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<p>The unsteady flow within turbine cavities critically influences both the reliability and aerodynamic performance of turbines. However, unsteady flow mechanisms within cavities, particularly in centripetal turbines, remain largely unexplored. In this study, we employ a rotating disk cavity test rig and Unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations to investigate the unsteady flow characteristics under centripetal mainstream conditions. Our findings reveal that the cavity flow of centripetal turbine exhibits an unsteady phenomenon that is not aligned with the rotor rotational frequency and exhibits complex behavior influenced by the sealing flow rate. Specifically, the characteristic frequency amplitude of the unsteady flow increases initially and then decreases as the sealing flow rate rises. Moreover, unsteady flow structures, driven by Kelvin-Helmholtz instabilities arising from tangential velocity differences between the mainstream and sealing flow, play a pivotal role in gas ingress. The number of structures is negatively correlated with the rotational speed. This study offers new insights into the unsteady flow phenomena in centripetal turbine cavities, with implications for improving turbine sealing and overall performance.</p>

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Experimental and Numerical Investigation of Unsteady Flow in Centripetal Turbine Cavity

  • 期刊论文

  • 发表日期：

    2026年2月6日

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  • Kun Cheng,
  • Zhao Yin,
  • Hualiang Zhang,
  • Yu Liu,
  • Changchun Liu,
  • Yujie Xu,
  • Haisheng Chen

摘要

The unsteady flow within turbine cavities critically influences both the reliability and aerodynamic performance of turbines. However, unsteady flow mechanisms within cavities, particularly in centripetal turbines, remain largely unexplored. In this study, we employ a rotating disk cavity test rig and Unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations to investigate the unsteady flow characteristics under centripetal mainstream conditions. Our findings reveal that the cavity flow of centripetal turbine exhibits an unsteady phenomenon that is not aligned with the rotor rotational frequency and exhibits complex behavior influenced by the sealing flow rate. Specifically, the characteristic frequency amplitude of the unsteady flow increases initially and then decreases as the sealing flow rate rises. Moreover, unsteady flow structures, driven by Kelvin-Helmholtz instabilities arising from tangential velocity differences between the mainstream and sealing flow, play a pivotal role in gas ingress. The number of structures is negatively correlated with the rotational speed. This study offers new insights into the unsteady flow phenomena in centripetal turbine cavities, with implications for improving turbine sealing and overall performance.