Open center tidal turbine: How a new mooring system concept affects the performances

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cfd investigation of the open center on the performance of a tidal current turbine

In the present paper, a revision of the layout of an innovative open center self-balancing tidal turbine is presented. Initially, the design was characterized by a central deflector, responsible fo ..

Design and Numerical Analysis of a Double Rotor Turbine Prototype Operating in Tidal Currents

Abstract This work shows the results of a study carried out for several years by the Department of Mechanical, Energy and Management Engineering (DIMEG), in collaboration with SintEnergy Srl. The aim was to develop an innovative marine turbine, taking advantagesfrom the tidal currents. The turbine, which is made-up of two concentric contra-rotating rotors, has been designed to operate anchored to the coast without any supporting structures on the seabed. An iterative procedure, based on a zero-dimensional approach, was developed for the estimation of blades dimensions as well as the rotors performances in terms of lift, drag, power coefficient and efficiency. In order to validate the results of the design procedure, numerical simulations based on three-dimensional analysis were also carried out. The three dimensional study was carried out using the commercial code FLUENT, which follows the Reynolds Averaged Navier-Stokes (RANS) approach, in conjunction with the two-equation Realizable k- ɛ turbulence model

Transients Analysis of a Tidal Currents Self-balancing Kinetic Turbine with on Shore Basement

Abstract The aim of increasing the share of renewable energy sources to the total energy production has brought a significant increase of the interest in marine energies over the last years. Within them, tidal currents resources have been gaining ground for their advantages in terms of predictability, nonexistence of extreme flows, high load factor, minimal land occupation and visual impact. The authors, working in this field since many years, have been designing a new turbine able to work in the water like a kite, with no support structures, but easily connected to the coast by a rope. The constructive easiness, together with lower installation costs, are the main machine characteristics. Moreover it is able to overturn itself when the tidal current changes direction. The turbine equilibrium and mainly the transients related to the sink and surface phases, machine overturning, represent a critical aspect of the design. In the present work, starting from a phenomenological analysis, a simulation of the transients has been carried out in Simulink ® environment. The study, related to the center of gravity, has pointed out the importance of the correct floating stabilizer design which helps the turbine to reach the equilibrium conditions even in case of flow instability

Levelized Cost of Energy: A First Evaluation for a Self Balancing Kinetic Turbine

Abstract Since 2009, the team DIMEG Unical and SintEnergy srl have been developing an innovative kinetic turbine able to produce energy form tidal currents. The machine is able to maintain the frontal position to the flow only thanks to its geometry and technical solutions. This turbine doesn't need any concrete structure, nor pylons or floating devices; in terms of energy conversion, it doesn't use any nacelle, gearbox, external generator, but only a little stabilizer, a permanent magnetic generator and a coast anchoring system able to retain the machine during the working operations. A first cost evaluation has been performed in this work, together with an approximate LCOE calculation, in order to compare this device to the other ones in the pre commercialization phase. The project is in an early stage of the development, but quite ready for a prototype realization

Computational Fluid Dynamic Analysis of the External Rotor Supporting the Design of a Tidal Kinetic Turbine Prototype

The purpose of this paper is to ascertain the reliability of a zero-dimensional approach, aimed to design a double rotor kinetic turbine prototype, by means of computational fluid dynamic analysis. The interaction between the flow and the blade of the turbine prototype external rotor is evaluated. The calculation is carried out by a three-dimensional analysis using the commercial code FLUENT 15.0. In the present work, the Reynolds Averaged Navier-Stokes approach is used, with the two-equation Realizable k-epsilon turbulence model. The blades profile is a NACA 4412 interacting with flow at an attack angle of 4°, which is kept constant along the blade height. The estimation of the forces acting on the blades allows a more accurate evaluation of the blade lift coefficient, which is useful to design the blades geometry and to compute the power coefficient, previously estimated by the traditional mono-dimensional approach

Analysing stress field conditions of the Colima Volcanic Complex (Mexico) by integrating finite-element modelling (FEM) simulations and geological data

In recent decades, finite-element modelling (FEM) has become a very popular tool in volcanological studies and has even been used to describe complex system geometries by accounting for multiple reservoirs, topography, and het- erogeneous distribution of host rock mechanical properties. In spite of this, the influence of geological information on numerical simulations is still poorly considered. In this work, 2D FEM of the Colima Volcanic Complex (Mexico) is pro- vided by using the Linear Static Analysis (LISA) software in order to investigate the stress field conditions with increas- ingly detailed geological data. By integrating the published geophysical, volcanological, and petrological data, we mod- elled the stress field considering either one or two magma chambers connected to the surface via dykes or isolated (not connected) in the elastic host rocks (considered homoge- neous and non-homogeneous). We also introduced tectonic disturbance, considering the effects of direct faults bordering the Colima Rift and imposing an extensional far-field stress of 5 MPa. We ran the model using the gravity in calculations. Our results suggest that an appropriate set of geological data is of pivotal importance for obtaining reliable numerical out- puts, which can be considered a proxy for natural systems. Beside and beyond the importance of geological data in FEM simulations, the model runs using the complex feeding system geometry and tectonics show how the present-day Col- ima volcanic system can be considered in equilibrium from a stress state point of view, in agreement with the long-lasting open conduit dynamics that have lasted since 1913

Design and Numerical Analysis of a Double Rotor Turbine Prototype Operating in Tidal Currents

Abstract This work shows the results of a study carried out for several years by the Department of Mechanical, Energy and Management Engineering (DIMEG), in collaboration with SintEnergy Srl. The aim was to develop an innovative marine turbine, taking advantagesfrom the tidal currents. The turbine, which is made-up of two concentric contra-rotating rotors, has been designed to operate anchored to the coast without any supporting structures on the seabed. An iterative procedure, based on a zero-dimensional approach, was developed for the estimation of blades dimensions as well as the rotors performances in terms of lift, drag, power coefficient and efficiency. In order to validate the results of the design procedure, numerical simulations based on three-dimensional analysis were also carried out. The three dimensional study was carried out using the commercial code FLUENT, which follows the Reynolds Averaged Navier-Stokes (RANS) approach, in conjunction with the two-equation Realizable k- ɛ turbulence model

Modelling stress field conditions of the Colima Volcanic Complex (Mexico) integrating {FEM} simulations and geological data

In recent decades, finite-element modelling (FEM) has become a very popular tool in volcanological studies and has even been used to describe complex system geometries by accounting for multiple reservoirs, topography, and heterogeneous distribution of host rock mechanical properties. In spite of this, the influence of geological information on numerical simulations is still poorly considered. In this work, 2D FEM of the Colima Volcanic Complex (Mexico) is provided by using the Linear Static Analysis (LISA) software in order to investigate the stress field conditions with increasingly detailed geological data. By integrating the published geophysical, volcanological, and petrological data, we modelled the stress field considering either one or two magma chambers connected to the surface via dykes or isolated (not connected) in the elastic host rocks (considered homogeneous and non-homogeneous). We also introduced tectonic disturbance, considering the effects of direct faults bordering the Colima Rift and imposing an extensional far-field stress of 5MPa.We ran the model using the gravity in calculations. Our results suggest that an appropriate set of geological data is of pivotal importance for obtaining reliable numerical outputs, which can be considered a proxy for natural systems. Beside and beyond the importance of geological data in FEM simulations, the model runs using the complex feeding system geometry and tectonics show how the present-day Colima volcanic system can be considered in equilibrium from a stress state point of view, in agreement with the long-lasting open conduit dynamics that have lasted since 1913