Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Pressure Pulsation Characteristics of Tidal Turbine Using Bidirectional Fluid-Solid Coupling
Mengshang Zhao1, Nina Wang2, Decheng Wan3*
1

School of Ocean Engineering and Technology, Sun Yat-Sen University, Zhuhai, Guangdong, China
2
Key Laboratory of Far-shore Wind Power Technology of Zhejiang Province,
Power China Huadong Engineering Corporation Limited, Hangzhou, China3Computational Marine Hydrodynamic Lab (CMHL), School of Naval Architecture, Ocean and Civil Engineering,
Shanghai Jiao Tong University, Shanghai, China*Corresponding author
demonstrated the average torque increased as the growth the wave high,Zang, Zheng, Zhang, Zhang and Fernandez-Rodriguez(2019), Zhang,Zang, Zheng, Cappietti, Zhang, Zheng and Fernandez-Rodriguez (2021)
carried out model experiments to compare the different anisotropy andeddy current number at the different wave parameters, the results foundwave affected the anisotropy by strengthening wake’s turbulence
intensity, while wave only significantly affected the eddy current number
at the near wake and had little effect on it at far wake, many scholars also
have done a lot of researches on the erosion of turbine with single pile atthe different wave parameters. Besides, wake characteristics at different
cases included the wall roughness, turbulence intensity, blocking ratio,array layout of the multi-unit array, and so on have also been discussed
through model experiments and numerical simulations.

ABSTRACTThe purpose of this research is to study the pressure pulsation andstructural characteristics of the tidal turbine based on bidirectional fluidsolid coupling at three different rotational speeds. The results indicatethat the pressure pulsation increases as the increase of rotational speeds,
the main frequency of pressure pulsation coefficient is blade frequency,
the pressure pulsation at the downstream blade is much stronger. Bladetip develops a maximum deformation and maximum equivalent stress islocated near the blade root. Prestress has little influence on the modal
orders of tidal turbines. The turbine’s modal deformation, from first tothird is dominated by a single blade’s flapping motion, from fifth to sixth
is a couple of flapping and sway.

Due to the influence of waves, the floating tidal turbine may generate
forced motion at different degrees of freedom, many recent studies havefocused on the effect of different freedoms on the tidal turbine.
Hydrodynamic characteristics of the turbine with surging and yawing
coupled motions, surge motions were simulated adopted dynamic meshtechnique using CFX and the formula of hydrodynamic load coefficient
was obtained based on the least square method under different freedomsby (Wang, Xu, Zhu and Wang, 2014, Wang, Cui, Ye, Chen and Zhang ,2019). It was found the hydrodynamic load coefficient at coupled motion
was mainly affected by the surge, the frequency of surge performed amuch stronger effect on the turbine. Although both wind turbines andtidal turbines work at two different fluids (air and water), they follow theBetz' Law, so research methods on tidal turbines can often refer to thewind turbine’s(Huang, Wan and Hu, 2021).

KEY WORDS: tidal turbine; pressure pulsation; bidirectional fluidsolid coupling; blade deformation; modal analysis.

INTRODUCTION
The problems of environmental pollution and the demand for energy
attract people’s attention dramatically as the social development for all
countries in the world (Wang, Sun, Xu, Liu and Bai, 2017). It provides
a new way to reduce environmental pollution for us to use clean
renewable energy as energy supply under the background of massive
energy consumption. In recent years, with the rapid development ofrenewable energy such as solar energy, wind energy, marine energy andso on, marine energy has attracted worldwide attention because of its richreserves and much lower level of development. Tidal current energy, asa kind of marine energy, has attracted many scholars’ attention for its
unique advantages such as high energy density, accurate predictability
and no unrestricted by seasons. Horizontal axis or vertical axis tidal
current turbines are two different tidal turbines that are most widely usedin the development of tidal current energy. Furthermore, horizontal axis
tidal current energy is much more popular and have been adopted among
most of the existing commercial tidal current power stations because of
its high efficiency and stability of the torque.

The fluid-structure coupling characteristics of tidal turbines were alsostudied by many researchers. Experiments and numerical simulations
were also contributed to research blade deformation at yawed inflow
conditions (Park, Park, and Rhee, 2016), the results demonstrated that amuch larger deformation was caused near the blade tip, but the vorticity
near the blade tip decreased distinctly, Ullah, Hussain, Abbas, Ahmad,
Amer and Noman (2019) studied the structural characteristics for a threeblade tidal turbine based on fluid-structure coupling technology using
CFX, the results indicated that the natural frequency of the turbine was
far greater than external frequency under normal load, so resonancewould not occur, fatigue analysis indicated that the turbine can maintainendurance under a higher load than the normal operating load, so it is

The hydrodynamic characteristics are primarily concerned for the tidal
turbine as the main hydraulic machinery. Tian, Ni and Zhang (2020)studied the surface wave effect on the tidal turbine through the threedimensional transient computational fluid dynamics, the results

2712