scholarly journals Forced Motion CFD Simulation and Load Refinement Evaluation of Floating Vertical-Axis Tidal Current Turbines

2020 ◽  
Vol 27 (3) ◽  
pp. 40-49
Author(s):  
Wanchao Zhang ◽  
Yujie Zhou ◽  
Kai Wang ◽  
Xiaoguo Zhou
Keyword(s):  
Least Squares Method ◽  
Vertical Axis ◽  
Lateral Force ◽  
Hydrodynamic Performance ◽  
Speed Ratio ◽  
Time Varying ◽  
Pitching Motion ◽  
Tip Speed Ratio ◽  
Damping Coefficients ◽  
Current Turbine

AbstractSimulation of the hydrodynamic performance of a floating current turbine in a combined wave and flow environment is important. In this paper, ANSYS-CFX software is used to analyse the hydrodynamic performance of a vertical-axis turbine with various influence factors such as tip speed ratio, pitching frequency and amplitude. Time-varying curves for thrust and lateral forces are fitted with the least squares method; the added mass and damping coefficients are refined to analyse the influence of the former factors. The simulation results demonstrate that, compared with non-pitching and rotating turbines under constant inflow, the time-varying load of rotating turbines with pitching exhibits an additional fluctuation. The pitching motion of the turbine has a positive effect on the power output. The fluctuation amplitudes of thrust and lateral force envelope curves have a positive correlation with the frequency and amplitude of the pitching motion and tip speed ratio, which is harmful to the turbine’s structural strength. The mean values of the forces are slightly affected by pitching frequencies and amplitudes, but positively proportional to the tip speed ratio of the turbine. Based upon the least squares method, the thrust and lateral force coefficients can be divided into three components, uniform load coefficient, added mass and damping coefficients, the middle one being significantly smaller than the other two. Damping force plays a more important role in the fluctuation of loads induced by pitching motion. These results can facilitate study of the motion response of floating vertical-axis tidal current turbine systems in waves.

Plate Shape Effect on the Performance of the Vertical Axis Auto Rotation Current Turbine (VAACT)

2014 ◽  
Author(s):  
Ali Bakhshandeh Rostami ◽  
Antonio Carlos Fernandes
Keyword(s):  
Flat Plate ◽  
High Efficiency ◽  
Vertical Axis ◽  
Speed Ratio ◽  
Shape Effect ◽  
Tip Speed Ratio ◽  
Upper Limit ◽  
Plate Shape ◽  
Uniform Current ◽  
Current Turbine

The present paper explores experimentally the performance of two types of hinged plates which rotate about vertical axis when submitted to uniform current. A flat plate configuration and also a flapped plate (say, S shape) configuration have been investigated. The Vertical axis Auto rotation Current Turbine (VAACT) is one degree of freedom system (free to rotate in yaw direction). It is shown that a high efficiency for S shape type can be obtained of the order of 30 percent while flat blade type reaches approximately to 7 percent. Upper limit of tip speed ratio for flat blade type has been expanded approximately 0.9 whereas S shape approaches 1.3.

6-DOF Numerical Simulation of the Vertical-Axis Water Turbine

2011 ◽  
Author(s):  
Xin Wang ◽  
Xianwu Luo ◽  
Baotang Zhuang ◽  
Weiping Yu ◽  
Hongyuan Xu
Keyword(s):  
Vertical Axis ◽  
Hydrodynamic Performance ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Test Model ◽  
Tip Speed Ratio ◽  
Water Turbine ◽  
Tidal Stream ◽  
Static Head ◽  
Tidal Stream Turbine

Recent years, the vertical-axis water turbine (VAWT) is widely used for converting the kinetic energy of the moving water in open flow and with low static head like river and tidal sites. Conventional numerical methods such as disk-stream tube method and vortex panel method have some drawbacks to predict the behaviors and characteristics of the vertical-axis tidal stream turbine. This paper had treated the hydrodynamic performance of a VAWT model experimentally and numerically. Based on the present research, a 6-DOF method coupled with CFD suitable to simulate the rotor movement and predict the hydraulic performance for a VAWT was proposed. Compared with the experiments, the numerical results for the performance of the VAWT model were reasonable. It is also noted that there is a maximum power coefficient near tip speed ratio of 2.5 for the test model.

Vertical Axis Current Turbine (VACT) and its Efficiency

2013 ◽  
Author(s):  
Antonio Carlos Fernandes ◽  
Ali Bakhshandeh Rostami ◽  
Lucas Gomes Canzian ◽  
Sina Mirzaei Sefat
Keyword(s):  
Angular Velocity ◽  
Flat Plate ◽  
Water Channel ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Tip Speed Ratio ◽  
Circulating Water ◽  
Property Changes ◽  
Current Turbine

This study examines the efficiency of a vertical axis current turbine (VACT) according to various non-dimensional mass moments of inertia. The vertical axis current turbine of drag force type with flat plate-shaped blade is tested. From experiments in a circulating water channel the angular velocity, the power coefficient and tip speed ratio of the vertical axis current turbine are obtained. The property changes for various conditions give the relationships between efficiency-related parameters. The maximum power coefficients of experiments occur at the tip speed ratio of approximately 0.35∼0.40. From the experiments, turbine is found to give a 7% power coefficient which related to I* = 0.52.

scholarly journals Study on Hydrodynamic Configuration Parameters of Vertical-Axis Tidal Turbine

2020 ◽  
Vol 27 (1) ◽  
pp. 116-125
Author(s):  
Li Guangnian ◽  
Qingren Chen ◽  
Yue Liu ◽  
Shanqiang Zhu ◽  
Qun Yu
Keyword(s):  
Vertical Axis ◽  
Hydrodynamic Performance ◽  
Numerical Code ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Variation Principle ◽  
Tip Speed Ratio ◽  
Tidal Turbines ◽  
Tidal Turbine ◽  
Vertical Axis Tidal Turbine

AbstractIn this paper, a numerical code for predicting the hydrodynamic performance of vertical-axis tidal turbine array is developed. The effect of the tip speed ratio, solidity, and preset angle on the hydrodynamic performance are discussed using a series of calculations. The load principle of the rotor and the variation principle of the turbine power coefficient are studied. All these results can be considered as a reference for the design of vertical-axis tidal turbines.

Numerical Research on the Characteristics of Lift-Drag Type Vertical Axis Wind Turbine

2012 ◽  
Vol 189 ◽  
pp. 448-452
Author(s):  
Yan Jun Chen ◽  
Guo Qing Wu ◽  
Yang Cao ◽  
Dian Gui Huang ◽  
Qin Wang ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Chord Length ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Vertical Axis Wind Turbine ◽  
Tip Speed Ratio ◽  
Middle Range ◽  
Parabolic Form ◽  
Cfd Method

Numerical studies are conducted to research the performance of a kind of lift-drag type vertical axis wind turbine (VAWT) affected by solidity with the CFD method. Moving mesh technique is used to construct the model. The Spalart-Allmaras one equation turbulent model and the implicit coupled algorithm based on pressure are selected to solve the transient equations. In this research, how the tip speed ratio and the solidity of blade affect the power coefficient (Cp) of the small H-VAWT is analyzed. The results indicate that Cp curves exhibit approximate parabolic form with its maximum in the middle range of tip speed ratio. The two-blade wind turbine has the lowest Cp while the three-blade one is more powerful and the four-blade one brings the highest power. With the certain number of blades, there is a best chord length, and too long or too short chord length may reduce the Cp.

scholarly journals Implementation of Control System for Hydrokinetic Energy Converter

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Katarina Yuen ◽  
Senad Apelfröjd ◽  
Mats Leijon
Keyword(s):  
Control System ◽  
Laboratory Tests ◽  
Vertical Axis ◽  
Load Control ◽  
Speed Ratio ◽  
Energy Converter ◽  
Hydrokinetic Energy ◽  
Tip Speed Ratio ◽  
The Town ◽  
Design Construction

At Uppsala University, a research group is investigating a system for converting the power in freely flowing water using a vertical-axis turbine directly connected to a permanent magnet generator. An experimental setup comprising a turbine, a generator, and a control system has been constructed and will be deployed in the Dalälven river in the town of Söderfors in Sweden. The design, construction, simulations, and laboratory tests of the control system are presented in this paper. The control system includes a startup sequence for the turbine and load control. These functions have performed satisfactorily in laboratory tests. Simulations of the system show that the power output is not maximized at the same tip-speed ratio as that which maximizes the turbine power capture.

scholarly journals Kontrol Angle of Attack untuk Optimasi Daya padaVertical Axis Wind Turbine Tipe Darrieus

2020 ◽  
Vol 8 (3) ◽  
pp. 492
Author(s):  
WAHYU AULIA NURWICAKSANA ◽  
BUDHY SETIAWAN ◽  
IKA NOER SYAMSIANA ◽  
SEPTYANA RISKITASARI
Keyword(s):  
Wind Turbine ◽  
Angle Of Attack ◽  
Vertical Axis ◽  
Speed Ratio ◽  
Trial And Error ◽  
Proportional Integral Derivative ◽  
Vertical Axis Wind Turbine ◽  
Average Efficiency ◽  
Proportional Integral ◽  
Tip Speed Ratio

ABSTRAKVAWT (Vertical Axis Wind Turbine) tipe Darrieus NACA0015 merupakan salah satu model dari turbin angin yang bekerja dengan menggunakan angin sebagai sumber penggerak. Namun dari hasil pengamatan, kecepatan angin yang ada tidak konstan setiap saat. Sehingga dari permasalahan ini perlu suatu kontrol yaitu dengan mengendalikan sudut kerja blade VAWT yang dikenal dengan kontrol angle of attack (AoA). Prinsip kerja kontrol AoA yaitu sudut blade diatur agar VAWT bekerja secara optimum dan dapat meningkatkan efisiensi. Metode kontrol AoA menggunakan PID (Proportional–Integral–Derivative) dengan memberikan nilai trial and error pada Kp, Ki, Kd. VAWT ini menggunakan konstanta TSR (Tip Speed Ratio) yaitu 4. Hasil dari penelitian ini yaitu daya yang dihasilkan VAWT dengan kontrol AoA mendapatkan rata-rata efisiensi sebesar 5.16%, sedangkan VAWT tanpa kontrol mendapatkan efisiensi sebesar 3.49%. Sehingga dapat disimpulkan bahwa dengan kontrol AoA, rata-rata efisiensi dayanya naik sebesar 1.67% dari yang tanpa kontrol.Kata Kunci: Kontrol Angle of Attack (AoA), VAWT, TSR, Efisiensi ABSTRACTVAWT (Vertical Axis Wind Turbine) type Darrieus NACA0015 is one model of a wind turbine that works by using wind as a source of propulsion. Conditions from observations, wind speeds that are not constant every time. So from this problem needs control VAWT by controlling the working angle of the VAWT blade is the angle of attack control (AoA). The principle AoA control is that the blade angle adjusted so that the VAWT works optimally and can improve the efficiency. AoA control method uses PID (Proportional-Integral-Derivative) by providing trial and error values for Kp, Ki, Kd. VAWT uses TSR (Tip Speed Ratio) constant which is 4. The results of this research, VAWT with AoA control get an average efficiency of 5.16%, while without control gets an average efficiency of 3.49%. So it can be concluded that with AoA control, the average power efficiency increases by 1.67% from those without control.Keywords: Angle of Attack (AoA) Control, VAWT, TSR, Efficiency

Optimization of a Vertical Axis Micro Wind Turbine for Low Tip Speed Ratio Operation

2012 ◽  
Author(s):  
Akshay Pendharkar ◽  
Ryan McGowan ◽  
Kevin Morillas ◽  
Mark Pinder ◽  
Narayanan Komerath
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Speed Ratio ◽  
Tip Speed Ratio
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