Design and Optimization of a Horizontal Axis Marine Current Turbine

As fossil fuels near depletion and their detrimental side effects become prominent on ecosystems, the world searches for renewable sources of energy. Marine current energy is an emerging and promising renewable energy resource. At the heart of the horizontal axis marine current turbines (HAMCT) are carefully designed hydrofoil sections and optimized blade twist and chord distribution. While there is growing needs to have hydrofoils that provide good hydrodynamic and structural performance, the hydrofoils also have to avoid cavitation due to high suction pressures. This study focuses on designing efficient hydrofoils - HM05XX series; this series has very good hydrodynamic properties and also these sections are thick enough to provide structural strength to the blades. The HM05XX series hydrofoils were used to design and optimize HAMCT. The designed HAMCT has rated operating speed of 1.5 m/s, cut in speed of 0.5 m/s and cut-off speed of 3 m/s. The turbine was optimized using HARP-Opt (Horizontal axis rotor optimization) code that utilizes a multiple objective genetic algorithm and blade-element momentum (BEM) theory flow model to design horizontal-axis wind and hydrokinetic turbine rotors

Design of a horizontal axis wind turbine for Fiji

The demand and cost of electricity has increased for Pacific Island Countries (PICs). The electricity from main grid does not reach rural areas and outer islands of Fiji. They burn fuel for electricity and daily lighting. Therefore, there is a need to look for alternative energy sources. Wind turbine technology has developed over the past years and is suitable for generating electricity by tapping wind energy. However, turbines designed to operate at higher wind speed do not perform well in Fiji, because Fiji’s average wind velocity is around 5-6 m/s. A 10 m, 3-bladed horizontal axis wind turbine is designed to operate at low wind speed, cut in speed of 3 m/s, cut off speed of 10 m/s and rated wind speed of 6 m/s. The blade sections were designed for different locations along the blade. The airfoil at the tip (AF0914) a has maximum thickness of 14% and maximum camber of 9%; the thickness varies linearly to the root, at the root the airfoil (AF0920) has a maximum thickness of 20% and maximum camber of 9%. The aerodynamic characteristics of airfoil AF0914 were obtained using Xfoil and were validated by experimentation, at turbulence intensities (Tu) of 1% and 3%, and a Reynolds number (Re) of 200,000. The aerodynamic characteristics of other airfoils were also obtained at operating Re at the turbulence intensities of 1% and 3%. These airfoils have good characteristics at low wind speed, and were used to design the 10 m diameter 3-bladed HAWT for Fiji. The turbine has a linear chord distribution for easy manufacturing purpose. Twist distribution was optimized using Blade Element Momentum (BEM) theory, and theoretical power and turbine performance were obtained using BEM theory. At the rated wind speed of 6 m/s and a TSR of 6.5, the theoretical efficiency of the rotor is around 46% and maximum power is 4.4 kW. The turbine has good performance at lower wind speeds and is suitable for Fiji’s conditions

Design of a gorlov turbine for marine current energy extraction

As fossil fuels near depletion and their detrimental side effects become prominent on ecosystems, the world searches renewable sources of energy. Marine current energy is an emerging and promising renewable energy resource. Marine current energy can be alternative energy source for electricity production. Many marine current converters are designed to tap marine current energy; however, Gorlov turbine proves to have minimum manufacturing and maintenance cost, hence giving desired power output. A 0.3m diameter and 0.6m long 3 bladed Gorlov turbine was designed, fabricated and test to analyse its performance. The turbine produces average power 15 W and proves to be quite efficient for marine current energy extraction

Design and Performance Analysis of Micro Wind Turbine for Fiji

Today’s major research area is based on finding alternatives to fossil fuels. Wind energy can contribute significantly towards renewable energy production. A functional wind turbine built locally proposes a huge impact for Fiji and the Pacific Islands renewable energy industry. The design has to take into consideration the wind speed of the pacific which is quite different from other countries. A low Reynolds number airfoil was selected and modified for horizontal axis wind turbine (HAWT) and its aerodynamic characteristic was studied. The analysis were done using XFoil software, the numerical results were validated with experimental results before analysis were done. The Q-blade Software is used to design the blade for the wind turbine. The cut in velocity of wind turbine is 3 ms-1 , which is a big achievement when it comes for the power generation. The rated power is 50 watts at rated velocity of 6.5 ms-1 and the cut of velocity is at 20 ms-1 . The numerical results were validated with experimental results. The peak power after measurement was 23.73 watts at wind speed of 8 ms-1

Design of a ducted cross - flow turbine for marine current energy extraction

Marine current energy is a clean energy source and is a solution to the problems faced by burning fossil fuels such as global warming and climate change. Once tapped, the useful shaft power can be converted into electrical energy. To make this practical, the designed energy converter should be capable of operating at low marine current velocities, it should be suitable for installation at locations that have low water depths and should have lower manufacturing, installation and maintenance costs. A ducted cross-flow turbine has all the above features and it will be suitable for Pacific Island countries (PICs) for extracting marine current energy. The ducted cross-flow turbine was designed, modelled and analyzed in commercial Computational Fluid dynamic (CFD) code ANSYS-CFX. The inlet and outlet duct sizes were optimized for maximum output. Before the analysis of full model, the CFD results were validated with experimental results. Simulations for the 1:10 ducted cross-flow turbine (having a diameter of 150 mm) were performed with 400,000 nodes, as increase in the grid size did not make much difference other than increasing the simulation time significantly. The maximum difference in the power coefficient between CFD and experimental results was 6%. Simulations were then performed for the full-scale prototype, which has a duct (nozzle) inlet of 3.5 m x 3.5 m and a turbine diameter of 1.5 m, at three freestream velocities of 0.65 m/s, 1.95 m/s and 3.25 m/s. Analysis of the prototype performance showed that the ducted cross-flow turbine can reach a maximum efficiency of 56% and can produce 21.5 kW of power at a current speed of 1.95 m/s and 103.6 kW at 3.25 m/s. The designed cut-off speed was 4 m/s

Design of a horizontal axis tidal current turbine

Pacific Island Countries (PICs) have a huge renewable energy potential to meet their energy needs. Limited resources are available on land; however, large amount of ocean energy is available and can be exploited for power generation. PICs have more sea-area than land-area. Tidal current energy is very predictable and large amount of tidal current energy can be extracted using tidal current energy converters. A 10 m diameter, 3-bladed horizontal axis tidal current turbine (HATCT) is designed in this work. Hydrofoils were designed for different blade location; they are named as HF10XX. The hydrodynamic characteristics of the hydrofoils were analyzed. A thick hydrofoil with a maximum thickness of 24% and a maximum camber of 10% was designed for the root region. The maximum thickness of hydrofoils was varied linearly from the root to the tip for easier surface merging. For the tip region, a thinner hydrofoil of maximum thickness 16% and maximum chamber 10% was designed. It was ensured that the designed hydrofoils do not experience cavitation during the expected operating conditions. The characteristics of the HF10XX hydrofoils were compared with other commonly used hydrofoils. The blade chord and twist distributions were optimized using BEM theory. The theoretical power output and the efficiency of the rotor were also obtained. The maximum power at the rated current of 2 m/s is 150 kW and the maximum efficiency is 47.5%. The designed rotor is found to have good efficiency at current speeds of 1–3 m/s. This rotor has better performance than some other rotors designed for HATCT

Marine current energy resource assessment and design of a marine current turbine for Fiji

Pacific Island Countries (PICs) have a huge potential for renewable energy to cater for their energy needs. Marine current energy is a reliable and clean energy source. Many marine current streams are available in Fiji’s waters and large amount of marine current energy can be extracted using turbines. Horizontal axis marine current turbine (HAMCT) can be used to extract marine current energy to electrical energy for commercial use. For designing a HAMCT, marine current resource assessment needs to done. A potential site was identified and resource assessment was done for 3 months. The coordinates for the location are 18�1201.7800S and 177�38058.2100E; this location is called Gun-barrel passage. The average depth is 17.5 m and the width is nearly 20 m e the distance from land to the location is about 500 m. A multi cell aquadopp current profiler (ADCP) was deployed at the site to record marine currents. Strong marine currents are recorded at this location, as a combination of both tidal and rip currents. The maximum current velocity exceeds 2.5 m/s, for days with large waves. The average velocity was 0.85 m/s and power density for the site was 525 W/m2. This site has good potential for marine current and HAMCT can be installed to extract power. A turbine with diameter between 5 and 8 m would be suitable for this site. Therefore, a 5 m HAMCT is designed for this location. The HF10XX hydrofoils were used from blade root (r/R = 0.2) to tip (r/R = 1.0). HF10XX series hydrofoil sections were designed to operate at varying turbine operating conditions; these hydrofoils have good hydrodynamic characteristics at the operating Reynolds number. The turbine is designed to operate at rated marine current speed of 1.5 m/s, cut in speed of 0.5 m/s and cut off speed of 3 m/s at a tip speed ratio (TSR) of 4.2

Design and Optimization of a Ducted Marine Current Savonius Turbine for Gun-barrel Passage, Fiji

Marine current energy is a reliable and clean source of energy. Many marine current turbines have been designed and developed over the years. Placement of an appropriately designed duct or shroud around the turbine significantly improves the turbine performance. In the present work, a Ducted Savonius Turbine (DST) is designed and optimized and its performance analysis carried out. The components of ducted Savonius turbines are simple and easily available and can be manufactured in developing countries like Fiji. A scaled-down model of 1/20 of a DST was fabricated and tested in a water stream at a velocity of 0.6 m/s and the results were used to validate the results from a commercial Computational Fluid Dynamics (CFD) code ANSYS-CFX. Finally, a full-scale DST was modeled to study the flow characteristics in the turbine and the performance characteristics. The maximum efficiency of the turbine is around 50% at the tip speed ratio (TSR) of 3.5 and the maximum shaft power obtained is 10 kW at the rated speed of 1.15 m/s and around 65 kW at a free-stream velocity of 2.15 m/s. The stress distribution on the ducted turbine was also obtained

Design of a ducted cross flow turbine for Fiji

Marine current energy is clean and reliable energy source. It can be alternative energy source to produce electricity if tapped with a suitable marine current energy converter. Pacific Island countries (PIC) like Fiji can reduce the amount of Fossil fuel used. However for most energy converters designed perform well at marine current velocities above 2m/s and it needs to be installed at depths of 20 – 40m also installation and the maintenance cost of such devise will be quite high if it needs to be installed in Fiji. Therefore a ducted cross flow turbine was designed, which can give desired output at minimum installation and maintenance cost. A dusted cross flow turbine has been design taking into account for its operating condition. The turbine was modelled and analyzed in commercial; Computational Fluid dynamic (CFD) code ANSYS-CFX. The code was first validated and with experiment results and finally performance analysis of full scale turbine was carried out. The designed turbine can have maximum efficiency of 56% producing rated power of 21kW; it produces 0.77kW at cut in speed of 0.65m/s