Vertical-axis Current Turbine Research Articles

Low Speed Vertical Axis Current Turbine (LS-VACT): Experimental Results

Depleting of fossil fuels and climate change problem as well as the pollutions arise make the renewable energy one of the best options for long-term usage. In hydropower energy extraction, vertical axis marine current turbine applications; Savonius turbine, which has the ability to operate in low speed current is suitable with the Malaysia’s sea conditions. However, due to the drawbacks which are low efficiency and low tip speed ratio, modifications need to be done to harness more power. Low Speed Vertical Axis Current Turbine is appeared to extract energy based on the Savonius rotor. In conjunction to this matter, laboratory work has been done in a way to study the relationship between Power Coefficient (Cp) and Tip Speed Ratio (λ), and also the relationship between Torque Coefficient (Ct) and Tip Speed Ratio (λ) at different current speed which are 0.32 m/s and 0.64 m/s.

Fish Farm Electrification Utilising a Hybrid Device of Low-Speed Vertical Axis Turbine and Solar Panels

The demand for seafood is continually increasing. The best way to meet that is through the aquaculture. In Malaysia, the important alternative source of fish supply is the fish-farms. Nowadays, fish-farms use unclean and expensive energy, which cannot meet the environmental and climate goals. This paper presents a hybrid device consisting of two Low-Speed Vertical Axis Current Turbines (LS-VACTs), generators, batteries, controller and solar-panels. This device is used as a hybrid solution because of the lake of electricity, low water/marine current speed surrounding the fish-farms and variable nature of both resources solar and marine-currents. This device has lower cabling and infrastructure requirements and reduced capital costs. This paper investigates the performance of the hybrid system and predicting power take-off and the number of solar panels required to provide sufficient energy for fish-farm using MATLAB-Simulink environment. The experimental results of LS-VACT show that the turbine has a power coefficient (CP) = 19.4% and high torque coefficient of 0.76 at a speed of 1 m/s. The simulation results indicate that the power output of the system can provide 20 kWh/day with water/marine current speed higher than 1 m/s. This combination of both resources can sustain and produce enough power for electrification of fish-farm.

Performance investigation of self-adjusting blades turbine through experimental study

In the quest for renewable energy sources and sustainable development, hydrokinetic energy available in marine currents, river currents, water flows and man-made canals should be harnessed. This is particularly true for rural and remote areas, which have access to water but often have poor electricity. The vertical axis current turbine, which is a key hydrokinetic technology, has been greatly improved over the last few years. It has numerous advantages, including independency of flow direction, design simplicity, quiet operation, no required yaw mechanism and low cost. The Savonius hydrokinetic turbine is one of the most important drag-type configurations of a vertical axis current turbine. However, it suffers from negative torque, negative drag force on the returning blades, low efficiency and difficulty interfacing with a generator. This paper proposes a novel drag-based vertical axis current turbine using arms and self-adjusting blades. This novel design was developed based on the framework of a Savonius hydrokinetic turbine. In an effort to decrease the hydrodynamic resistance of the returning blades and increase the total output torque of the turbine, this study aims to investigate the performance characteristics of a novel vertical axis current turbine (hereinafter referred to as “self-adjusting blade turbine”). Experimental tests were conducted in the Universiti Teknologi Malaysia (UTM) at low speed currents to assess the performance characteristics of three configurations of a fixed blade turbine and a self-adjusting blade turbine. The force acting on one blade of the self-adjusting turbine was analysed in detail. The results showed that the arm length and blade angle affected the performance of turbine, and that there was 30.7% increase in performance for the self-adjusting blade turbine compared to the fixed blade turbine.

Research on the Hydrodynamic Performance of a Vertical Axis Current Turbine with Forced Oscillation

For a current turbine fixed on a floating platform, the wave-induced motion responses of the platform change the hydrodynamic performance of the current turbine. In this paper, a numerical simulation method based on commercial computational fluid dynamics software-CFX is established to systematically analyze the turbine loads condition and power output efficiency of the turbine subject to the wave-induced motion. This method works well in terms of 2D hydrodynamic performance analysis and is verified by an experiment. In addition, the method is applied to investigate the hydrodynamic performance of a vertical axis current turbine under forced oscillation by a combining sliding mesh with moving mesh technique. This research mainly focusses on the effects of oscillation frequency and oscillation amplitude on the hydrodynamic performance and the flow field. It is found that a wake flow similar to the Von Karman Vortex Street appears under sway oscillation. Spacing between vortex in the wake flow changes under surge oscillation. The fluctuations of the blade load coefficients can be decomposed into a low frequency part and a high frequency part. The low frequency part is related to the frequency of the forced oscillation, while the high frequency part is a consequence of the rotational frequency of the turbine. The oscillation amplitudes of the turbine load coefficients increase linearly with the growth of oscillation frequency and oscillation amplitude. This paper can provide a useful reference for similar research on the turbine loads condition and power out efficiency of the turbine subject to wave-induced motion. This paper can also provide a reference on the structural design or electronic control of vertical axis current turbines.

Validation of a Coupled Electrical and Hydrodynamic Simulation Model for a Vertical Axis Marine Current Energy Converter

This paper validates a simulation model that couples an electrical model in Simulink with a hydrodynamic vortex-model by comparing with experimental data. The simulated system is a vertical axis current turbine connected to a permanent magnet synchronous generator in a direct drive configuration. Experiments of load and no load operation were conducted to calibrate the losses of the turbine, generator and electrical system. The power capture curve of the turbine has been simulated as well as the behaviour of a step response for a change in tip speed ratio. The simulated results agree well with experimental data except at low rotational speed where the accuracy of the calibration of the drag losses is reduced.

Novel Design of Vertical Axis Current Turbine for Low Current Speed via Finite Volume Method

Now a day, increasing energy demand and environmental effect of fossil fuel cause to replacing fossil fuel with renewable energy. This paper presented novel design of turbine to generate more torque to capture more energy of water and hence cause to high output power. In this work Computational Fluid Dynamics (CFD) using realize k-e turbulence model, have been used to analyses the effect of arm on the static torque and the contours of pressure in different angle of direction for vertical vane turbine. Investigation of arm effect on static torque of vertical vane turbine and comparison between turbine with arm and without arm showed the average torque in vertical vane turbine is higher than without arm. The model settings of validation study was accomplished by comparing simulation of performance of turbine Cp and Cm with the experimental data taken from Hayashi and Hara (2005),that showed realize k-e has good agreement with experimental data.

Experimental Results of a DC Bus Voltage Level Control for a Load-Controlled Marine Current Energy Converter

This paper investigates three load control methods for a marine current energy converter using a vertical axis current turbine (VACT) mounted on a permanent magnet synchronous generator (PMSG). The three cases are; a fixed AC load, a fixed pulse width modulated (PWM) DC load and DC bus voltage control of a DC load. Experimental results show that the DC bus voltage control reduces the variations of rotational speed by a factor of 3.5 at the cost of slightly increased losses in the generator and transmission lines. For all three cases, the tip speed ratio \(\lambda\) can be kept close to the expected \(\lambda_{opt}\). The power coefficient is estimated to be 0.36 at \(\lambda_{opt}\); however, for all three cases, the average extracted power was about \(\sim 19\)\%. A maximum power point tracking (MPPT) system, with or without water velocity measurement, could increase the average extracted power.

Hydrokinetic energy harvesting by an innovative vertical axis current turbine

This study proposes an innovative turbine that consists of a vertical flat plate, which is allowed to rotate freely about a vertical axis of symmetry and exploits the autorotation phenomenon to harvest the energy from the current. This system is called here Vertical Axis Autorotation Current Turbine (VAACT). The VAACT utilizes the extra mass moment of inertia to improve the rotational quality which is state of the art in this turbine. This paper covers the principle behind the VAACT and outlines procedures and results for experiments proving the basic feasibility. Also, the operation of the turbine will be discussed by experimental results of the torque coefficient, performance and kinematic parameters. Tests were conducted in LOC (Laboratory of Wave and Current) at COPPE/Federal University of Rio de Janeiro (COPPE/UFRJ).Utilizing the extra mass moment of inertia on the VAACT causes to extract the energy as an efficient turbine in very low head current. The maximum VAACT efficiency has been obtained experimentally in optimum non-dimensional moment of inertia in range of 0.5 and 0.6.

Arm Effect on Performance of Vertical Axis Current Turbine Using RANS Simulation

Climate changing, electrical demands, rising diesel fuel prices, as well as fossil fuel-based energy is limited and in fact is depleting ,are subjects to use of renewable technologies. Among the different renewable energy technologies, hydro power generation (large and small scale) is the prime choice in terms of contribution to the world's electricity generation by using water current turbines.CFD simulation using two equations turbulence model was carried out to compare performance of conventional savonius turnine and new consept of vertical axis turbine. This study was coducted to reach suitable desigh of vertical axis turbines for capturing more kineticenergy of current via of others esspecially,low current speed.

An Innovative Vertical Axis Current Turbine Design for Low Current Speed

This article presents the new innovative concept for optimal design of Vertical Axis Current Turbines (VACT) applicable in low current speed which is being increasingly used to harness kinetic energy of water and convert it into other useful forms of energy as a clean and renewable energy. Widespread commercial acceptability of these turbo machines depends upon their efficiency. This largely depends upon the geometric features of the hydro turbines such as operation of designed system, joints, number and shape of blades and etc. The concept of VACT was proposed to provide a solution for the case of low current force inflow to vertical axis turbines. VACT has four suitable blades with flexible hinge joint to guide the water in come to reduce the drag force, light shaft and arms with stiff metal to make rigid and strong structure. The current study discusses the components of VAC turbine, rigidity of structure, performance, executive concept, efficiency, material, gearbox, environmental impacts and prevention of water corrosion. The new proposed innovative concept of VACT has flexible hinge connection for changing the blades directions automatically to reduce hydrodynamic drag and increase the hydrodynamic pressure to rotate the main shaft and enhance the efficiency as well. Main shaft connected to epicyclical gearbox to provide the higher torque for maximum electric power generation.