A bidirectional (oscillating) air flow is central to energy conversion from wave to wire in an oscillating water column based wave energy plant. Several classes of bidirectional turbines, which operate with such an oscillating flow, have been designed and tested with limited efficiencies. A topology which uses fluidic diodes in conjunction with unidirectional turbines is shown to significantly improve the efficiency. The design and test results from several fluidic diodes for such an application are discussed. It is shown that a combination of a fluidic diode and the unidirectional turbine can achieve a very high impedance to reverse flow while having a high efficiency in the forward direction, over a wide range of flow coefficients. Copyright © 2011 by ASME.

V. Jayashankar

S. Kedarnath

Air flow

DESIGN AND TESTS

Flow coefficients

FLUIDIC COMPONENTS

HIGH IMPEDANCE

OSCILLATING WATER COLUMN

REVERSE FLOW

Wave energy

efficiency

Turbines

WAVE ENERGY CONVERSION

Diodes

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Fluidic Components for Oscillating Water Column Based Wave Energy Plants

ASME-JSME-KSME 2011 Joint Fluids Engineering Conference, AJK 2011

The twin unidirectional turbine topology was recently proposed with the promise of very significant improvements in the energy capture in Oscillating Water Column (OWC) based wave energy plants. Here, we present the initial results of the experimental validation of the twin unidirectional impulse turbine topology. A scale model of the concept was built and tested using simulated bidirectional flow. The model consists of two 165 mm impulse turbines each individually coupled to 375 W grid connected induction machines. An oscillatory flow test rig was used to simulate bidirectional flow to test the model. The results of the experiments validate the concept of the twin turbine configuration. The proposed topology utilizes no moving parts and achieves more than 50% efficiency over a broad range of flow coefficients. A comparison with other competing turbines (viz, a twin Wells' turbine, a linked guide vane impulse turbine and a fixed guide vane impulse turbine) is done, based on actual measurements in the Indian wave energy plant. The results from the experiments are scaled to evaluate the design features of a 50 GWh wave energy plant. © 2010 Elsevier Ltd.

Renewable Energy

A twin unidirectional impulse turbine topology for OWC based wave energy plants - Experimental validation and scaling

Experimental results from near shore bottom standing OWC based wave energy plants in Japan and India have now been available for about a decade. Historically the weakest link in the conversion efficiency of OWC based wave energy plants built so far has been the bidirectional turbine. This is possibly because a single turbine has been required to deliver power when the plant is exposed to random incident wave excitation varying by a factor of 10. A new topology that uses twin unidirectional turbines (which features a high efficiency spanning a broad range) is proposed. Using the Indian Wave Energy plant as a case study, it is shown that the power output from such a module considerably exceeds existing optimal configurations including those based on a fixed guide vane impulse turbine, linked guide vane impulse turbine or a Well's turbine. A wave to wire efficiency of the order of 50% over the incident range is shown to be feasible in a credible manner by showing the output at all stages of the conversion process. A frequency domain technique is used to compute the OWC efficiency and a time domain approach used for the power module with the turbine pressure being the pivotal variable. © 2008 Elsevier Ltd. All rights reserved.

A twin unidirectional impulse turbine topology for OWC based wave energy plants

KnE Engineering

Investigation of Check Valve Aerodynamic Characteristics in Different Operating Modes

The Design of High-Efficiency Turbomachinery and Gas Turbines

Thermodynamics of gas-turbine cycles

Fluidic components for oscillating water column based wave energy plants

Journal	ASME-JSME-KSME 2011 Joint Fluids Engineering Conference, AJK 2011
Open Access	No