High-performance ocean energy harvesting turbine design – Detailed flow analysis with blade leaning strategy:
01 May 2019-Vol. 233, Iss: 3, pp 379-396
TL;DR: In this article, an analysis of the internal flow of a bidirectional turbine gives an idea of the turbine's internal flow, which is used in an oscillating water column wave energy converter.
Abstract: Oscillating water column wave energy converter is having low efficiency because of its principal component, a bidirectional turbine. An analysis of the internal flow of the turbine gives an idea of...
TL;DR: In this article, the authors investigated the unsteady behavior of an impulse turbine under various constant-flow conditions, such as the variations in the rotation speed, the pressure drop and the torque output of the turbine starting from rest.
TL;DR: In this article, a novel bistable electromagnetic vibration energy harvester (BEMH) is constructed and optimized based on a nonlinear system consisting mainly of a flexible membrane and a magnetic spring.
Abstract: A novel bistable electromagnetic vibration energy harvester (BEMH) is constructed and optimized in this study, based on a nonlinear system consisting mainly of a flexible membrane and a magnetic spring. A large-amplitude transverse vibration equation of the system is established with the general nonlinear geometry and magnetic force. Firstly, the mathematical model, considering the higher-order nonlinearities given by nonlinear Galerkin method, is applied to a membrane with a co-axial magnet mass and magnetic spring. Secondly, the steady vibration response of the membrane subjected to a harmonic base motion is obtained, and then the output power considering electromagnetic effect is analytically derived. On this basis, a parametric study in a broad frequency domain has been achieved for the BEMH with different radius ratios and membrane thicknesses. It is demonstrated that model predictions are both in close agreement with results from the finite element simulation and experiment data. Finally, the proposed efficient solution method is used to obtain an optimizing strategy for the design of multi-stable energy harvesters with the similar flexible structure.
TL;DR: C coupled CAD-CFD automated optimization of the blade leading and trailing edge ratio was performed to maximize the efficiency of a bidirectional impulse turbine with fixed guide vanes to improve performance.
••01 Jan 2021
TL;DR: The vast amount of energy from the waves could meet an important part of the energy demand for humankind as mentioned in this paper, and wave energy is enormous, reliable, and has higher energy density compared to wind power and solar power, and thus offers a good correlation between resource and demand.
Abstract: Marine energy is a major source of renewable energy and yet remains untapped. As the ocean covers about two-thirds of the Earth’s surface, it contains a large amount of energy. Energy can be extracted from the sea exploiting several phenomena, such as salinity gradient (energy from the difference in the salt concentration between seawater and fresh water), temperature gradient, waves, and ocean currents. Among these, ocean waves have tremendous potential as a source of renewable energy. The vast amount of of energy from the waves could meet an important part of the energy demand for humankind. Wave energy is enormous, reliable, and has higher energy density compared to wind power and solar power, and thus offers a good correlation between resource and demand. Waves also offer multiple locations for energy harvesting from the shoreline to deep water. There has been worldwide interest in harnessing this immense power from the ocean that can play a major part to solve our energy problems.
TL;DR: In this paper, the influence of three rotor blade parameters, including rotor blade thickness, rotor blade rotation angle, and rotor blade incident angle, on the efficiency of the impulse turbine was analyzed.
••01 Dec 2009
TL;DR: In this paper, a review of wave energy converter (WEC) technology is presented, focusing on work being undertaken within the United Kingdom, and some of the control strategies to enhance the efficiency of point absorber-type WECs.
Abstract: Ocean waves are a huge, largely untapped energy resource, and the potential for extracting energy from waves is considerable. Research in this area is driven by the need to meet renewable energy targets, but is relatively immature compared to other renewable energy technologies. This review introduces the general status of wave energy and evaluates the device types that represent current wave energy converter (WEC) technology, particularly focusing on work being undertaken within the United Kingdom. The possible power take-off systems are identified, followed by a consideration of some of the control strategies to enhance the efficiency of point absorber-type WECs. There is a lack of convergence on the best method of extracting energy from the waves and, although previous innovation has generally focused on the concept and design of the primary interface, questions arise concerning how best to optimize the powertrain. This article concludes with some suggestions of future developments.
TL;DR: Renewable energy sources from the ocean may be exploited without harming the marine environment if projects are sited and scaled appropriately and environmental guidelines are followed as discussed by the authors, but the ocean environment should be protected while these technologies are developed.
TL;DR: In this paper, the authors describe tourbillonnaires de l'ecoulement secondaire and leur influence on les caracteristiques de couche limite a la paroi d'extremite, including the origin, croissance, and distribution spatiale des pertes dans des passages d'aubes de turbine.
Abstract: Resume des resultats de recherches experimentales effectuees sur les ecoulements secondaires au cours de la derniere decade, dans le but de donner une image de nos connaissances actuelles sur les aspects fondamentaux des ecoulements secondaires. Description detaillee des structures tourbillonnaires de l'ecoulement secondaire et de leur influence sur les caracteristiques de couche limite a la paroi d'extremite, ainsi que de l'origine, de la croissance, et de la distribution spatiale des pertes dans des passages d'aubes de turbine
TL;DR: Results from implicit LES are presented for a broad range of flows and numerical schemes, ranging from the second-order monotone upstream-centered schemes for conservation laws to very high-order weighted essentially non-oscillatory schemes.
Abstract: Restrictions on computing power make direct numerical simulation too expensive for complex flows; thus, the development of accurate large eddy simulation (LES) methods, which are industrially applicable and efficient, is required. This paper reviews recent findings about the leading order dissipation rate associated with high-resolution methods and improvements to the standard schemes for use in highly turbulent flows. Results from implicit LES are presented for a broad range of flows and numerical schemes, ranging from the second-order monotone upstream-centered schemes for conservation laws to very high-order (up to ninth-order) weighted essentially non-oscillatory schemes.
TL;DR: In this article, the authors investigated the influence of the turbine aerodynamic design on the overall plant performance, as affected by the turbine peak efficiency and the range of flow rates within which the turbine can operate efficiently.