Tip-Bed Velocity and Scour Depth of Horizontal-Axis Tidal Turbine with Consideration of Tip Clearance

Tianming Zhang, Wei-Haur Lam, Yonggang Cui, Jinxin Jang, Chong Sun, Jianhua Guo, Yanbo Ma, Shuguang Wang, Su Shuing Lam, Gerard Hamill

Research output: Contribution to journalArticle

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Abstract

The scouring by a tidal turbine is investigated by using a joint theoretical and experimental approach in this work. The existence of a turbine obstructs a tidal flow to divert the flow passing through the narrow channel in between the blades and seabed. Flow suppression is the main cause behind inducing tidal turbine scouring, and its accelerated velocity is being termed as tip-bed velocity (Vtb). A theoretical equation is currently proposed to predict the tip-bed velocity based on the axial momentum theory and the conservation of mass. The proposed tip-bed velocity equation is a function of four variables of rotor radius (r), tip-bed clearance (C), efflux velocity (V0) and free flow velocity (V∞), and a constant of mass flow coefficient (Cm) of 0.25. An experimental apparatus was built to conduct the scour experiments. The results provide a better understanding of the scour mechanism of the horizontal axis tidal turbine-induced scour. The experimental results show that the scour depth is inversely proportional to tip-bed clearance. Turbine coefficient (Kt) is proposed based on the relationship between the tip-bed velocity and the experimental tidal turbine scour depth. Inclusion of turbine coefficient (Kt) into the existing pier scour equations can predict the maximum scour depth of a tidal turbine with an error range of 5–24%.
Original languageEnglish
Pages (from-to)1-23
JournalEnergies
Volume12
Issue number2450
DOIs
Publication statusPublished - 25 Jun 2019

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Scour
Turbine
Clearance
Turbines
Horizontal
Coefficient
Predict
Piers
Blade
Flow velocity
Rotor
Conservation
Momentum
Rotors
Inclusion
Directly proportional
Radius
Experimental Results

Keywords

  • marine renewable energy; tidal power; tidal turbine-induced scour; turbine wake

Cite this

Zhang, Tianming ; Lam, Wei-Haur ; Cui, Yonggang ; Jang, Jinxin ; Sun, Chong ; Guo, Jianhua ; Ma, Yanbo ; Wang, Shuguang ; Lam, Su Shuing ; Hamill, Gerard. / Tip-Bed Velocity and Scour Depth of Horizontal-Axis Tidal Turbine with Consideration of Tip Clearance. In: Energies. 2019 ; Vol. 12, No. 2450. pp. 1-23.
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author = "Tianming Zhang and Wei-Haur Lam and Yonggang Cui and Jinxin Jang and Chong Sun and Jianhua Guo and Yanbo Ma and Shuguang Wang and Lam, {Su Shuing} and Gerard Hamill",
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Zhang, T, Lam, W-H, Cui, Y, Jang, J, Sun, C, Guo, J, Ma, Y, Wang, S, Lam, SS & Hamill, G 2019, 'Tip-Bed Velocity and Scour Depth of Horizontal-Axis Tidal Turbine with Consideration of Tip Clearance', Energies, vol. 12, no. 2450, pp. 1-23. https://doi.org/10.3390/en12122450

Tip-Bed Velocity and Scour Depth of Horizontal-Axis Tidal Turbine with Consideration of Tip Clearance. / Zhang, Tianming; Lam, Wei-Haur; Cui, Yonggang; Jang, Jinxin ; Sun, Chong; Guo, Jianhua; Ma, Yanbo; Wang, Shuguang; Lam, Su Shuing; Hamill, Gerard.

In: Energies, Vol. 12, No. 2450, 25.06.2019, p. 1-23.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Tip-Bed Velocity and Scour Depth of Horizontal-Axis Tidal Turbine with Consideration of Tip Clearance

AU - Zhang, Tianming

AU - Lam, Wei-Haur

AU - Cui, Yonggang

AU - Jang, Jinxin

AU - Sun, Chong

AU - Guo, Jianhua

AU - Ma, Yanbo

AU - Wang, Shuguang

AU - Lam, Su Shuing

AU - Hamill, Gerard

PY - 2019/6/25

Y1 - 2019/6/25

N2 - The scouring by a tidal turbine is investigated by using a joint theoretical and experimental approach in this work. The existence of a turbine obstructs a tidal flow to divert the flow passing through the narrow channel in between the blades and seabed. Flow suppression is the main cause behind inducing tidal turbine scouring, and its accelerated velocity is being termed as tip-bed velocity (Vtb). A theoretical equation is currently proposed to predict the tip-bed velocity based on the axial momentum theory and the conservation of mass. The proposed tip-bed velocity equation is a function of four variables of rotor radius (r), tip-bed clearance (C), efflux velocity (V0) and free flow velocity (V∞), and a constant of mass flow coefficient (Cm) of 0.25. An experimental apparatus was built to conduct the scour experiments. The results provide a better understanding of the scour mechanism of the horizontal axis tidal turbine-induced scour. The experimental results show that the scour depth is inversely proportional to tip-bed clearance. Turbine coefficient (Kt) is proposed based on the relationship between the tip-bed velocity and the experimental tidal turbine scour depth. Inclusion of turbine coefficient (Kt) into the existing pier scour equations can predict the maximum scour depth of a tidal turbine with an error range of 5–24%.

AB - The scouring by a tidal turbine is investigated by using a joint theoretical and experimental approach in this work. The existence of a turbine obstructs a tidal flow to divert the flow passing through the narrow channel in between the blades and seabed. Flow suppression is the main cause behind inducing tidal turbine scouring, and its accelerated velocity is being termed as tip-bed velocity (Vtb). A theoretical equation is currently proposed to predict the tip-bed velocity based on the axial momentum theory and the conservation of mass. The proposed tip-bed velocity equation is a function of four variables of rotor radius (r), tip-bed clearance (C), efflux velocity (V0) and free flow velocity (V∞), and a constant of mass flow coefficient (Cm) of 0.25. An experimental apparatus was built to conduct the scour experiments. The results provide a better understanding of the scour mechanism of the horizontal axis tidal turbine-induced scour. The experimental results show that the scour depth is inversely proportional to tip-bed clearance. Turbine coefficient (Kt) is proposed based on the relationship between the tip-bed velocity and the experimental tidal turbine scour depth. Inclusion of turbine coefficient (Kt) into the existing pier scour equations can predict the maximum scour depth of a tidal turbine with an error range of 5–24%.

KW - marine renewable energy; tidal power; tidal turbine-induced scour; turbine wake

U2 - 10.3390/en12122450

DO - 10.3390/en12122450

M3 - Article

VL - 12

SP - 1

EP - 23

JO - Energies

JF - Energies

SN - 1996-1073

IS - 2450

ER -