Effects of Tip Clearance Size on Energy Performance and Pressure Fluctuation of a Tidal Propeller Turbine

Bao Ngoc Tran, Haechang Jeong, Jun-Ho Kim, Jin-Soon Park and Changjo Yang
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Bao Ngoc Tran: Division of Marine Engineering, Mokpo National Maritime University, 91 Haeyangdaehak-ro, Mokpo 58628, Korea
Haechang Jeong: Division of Marine Engineering, Mokpo National Maritime University, 91 Haeyangdaehak-ro, Mokpo 58628, Korea
Jun-Ho Kim: Division of Marine Mechatronics, Mokpo National Maritime University, 91 Haeyangdaehak-ro, Mokpo 58628, Korea
Jin-Soon Park: Coastal Development and Ocean Energy Research Center, Korea Institute of Ocean Science and Technology, 385 Haeyang-ro, Busan 49111, Korea
Changjo Yang: Division of Marine Engineering, Mokpo National Maritime University, 91 Haeyangdaehak-ro, Mokpo 58628, Korea

Energies, 2020, vol. 13, issue 16, 1-18

Abstract: Unavoidable tip clearance between blade tip and casing shroud plays an important role in the performance and characteristics of a tidal propeller turbine. In this work, the tip-leakage vortex (TLV) induced in the end-wall region was numerically illustrated by using the shear-stress transport (SST) k–ω turbulence model at various flow conditions and different tip-clearance sizes (TCSs). The swirling strength criterion was employed to visualize the tip-leakage vortex trajectory and investigate vortex evolution according to clearance size change. Although TLV occurs in both design and off-design conditions, vortex intensity develops strongly under excess flow rate with increased tip gap. The extreme influence of TCS on the turbine’s generated power and efficiency was predicted in steady simulations for four TCS cases, namely, δ = 0%, 0.25%, 0.5%, and 0.75%. With the extension of the tip gap, turbine performance was drastically reduced because of vigorous turbulent leakage flow combined with considerable volumetric loss. The effect of TCS on pressure fluctuation intensity were also explored on the basis of the transient simulation statistic. Maximal pressure variation amplitude and dominant frequency were presented in spectrum analysis utilizing fast Fourier transform.

Keywords: computational fluid dynamics (CFD); propeller turbine; tip-clearance size (TCS); tip-leakage vortex (TLV); pressure fluctuation (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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