Monthly Archives: September 2013

Wave electricity production in Italian offshore: A preliminary investigation


Silvia Bozzi, Renata Archetti, and Giuseppe Passonic – Renewable Energy, February 2014

Abstract

In this paper the feasibility of wave energy exploitation off the Italian coasts is investigated. At this aim, the energy production and the performance characteristics of three of the most promising and documented wave energy converters (AquaBuOY, Pelamis and Wave Dragon) are estimated for two of the most energetic Italian locations. The sites are Alghero, on the western coast of Sardinia and Mazara del Vallo, on the Sicily Strait and they have respectively an average annual wave power of 10.3 kW/m and 4 kW/m, and an available annual wave energy of 90 MWh/m and 35 MWh/m. Continue reading

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Filed under Resource Assessment, Resource Characterization

The automation of PDE-constrained optimisation and its applications


Simon Funke, Doctoral Dissertation, Imperial College, UK, 2013

Abstract

This thesis is concerned with the automation of solving optimisation problems constrained by partial differential equations (PDEs). Gradient-based optimisation algorithms are the key to solve optimisation problems of practical interest. The required derivatives can be efficiently computed with the adjoint approach. However, current methods for the development of adjoint models often require a significant amount of effort and expertise, in particular for non-linear time-dependent problems. This work presents a new high-level reinterpretation of algorithmic differentiation to develop adjoint models. This reinterpretation considers the discrete system as a sequence of equation solves. Applying this approach to a general finite-element framework results in an automatic and robust way of deriving and solving adjoint models. Continue reading

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Filed under Modeling

Numerical Analysis of Impulse Turbine for Isolated Pilot OWC System


Zhen Liu, Jiyuan Jin, Ying Cui, and Haiwen Fan – Advances in Mechanical Engineering, August 2013

Abstract

Oscillating water column (OWC) is the most widely used wave energy converting technology in the world. The impulse turbine is recently been employed as the radial turbine in OWC facilities to convert bidirectional mechanical air power into electricity power. 3D numerical model for the impulse turbine is established in this paper to investigate its operating performance of the designed impulse turbine for the pilot OWC system which is under the construction on Jeju Island, Republic of Korea. The proper mesh style, turbulence model, and numerical solutions are employed to study the velocity and air pressure distribution especially around the rotor blade. The operating coefficients obtained fromthe numerical simulation are compared with corresponding experimental data, which demonstrates that the 3D numerical model proposed here can be applied to the research of impulse turbines for OWC system. Effects of tip clearances on flow field distribution characteristics and operating performances are also studied.

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Filed under Component Development, Modeling

Design of high-efficient and universally applicable blades of tidal stream turbine


Baigong Wu, Xueming Zhang, Jianmei Chen, Mingqi Xu, Shuangxin Li, and Guangzhe Li –Energy, August 2013

Abstract

The tidal stream turbine is the major device we use to obtain the kinetic energy of tides. The blades of the rotor are one of the essential parts which can convert tidal current energy into mechanical energy. Now most horizontal-axis turbine blade design theories are mostly based on the BEM (blade element momentum) theory and Glauert theory (e.g., WTperf, GHbladed). This paper comes up with a new method – Schmitz design. This method is easier, but they have the same physical philosophy. Also we change the chord length distribution to adapt the low stream velocity. This new hydrofoil increases the startup torque, improves the total performance of the turbine and decreases the thrust coefficient. At the same time we consider the incipient cavitations, tip loss and airfoil loss. We compare the design results with the experimental data in the literature. This method can satisfy the requirement of the design.

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Filed under Component Development, Experiments, Modeling