Improvement of Torque Performance of a Vertical Axis Type Marine Turbine for a Water Current Generation System

2010 ◽  
Author(s):  
Tomoki Ikoma ◽  
Shintaro Fujio ◽  
Koichi Masuda ◽  
Chang-Kyu Rheem ◽  
Hisaaki Maeda
Keyword(s):  
Turbine Blades ◽  
Angle Of Attack ◽  
Cross Flow ◽  
Vertical Axis ◽  
Hydrodynamic Forces ◽  
Water Current ◽  
Current Channel ◽  
Marine Current ◽  
Water Turbine ◽  
Type Water

This paper describes the possibility of an improvement of torque performance and hydrodynamic forces on a vertical axis type water turbine, used for marine current generating system. The water turbine analyzed here is based on a Darrieus turbine with vertical blades. We considered possibilities of controlling the angle of attack of blades in order to improve the starting performance and to reduce energy loss during the rotation of the turbine. We used blade-element/ momentum theory in order to investigate the variations appearing in torque performance when the angle of attack were controlled. We also proved the validity of our predictions of hydrodynamic forces on the blade and the turbine, made through CFD calculation, by comparing them with the results of corresponding model tests in a current channel. In the corresponding model test we investigated not only the hydrodynamic forces on the turbine with three fixed blades, but also the inline force and the cross-flow force on the rotating turbine with three blades. Regarding the cyclic pitching of turbine blades, results suggest that significant increase in average turbine torque is possible.

Development of a Vertical Axis Type Marine Turbine Model With Variable-Pitch Blades and Its Basic Performance

2011 ◽  
Author(s):  
Tomoki Ikoma ◽  
Koichi Masuda ◽  
Chang-Kyu Rheem ◽  
Yusuke Yoshimura ◽  
Hisaaki Maeda
Keyword(s):  
Model Experiment ◽  
Turbine Blades ◽  
Vertical Axis ◽  
Statistical Investigation ◽  
Velocity Range ◽  
Low Velocity ◽  
Inertia Moment ◽  
Variable Pitch ◽  
Pitch Control ◽  
Marine Current

This paper describes performance of a vertical axis type marine turbine with variable-pitch blades for marine current power utilization. A cyclic mechanism is applied to pitch control of turbine blades. In this paper, the experimental model is developed, which type is variable pitch control one. At the first, conditions of marine currents around Japanese islands is explained, the necessarily of development of marine turbines in low to middle current velocity range is shown. Effectiveness of pitch control of a vertical axis turbine is described from results of CFD calculations. In the calculations, as the basic model, which pitch angles are fixed, that of a past experimental study is applied. From these investigations, the vertical axis type water turbine with variable-pitch blades for model experiment in a channel is developed. Detail of the model developed is introduced. The model experiment is explained. In the experiment, performance of the self-starting and the number of rotations of the turbine is measured. From the results, effectiveness of the pitch control is shown. However, the characteristics are different between past quasi-statistical investigation with the single stream theory and the experimental results. From the experiments, it is confirmed that the turbine of the variable-pitch types can start by itself in very low velocity range in which conventional vertical axis turbines cannot start and also rotate even if the inertia moment is acted.

Study on the Flow Field of an Undershot Cross-Flow Water Turbine

2014 ◽  
Vol 620 ◽  
pp. 285-291 ◽  
Author(s):  
Yan Rong Li ◽  
Yasuyuki Nishi ◽  
Terumi Inagaki ◽  
Kentarou Hatano
Keyword(s):  
Free Surface ◽  
Flow Field ◽  
Water Depth ◽  
Open Channel ◽  
Rotation Speed ◽  
Cross Flow ◽  
Water Turbine ◽  
Low Head ◽  
New Type ◽  
Type Water

The purpose of this investigation is to research and develop a new type water turbine, which is appropriate for low-head open channel, in order to effectively utilize the unexploited hydropower energy of small river or agricultural waterway. The application of placing cross-flow runner into open channel as an undershot water turbine has been under consideration. As a result, a significant simplification was realized by removing the casings. However, flow field in the undershot cross-flow water turbine are complex movements with free surface. This means that the water depth around the runner changes with the variation in the rotation speed, and the flow field itself is complex and changing with time. Thus it is necessary to make clear the flow field around the water turbine with free surface, in order to improve the performance of this type turbine. In this research, the performance of the developed water turbine was determined and the flow field was visualized using particle image velocimetry (PIV) technique. The experimental results show that, the water depth between the outer and inner circumferences of the runner decreases as the rotation speed increases. In addition, the fixed-point velocities with different angles at the inlet and outlet regions of the first and second stages were extracted.

Observation and Discussion of Leading Edge Vortex Shedding From Laboratory-Scaled Cross-Flow Hydrokinetic Turbines in Counter-Rotating Configurations

2021 ◽  
Author(s):  
Minh Doan ◽  
Yuriko Kai ◽  
Takuya Kawata ◽  
Ivan Alayeto ◽  
Shinnosuke Obi
Keyword(s):  
Vortex Shedding ◽  
Power Output ◽  
Turbine Blades ◽  
Cross Flow ◽  
Leading Edge ◽  
Vertical Axis ◽  
Freestream Velocity ◽  
Leading Edge Vortex ◽  
Hydrokinetic Turbines ◽  
Edge Vortex

Abstract In 2011, John Dabiri proposed the use of counter-rotating vertical-axis wind turbines to achieve enhanced power output per unit area of a wind farm. Since then, various studies in the wind energy and marine hydrokinetic (MHK) literature have been dedicated to pairs of vertical axis turbines in both co-rotating and counter-rotating configurations, in terms of their power production, wake characterization, and optimal array design. Previous experimental works suggest an enhancement of up to 27.9% in the system power coefficient of pair configurations compared to a single turbine. Additionally, previous numerical studies have indicated that the increased power output is correlated with higher torque on the turbine blades which correspondingly produces a stronger leading edge vortex. This paper presents an extended investigation into a pair of laboratory scaled cross-flow hydrokinetic turbines in counter-rotating configurations. Experiments were conducted to observe, compare, and discuss the leading edge vortex shedding from the turbine blades during their positive torque phase. The turbines operated in a small water flume at the diameter-based Reynolds number of 22,000 with a 0.316 m/s freestream velocity and 4% turbulent intensity. Using a monoscopic particle image velocimetry setup, multiple realizations of the water flow around each blade at their positive torque phase were recorded and phase-averaged. Results show consistent leading vortex shedding at these turbine angles while a correlation between the turbine power performance and the vortex size and strength was observed.

Tank Model Testing on the Fish Cage Installed in Variable Depths in Current and Waves

2013 ◽  
Author(s):  
Daisuke Kitazawa ◽  
Hiroki Shimizu ◽  
Yoichi Mizukami
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Current Velocity ◽  
Angle Of Attack ◽  
Hydrodynamic Forces ◽  
Water Current ◽  
Mooring System ◽  
Water Tank ◽  
Tank Model ◽  
Water Current Velocity

A fish cage should be submerged to reduce hydrodynamic forces from high waves if the fish cage is installed in an exposed sea area. Usually, the submergible fish cage is suspended from the framework at a fixed depth. The framework is set by floats and anchors at the middle position between water surface and the top surface of the submergible fish cage. The submergible fish cage will be used not only for reduction of hydrodynamic forces but for the other purposes such as choosing the best environment for cultured fishes in the vertical direction, and escaping from the flood with high-level nitrogen or turbidity, harmful algal blooming, and floating ices. In such cases, it is useful for the fish cage to be installed in variable depths. The purpose of the present study is to examine the safety of the fish cage installed in variable depths in current and waves by means of tank model testing. The mooring system consists of a fish cage and four floats. The vertical position of the fish cage is variable by adjusting the buoyancy of these floats. First, the drag of the fish cage was examined by towing test, and the results were compared with the drag estimated by the existing studies. The effects of interaction among twines, the angle of attack, wake, and the top and bottom nets were discussed. Then the fish cage was moored in the water tank, which has the length of 50 m and the width of 10 m. The tank model has a scale of 1/100 of the full-scale model of the fish cage used for tuna farming. The model was made according to Tauti’s similarity law. The water depth was set at 0.68 m by adjusting the position of the variable floor. The motion of the fish cage and four floats, and the tension of the mooring lines between the fish cage, floats, and anchors were measured by the underwater video camera and load cells, respectively. As a result, the drag of the fish cage could be estimated from the experimental results of the drag of a plane net since the results include the effect of interaction among twines. The effects of the angle of attack and the reduction in water current velocity inside the cage were also taken into account. The drag of the fish cage could be estimated well by the above method, while it was underestimated by 10% in comparison with the experimental data. In the water tank testing of the mooring system, the tension of the mooring line increased rapidly with the increase in water current velocity since the drag of the fish cage was proportional to the 1.8th power of water current velocity and increased due to the inclination of the fish cage. The increase in the tension due to wave-induced forces to the fish cage could be negligible when the fish cage was submerged. The safety and the design guideline of the mooring system should be assessed by the simulations using a numerical model, which is being developed by the authors. The experimental data obtained in the present study will be useful for the validation of the numerical model.

Simulation Study for Optimization Design on Vertical Axis Wind Turbine blades

2019 ◽  
Vol 3 (1) ◽  
pp. 136-145
Author(s):  
Arie S. Pangemanan ◽  
Houtman P. Siregar ◽  
Maman Suryaman
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Optimization Design ◽  
Cfd Simulation ◽  
Turbine Blades ◽  
Angle Of Attack ◽  
Vertical Axis ◽  
Evaluation Study ◽  
Vertical Axis Wind Turbine ◽  
Drag Ratio

In this article is conducted research to harness wind energy which is firstly generated by vehicle / truck that is runing on the public road highway. To take advantage of wind energy of the moving truck is designed, otherwise advisor had some ideas during the proposal defense change into fixed vertical axis wind turbine. The purpose of this evaluation study is to get optimization for the design blades of the vertical axis fixed wind turbine and finding the best blades installed and angle of attack will result in highest lift/drag ratio. While other test parameters such as air pressure, wind speed and others are held constant. In this evaluation study the angle of attack are used ranging begin from 45 and until 90 degrees. Evaluation result showed that the best blades install and angle of attack that gives the best lift/drag ratio is 5 blades at AoA ninety degree. Blades diameter of the designed wind turbine are 0.35 m and the number of blades which is the best in analytical of CFD techniques in the designed wind turbine are five pieces. The speed of the wind which is used to test the blades is 8 m/s on turbine rotation 80 rpm. The evaluation study has suceeded to do parametric optimization of the turbine blades. The optimised blades have been ready to re-designed assamble with another componens of the wind turbine to construct the prototype but there some problems / handicaps during the changes the prootype of turbine from movable to fixed wind turbine. The assambled vertical axial wind turbine postponed to further be tested in order to know its performance. CFD simulation has been performed with ten different VAWT designed models. Moving mesh and fluid flow simulation have been developed in CFD software FLUENT. The findings of these numerical simulations provided pressure contour, velocity contour, C D or C L

Experimental and Computational Fluid Dynamic Analysis of Laboratory-Scaled Counter-Rotating Cross-Flow Turbines in Marine Environment

2018 ◽  
Author(s):  
Minh N. Doan ◽  
Ivan H. Alayeto ◽  
Claudio Padricelli ◽  
Shinnosuke Obi ◽  
Yoshitaka Totsuka
Keyword(s):  
Fluid Dynamic ◽  
Magnetic Hysteresis ◽  
Turbine Blades ◽  
Water Channel ◽  
Cross Flow ◽  
Vertical Axis ◽  
Computational Domain ◽  
Computational Fluid Dynamic Analysis ◽  
Angular Velocities ◽  
Marine Hydrokinetic

Power generation of laboratory-scaled marine hydrokinetic (MHK) cross-flow (vertical axis) turbines in counter-rotating configurations was scrutinized both experimentally and numerically. A tabletop experiment, designed around a magnetic hysteresis brake as the speed controller and a Hall-effect sensor as the speed transducer was built to measure the rotor rotational speed and the hydrodynamic torque generated by the turbine blades. A couple of counter-rotating straight-three-bladed vertical-axis turbines were linked through a transmission of spur gears and timing pulleys/belt and coupled to the electronic instrumentation via flexible shaft couplers. A total of 6 experiments in 3 configurations, with various relative distances and phase angles, were conducted in the water channel facility (3.5 m long, 0.30 m wide, and 0.15 m deep) at rotor diameter base Reynolds number of 20,000. The power curve of the counter-rotating turbines (0.068-m rotor diameter) was measured and compared with that of a single turbine of the same size. Experimental results show the tendency of power production enhancement of different counter-rotating configurations. Additionally, the two-dimensional (2D) turbine wakes and blade hydrodynamic interactions were simulated by the shear stress transport k-omega (SST k-omega) model using OpenFOAM. The computational domain included a stationary region and two rotating regions (for the case of counter-rotating turbines) set at constant angular velocities. The interface between the rotating and stationary region was modeled as separated surface boundaries sliding on each other. Velocity, pressure, turbulent kinetic energy, eddy viscosity, and specific dissipation rate field were interpolated between these boundaries.

scholarly journals Blade Polymeric Material Study of a Cross-Flow Water Turbine Runner

2019 ◽  
Vol 56 (2) ◽  
pp. 366-369
Author(s):  
Daniel Catalin Stroita ◽  
Adriana Sida Manea ◽  
Anghel Cernescu
Keyword(s):  
Polymeric Material ◽  
High Power ◽  
Turbine Blades ◽  
Cross Flow ◽  
Water Jet ◽  
Pressurized Water ◽  
Hydraulic Machines ◽  
Turbine Runner ◽  
Water Turbine ◽  
The Cross

Although Romania has a consistent hydro energetic potential, till now is valuated just approximate 30 percent of it. On the big rivers there are already installed high power hydro plants, but a lot of small and medium rivers are not valuated energetically. Installing a new high power hydro plant tends to affect the zone, being necessary a lot of changes in the environment. The Cross-Flow hydraulic turbines don�t need very complex hydro settlements, being very suitable for small and medium power hydro plants. Also a quite big potential in the use this type of hydraulic machines is the energy recovery in the water treatment and sewage plants. The turbine�s blades surfaces enters in contact with the pressurized water jet. The water jet creates a hydrodynamic force that tends to stress the blade. Mainly the Cross-flow turbine blades are made from steel. This article presents the hydrodynamic design and the possibility of using new polymeric material Delrin �AF for the Cross-Flow turbine runner blades, together with the stress analysis.

scholarly journals Perancangan Pembangkit Listrik Pikohydro Dengan Tipe Turbin Screw

2021 ◽  
Vol 14 (2) ◽  
pp. 99-105
Author(s):  
Ma'mun Abdul Karim ◽  
Jojo Sumarjo ◽  
Najmudin Fauji
Keyword(s):  
Output Power ◽  
Turbine Blades ◽  
Electrical Energy ◽  
Small Scale ◽  
Irrigation Flow ◽  
Water Turbine ◽  
Local Residents ◽  
Turbine Shaft ◽  
Type Water ◽  
Head Height

The screw type water turbine is one type of water turbine that has the potential to generate electricity on a small scale that is environmentally friendly, where this screw type water turbine is very suitable for rivers and irrigation flows in the territory of Indonesia because the use or operation of this turbine only requires low turbine head, looking at the potential for irrigation river water flow with a discharge range of 0.01-0.1 m3/s located in the lowlands in a Karawang district, it is possible to install or apply this screw type water turbine. In this study aims to be able to utilize the source of irrigation flow so that it can be converted into a source of electrical energy that can be utilized by local residents and for lighting on roads that are still poorly lit. In the process of designing a screw type water turbine, mechanical calculations are carried out to determine thedimensions of the turbine blades, turbine shaft, transmission systems such as pulleys and belts, as well as the power that can be generated by the turbine, with a relative head between 0.5 meters, 0.75 meters, and 0.9 meters and determine the correct components. The results of this calculation are obtained in the form of output power from each different head height for head 0.5, the power obtained is 220.89795 watts, for the 0.75 m head, the power is 394.29519 watts, and for the height 0.9, the output power is 356.13926 watts, the results of the design will then be made and will be realized.

Image Processing Implementation in Measurement of Cross-Flow Water Turbine Geometry

2014 ◽  
Vol 493 ◽  
pp. 570-575
Author(s):  
Arif Wahjudi ◽  
I. Made Londen Batan ◽  
Bagus Mertha Pradnyana ◽  
Windy Rusweki
Keyword(s):  
Image Processing ◽  
Renewable Energy ◽  
Kinetic Energy ◽  
Measurement System ◽  
Complex Geometry ◽  
Renewable Energy Sources ◽  
Cross Flow ◽  
Water Current ◽  
Energy Sources ◽  
Water Turbine

Recently, many studies have been done to look for renewable energy sources such as kinetic energy from marine or fluvial currents. In its utilization, water turbine plays an important role for taking energy from water current. One of the water turbine types is Cross Flow Water Turbine (CFWT). The performance of the CFWT depends on its geometry. Unfortunately, its geometry is very difficult to be measured using conventional measurement because it has complex geometry. Hence, a non-conventional measurement system based on image processing is proposed in this study to deal with the measurement difficulty of the CFWT geometry.

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