Effect of blade profile on the performance of the Wells self-rectifying air turbine

Otaola

Mathematical Problems in Engineering

et al. 2015

Oscillating Water Column (OWC)-based power take-off systems are one of the potential solutions to the current energy problems arising from the use of nuclear fission and the consumption of fossil fuels. This kind of energy converter turns wave energy into electric power by means of three different stages: firstly wave energy is transformed into pneumatic energy in the OWC chamber, and then a turbine turns it into mechanical energy and finally the turbogenerator module attached to the turbine creates electric power from the rotational mechanical energy. To date, capture chambers have been the least studied part. In this context, this paper presents an analytical model describing the dynamic behavior of the capture chamber, encompassing the wave motion and its interaction with the OWC structure and turbogenerator module. The model is tested for the case of the Mutriku wave power plant by means of experimental results. For this purpose, representative case studies are selected from wave and pressure drop input-output data. The results show an excellent matching rate between the values predicted by the model and the experimental measured data with a small bounded error in all cases, so that the validity of the proposed model is proven.

Section: Introductionmentioning

confidence: 99%

“…Currently, two different types of turbine are mainly used in power plants around Europe, India, Japan, Korea, and so forth [20]: the Wells turbine [21][22][23][24] and impulse turbine [25].…”

Section: Introductionmentioning

confidence: 99%

Mathematical Modeling of Oscillating Water Columns Wave-Structure Interaction in Ocean Energy Plants

Otaola

Mathematical Problems in Engineering

et al. 2015

MATEC Web of Conferences

“…There were many studies done on the effect of different symmetrical and non-symmetrical airfoil profiles on the performance of Wells turbine. The airfoils with thicker profiles improve starting characteristics and performance of the Wells turbine [2,3]. The stall characteristics of Wells turbine can be improved by optimization of airfoil profile.…”

Section: Introductionmentioning

confidence: 99%

Effect of Blade Profiles on the performance of Bidirectional Wave Energy Turbine

Kumar

Samad

2018

Abstract. To fulfill the ever growing demands of world energy consumption, the wave energy should be extracted economically. The oscillating water column is most commonly used to extract energy from waves. It consists of a chamber in which waves drives the entrapped air column to rotate the Wells turbine. The Wells turbine is a self-rectifying low-pressure axial reaction turbine with 90 ο stagger angle. These turbines consist of symmetrical airfoil profile to achieve unidirectional rotation for the bi-directional airflow. The turbine performance predominantly depends on the aerodynamic characteristics of the airfoil profile used. In this study, the performance of Wells turbine with various symmetrical airfoil profiles was analysed using ANSYS CFX 14.5. The CFD analysis was performed by solving three dimensional steady Reynolds averaged Navier-Stokes equation with k-ω SST turbulence closure model. The reference geometry has NACA0015 as blade profile and the CFD results were compared with the experimental values. The performance characteristics of the new airfoil profiles were compared with the reference case to analyse the suitability of airfoils in wave energy extraction. The NACA0021 airfoil profile showed better performance in the post-stall regime compared to the NACA0015 and the S1046 airfoil profiles.

Proceedings of the Indian National Science Academy

“…There has been a variety of turbines developed with flow rectifying valves and without valves. The turbine types varied from the Wells type (Raghunathan, 1985) to impulse turbines (Setoguchi, 2001, Santha Kumar et al, 1998. Similarly, different types of generators/controls were also developed (Ravindran et al, 1997).…”

Section: Ravindran and V S Rajumentioning

confidence: 99%

Ocean Energy

Ravindran¹

2015

Ocean energy is an important and promising renewable energy for the future. Even though extensive technology development and demonstrations have occurred in the areas of ocean thermal energy, wave energy and tidal energy over the last 40 years, commercial plants based on these technologies are very slow in coming up because of the high capital costs. In recent years, due to increase in the fossil fuel costs, renewable energies such as solar photo voltaic systems and wind energy systems have become cost competitive. Ocean energy systems are likely to become cost competitive in a decade or so, especially for remote islands and coastal areas. This chapter presents the highlights of developments in the areas of ocean thermal energy, wave energy and tidal energy. Keywords Ocean EnergyOcean energy, which is an indirect form of solar energy, is a very large resource. The development and demonstration of ocean energy technology has been suffering all along because of high cost of plant structures and offshore infrastructure. The sharp increase in the oil prices has highlighted, once again, the need to develop large-scale renewable energies including ocean energy.The three forms of ocean energy conversion systems which have reached already a ''technology demonstration'' or ''pre-commercial'' phase are:Ocean thermal energy conversion (OTEC)ii. Wave energy conversion (WEC)iii. Tidal energy conversion (TEC)The highest priority of ocean technologists today is to reassess the techno-economic viability of ocean energy plants vs fossil fuel plants, in the context of high oil price and the available carbon credit.The potential of ocean energy in different regions depends on their geographical location with respect to the equator. Countries closer to the equator having tropical seas around them have good potential for OTEC and countries in northern and southern latitudes have a good potential for wave energy. Tidal energy, caused by gravitational pull of moon and sun on the ocean mass of water, is high only in estuaries and bays where the tidal oscillations are amplified. Ocean Thermal Energy Conversion Regional Availability and Current StatusOTEC utilizes the temperature-difference between warm surface sea water of around 27-29 o C in tropical waters and the cold deep sea water of around 5-7 o C, which is available at a depth of 800 to 1000 m, to run a heat engine under Rankine cycle. This temperature differential worldwide and typical temperature depth profiles are shown in Fig. 1 (Ravindran, 2010).The warm surface water exchanges energy with low temperature boiling fluids such as ammonia and