Conceptual design and numerical simulations of a vertical axis water turbine used for underwater mooring platforms

Tian Wenlong,Song Baowei,Mao Zhaoyong 대한조선학회 2013 International Journal of Naval Architecture and Oc Vol.5 No.4

Energy is a direct restriction to the working life of an underwater mooring platform (UMP). In this paper,a vertical axis water turbine (VAWT) is designed to supply energy for UMPs. The VAWT has several controlled blades,which can be opened or closed by inside plunger pumps. Two-dimensional transient numerical studies are presented to determine the operating performance and power output of the turbine under low ocean current velocity. A standard k-εturbulence model is used to perform the transient simulations. The influence of structural parameters, including foil section profile, foil chord length and rotor diameter, on the turbine performance are investigated over a range of tipspeed-ratios ( TSRs ). It was found that turbine with three unit length NACA0015 foils generated a maximum averaged coefficient of power, 0.1, at TSR = 2.

Conceptual design and numerical simulations of a vertical axis water turbine used for underwater mooring platforms

Wenlong, Tian,Baowei, Song,Zhaoyong, Mao The Society of Naval Architects of Korea 2013 International Journal of Naval Architecture and Oc Vol.5 No.4

Energy is a direct restriction to the working life of an underwater mooring platform (UMP). In this paper, a vertical axis water turbine (VAWT) is designed to supply energy for UMPs. The VAWT has several controlled blades, which can be opened or closed by inside plunger pumps. Two-dimensional transient numerical studies are presented to determine the operating performance and power output of the turbine under low ocean current velocity. A standard k-${\varepsilon}$ turbulence model is used to perform the transient simulations. The influence of structural parameters, including foil section profile, foil chord length and rotor diameter, on the turbine performance are investigated over a range of tip-speed-ratios (TSRs). It was found that turbine with three unit length NACA0015 foils generated a maximum averaged coefficient of power, 0.1, at TSR = 2.

Numerical simulations of a horizontal axis water turbine designed for underwater mooring platforms

Wenlong Tian,Baowei Song,James H. VanZwieten,Parakram Pyakurel,Yanjun Li 대한조선학회 2016 International Journal of Naval Architecture and Oc Vol.8 No.1

In order to extend the operational life of Underwater Moored Platforms (UMPs), a horizontal axis water turbine is designed to supply energy for the UMPs. The turbine, equipped with controllable blades, can be opened to generate power and charge the UMPs in moored state. Threedimensional Computational Fluid Dynamics (CFD) simulations are performed to study the characteristics of power, thrust and the wake of the turbine. Particularly, the effect of the installation position of the turbine is considered. Simulations are based on the Reynolds Averaged Navier- Stokes (RANS) equations and the shear stress transport k-u turbulent model is utilized. The numerical method is validated using existing experimental data. The simulation results show that this turbine has a maximum power coefficient of 0.327 when the turbine is installed near the tail of the UMP. The flow structure near the blade and in the wake are also discussed.

Numerical simulations of a horizontal axis water turbine designed for underwater mooring platforms

Tian, Wenlong,Song, Baowei,VanZwieten, James H.,Pyakurel, Parakram,Li, Yanjun The Society of Naval Architects of Korea 2016 International Journal of Naval Architecture and Oc Vol.8 No.1

In order to extend the operational life of Underwater Moored Platforms (UMPs), a horizontal axis water turbine is designed to supply energy for the UMPs. The turbine, equipped with controllable blades, can be opened to generate power and charge the UMPs in moored state. Three-dimensional Computational Fluid Dynamics (CFD) simulations are performed to study the characteristics of power, thrust and the wake of the turbine. Particularly, the effect of the installation position of the turbine is considered. Simulations are based on the Reynolds Averaged Navier-Stokes (RANS) equations and the shear stress transport ${\kappa}-{\omega}$ turbulent model is utilized. The numerical method is validated using existing experimental data. The simulation results show that this turbine has a maximum power coefficient of 0.327 when the turbine is installed near the tail of the UMP. The flow structure near the blade and in the wake are also discussed.

Design, test and numerical simulation of a low-speed horizontal axis hydrokinetic turbine

Tian, Wenlong,Mao, Zhaoyong,Ding, Hao The Society of Naval Architects of Korea 2018 International Journal of Naval Architecture and Oc Vol.10 No.6

A small-scale horizontal axis hydrokinetic turbine is designed, manufactured and studied both experimentally and numerically in this study. The turbine is expected to work in most of China's sea areas where the ocean current velocity is low and to supply electricity for remote islands. To improve the efficiency of the turbine at low flow velocities, a magnetic coupling is used for the non-contacting transmission of the rotor torque. A prototype is manufactured and tested in a towing tank. The experimental results show that the turbine is characterized by a cut-in velocity of 0.25 m/s and a maximum power coefficient of 0.33, proving the feasibility of using magnetic couplings to reduce the resistive torque in the transmission parts. Three dimensional Computational Fluid Dynamics (CFD) simulations, which are based on the Reynolds Averaged Navier-Stokes (RANS) equations, are then performed to evaluate the performance of the rotor both at transient and steady state.

Design, test and numerical simulation of a low-speed horizontal axis hydrokinetic turbine

Wenlong Tian,Zhaoyong Mao,Hao Ding 대한조선학회 2018 International Journal of Naval Architecture and Oc Vol.10 No.6

A small-scale horizontal axis hydrokinetic turbine is designed, manufactured and studied both experimentally and numerically in this study. The turbine is expected to work in most of China's sea areas where the ocean current velocity is low and to supply electricity for remote islands. To improve the efficiency of the turbine at low flow velocities, a magnetic coupling is used for the non-contacting transmission of the rotor torque. A prototype is manufactured and tested in a towing tank. The experimental results show that the turbine is characterized by a cut-in velocity of 0.25 m/s and a maximum power coefficient of 0.33, proving the feasibility of using magnetic couplings to reduce the resistive torque in the transmission parts. Three dimensional Computational Fluid Dynamics (CFD) simulations, which are based on the Reynolds Averaged NaviereStokes (RANS) equations, are then performed to evaluate the performance of the rotor both at transient and steady state.

Structure, Microstructure, and Piezoelectric Properties of Ytterbium-Doped Potassium Sodium Niobate Lead-Free Ceramics

Huan Li,Wenlong Yang,Zhongxiang Zhou,Hao Tian 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.5

The structure, microstructure, and piezoelectric properties of conventionally sintered Yb-doped K0.5Na0.5NbO3(KNN) lead-free ceramics were investigated. Doping the KNN ceramics with Yb2O3 was effective in inhibiting the grain growth in the KNN ceramics and in densifying the ceramics. The 1.0 wt. % Yb-doped KNN ceramics showed the maximum density, about 96.8% of the theoretical density. X-ray diffraction analysis showed that a small number of Yb3+ ions could be incorporated into the matrix of the ceramicsto occupythe α- or β-sites in the crystal lattice, thereby significantly affecting the piezoelectric properties of the ceramics. Enhanced piezoelectric properties (i.e., d33= 135 pC/N, kp = 34.5%, and Qm = 80.2) were obtained for the 0.50 wt. %Yb-doped KNN ceramics.

Effect of kaolin pretreatment on the structure and properties of metakaolin phosphate-based geopolymers

Xin Yu,Chengxin Ren,Wenlong Xu,Lina Xu,Qingbo Tian 한양대학교 청정에너지연구소 2024 Journal of Ceramic Processing Research Vol.25 No.1

This study focused on the preparation of metakaolin-based phosphate-activated geopolymers (MKPGs) using kaolin pretreatedat 950 °C for varying times as a precursor. It was found that kaolinite quickly transformed into amorphous metakaolin (MK)and then transitioned from a disordered phase to an ordered phase, resulting in precipitation of kyanite and mullite withincreasing calcination time. The formation of the kyanite phase had an adverse effect on geopolymerization, which causeda decrease in the strength of the MKPGs. The precipitation of the mullite phase hindered the geopolymerization reactionbetween phosphoric acid and MK, and the geopolymer failed to solidify. As the calcination time increased from 10 min to 60min, the compressive strength of the geopolymers increased and then decreased. The maximum strength of the geopolymerscreated from MK calcined for 30 min was 132.1 MPa.

Numerical investigation on VIV suppression of marine riser with triangle groove strips attached on its surface

Wang, Wei,Song, Baowei,Mao, Zhaoyong,Tian, Wenlong,Zhang, Tingying The Society of Naval Architects of Korea 2019 International Journal of Naval Architecture and Oc Vol.11 No.2

The effects of Triangle Groove Strips (TGS) on Vortex-induced Vibration (VIV) suppression of marine riser are numerically investigated using Computational Fluid Dynamics (CFD) method. The range of Reynolds number in simulations is 4.0 × 10⁴ < Re < 1.2 × 10⁵. The two-dimensional unsteady Reynolds-Averaged Navier-Stokes (RANS) equations and Shear Stress Transport (SST) k-ω turbulence model are used to calculate the flow around marine riser. The Newmark-β method is employed for evaluating the structure dynamics of marine riser. The effect of the height ratio (ε) of TGS on VIV suppression is evaluated. The amplitude responses, frequency responses, vortex patterns and the flow around the structures are discussed in detail. With the increase of the height ratio of TGS, the suppression effect of TGS on VIV suppression is improved firstly and then weakened. When ε=0.04, the suppression effect of TGS is the best. Compared with the VIV responses of smooth marine riser, the amplitude ratio is reduced by 38.9%, the peak of the lift coefficient is reduced by 69% and the peak of the drag coefficient is reduced by 40% when Re=6.0 × 10⁴. With the increase of Reynolds number, the suppression effect of TGS on VIV suppression is improved firstly and then weakened. When the Reynolds number is 7.0 × 10⁴, the amplitude ratio can be reduced by 40.1%. As to the large-amplitude vibration cases, the TGS show nice suppression effect on VIV.

Numerical investigation on VIV suppression of marine riser with triangle groove strips attached on its surface

Wei Wang,Baowei Song,Zhaoyong Mao,Wenlong Tian,Tingying Zhang 대한조선학회 2019 International Journal of Naval Architecture and Oc Vol.11 No.2

The effects of Triangle Groove Strips (TGS) on Vortex-induced Vibration (VIV) suppression of marine riser are numerically investigated using Computational Fluid Dynamics (CFD) method. The range of Reynolds number in simulations is 4.0 104 < Re < 1.2 105. The two-dimensional unsteady Reynolds-Averaged Navier-Stokes (RANS) equations and Shear Stress Transport (SST) k-u turbulence model are used to calculate the flow around marine riser. The Newmark-b method is employed for evaluating the structure dynamics of marine riser. The effect of the height ratio (ε) of TGS on VIV suppression is evaluated. The amplitude responses, frequency responses, vortex patterns and the flow around the structures are discussed in detail. With the increase of the height ratio of TGS, the suppression effect of TGS on VIV suppression is improved firstly and then weakened. When ε ¼ 0.04, the suppression effect of TGS is the best. Compared with the VIV responses of smooth marine riser, the amplitude ratio is reduced by 38.9%, the peak of the lift coefficient is reduced by 69% and the peak of the drag coefficient is reduced by 40% when Re ¼ 6.0 104. With the increase of Reynolds number, the suppression effect of TGS on VIV suppression is improved firstly and then weakened. When the Reynolds number is 7.0 104, the amplitude ratio can be reduced by 40.1%. As to the large-amplitude vibration cases, the TGS show nice suppression effect on VIV.