Effect of Fins on the Internal Flow Characteristics in the Draft Tube of a Francis Turbine Model

Seung-Jun Kim, Young-Seok Choi, Yong Cho, Jong-Woong Choi, Jung-Jae Hyun, Won-Gu Joo and Jin-Hyuk Kim
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Seung-Jun Kim: Industrial Technology (Green Process and Energy System Engineering), Korea University of Science and Technology, Daejeon 34113, Korea
Young-Seok Choi: Industrial Technology (Green Process and Energy System Engineering), Korea University of Science and Technology, Daejeon 34113, Korea
Yong Cho: K-water Convergence Institute, Korea Water Resources Corporation, Daejeon 34045, Korea
Jong-Woong Choi: K-water Convergence Institute, Korea Water Resources Corporation, Daejeon 34045, Korea
Jung-Jae Hyun: K-water Convergence Institute, Korea Water Resources Corporation, Daejeon 34045, Korea
Won-Gu Joo: Department of Mechanical Engineering, Yonsei University, Seoul 03722, Korea
Jin-Hyuk Kim: Industrial Technology (Green Process and Energy System Engineering), Korea University of Science and Technology, Daejeon 34113, Korea

Energies, 2020, vol. 13, issue 11, 1-23

Abstract: Undesirable flow phenomena in Francis turbines are caused by pressure fluctuations induced under conditions of low flow rate; the resulting vortex ropes with precession in the draft tube (DT) can degrade performance and increase the instability of turbine operations. To suppress these DT flow instabilities, flow deflectors, grooves, or other structures are often added to the DT into which air or water is injected. This preliminary study investigates the effects of anti-cavity fins on the suppression of vortex ropes in DTs without air injection. Unsteady-state Reynolds-averaged Navier–Stokes analyses were conducted using a scale-adaptive simulation shear stress transport turbulence model to observe the unsteady internal flow and pressure characteristics by applying anti-cavity fins in the DT of a Francis turbine model. A vortex rope with precession was observed in the DT under conditions of low flow rate, and the anti-cavity fins were confirmed to affect the mitigation of the vortex rope. Moreover, at the low flow rate conditions under which the vortex rope developed, the application of anti-cavity fins was confirmed to reduce the maximum unsteady pressure.

Keywords: Francis turbine; anti-cavity fins; draft tube; vortex rope; low flow rates; internal flow characteristics; unsteady pressure (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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