0
research-article

Investigations of compressible turbulent flow in a high head Francis turbine

[+] Author and Article Information
Chirag Trivedi

Mem. ASME, Department of Energy and Process Engineering, Waterpower Laboratory, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway
chirag.trivedi@ntnu.no

1Corresponding author.

ASME doi:10.1115/1.4037500 History: Received January 15, 2017; Revised July 18, 2017

Abstract

Dynamic stability of the high head Francis turbines is one of the challenging problems. Unsteady rotor-stator interaction (RSI) develops dynamic stresses and leads to crack in the blades. In a high head turbine, vaneless space is small and the amplitudes of RSI frequencies are very high. Credible estimation of the amplitudes is vital for the runner design. Current study is aimed to investigate the amplitudes of RSI frequencies considering a compressible flow. Hydro acoustic phenomenon is dominating the turbines, and the compressibility effect should be accounted for accurate estimation of the pressure amplitudes. Unsteady pressure measurements were performed in the turbine during the best efficiency point, and part load operations. The pressure data were used to validate the numerical model. The compressible flow simulations showed 0.5-3% improvement in the time-average pressure and the amplitudes over incompressible flow. The maximum numerical errors in the vaneless space and runner were 6% and 10%, respectively. Numerical errors in the instantaneous pressure amplitudes at the vaneless space, runner and draft tube were ±1.6%, ±0.9% and ±1.8%, respectively. In the draft tube, the incompressible flow study showed the pressure amplitudes up to 8 time smaller than those of the compressible. Unexpectedly, strong effect of RSI was seen in the upper and lower labyrinth seals, which was absent for the incompressible flow.

Copyright (c) 2017 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In