventry.ac.uk/research/about-us/research-events/2022/icesf-2022/

Conference

ConferenceThe 3rd International Conference on Energy and Sustainable Futures (ICESF)
Country/TerritoryUnited Kingdom
CityCoventry
Period7/09/228/09/22
Internet address

Keywords

  • Energy recovery
  • Mechanical storage
  • Taylor-Couette flow
  • Skin friction coefficient

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