The Optimization of Blade Pitch Settings of an Air Turbine Using Self-Pitch-Controlled Blades For Wave Power Conversion

2001 ◽  
Vol 123 (4) ◽  
pp. 382-386 ◽  
Author(s):  
T. H. Kim ◽  
T. Setoguchi ◽  
K. Kaneko ◽  
M. Takao
Keyword(s):  
Oscillating Water Column ◽  
Flow Conditions ◽  
Irregular Wave ◽  
Turbine Performance ◽  
Air Chamber ◽  
Air Turbine ◽  
Wave Power Conversion ◽  
Wave Conditions ◽  
Starting Characteristics ◽  
Blade Pitch Angle

This work investigated an air turbine with self-pitch-controlled blades operating in the airflow generated by an oscillating water column (OWC) under irregular wave conditions to determine turbine performance and identify the optimum blade pitch angle setting. Rotor models with fixed blades were tested under steady flow conditions. The running and starting characteristics of the turbine under irregular wave conditions were determined from a computer simulation that modeled both the turbine and the air chamber. The performance of the air turbine was evaluated and the optimum rotor blade limit was found to be about 10°.

A Numerical Study of Wave Energy Converter in the Form of an Oscillating Water Column Based on a Mixed Eulerian-Lagrangian Formulation

2010 ◽  
Author(s):  
Chunrong Liu ◽  
Zhenhua Huang ◽  
Adrian Law Wing Keung ◽  
Nan Geng
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Numerical Study ◽  
Integral Equation Method ◽  
Boundary Integral ◽  
Lagrangian Formulation ◽  
Oscillating Water Column ◽  
Extraction Chamber ◽  
Air Chamber ◽  
Air Turbine

A desingularized boundary integral equation method (DBIEM) is employed to study the wave energy extraction by an oscillating water column (OWC) device. The method is based on a mixed-Eulerian-Lagrangian formulation. We examine the effects of the relative draught on the efficiency of 2D OWC energy converters. The oscillating air pressure inside the OWC chamber is modeled by assuming that the air is incompressible and the air-turbine mass-flow rate is proportional to the pressure difference (a linear turbine). For shallow draughts the numerical results agree well with available analytical results. The wave-excited seiching inside the extraction chamber is discussed and the variation of extraction efficiency with dimensionless air-chamber width for different immersion depths is reported.

scholarly journals Air Turbines for Wave Energy Conversion

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Manabu Takao ◽  
Toshiaki Setoguchi
Keyword(s):  
Energy Conversion ◽  
Wave Energy ◽  
Cross Flow ◽  
Wave Energy Conversion ◽  
Wells Turbine ◽  
Impulse Turbine ◽  
Sea Trial ◽  
Irregular Wave ◽  
Wave Conditions ◽  
Starting Characteristics

This paper describes the present status of the art on air turbines, which could be used for wave energy conversion. The air turbines included in the paper are as follows: Wells type turbines, impulse turbines, radial turbines, cross-flow turbine, and Savonius turbine. The overall performances of the turbines under irregular wave conditions, which typically occur in the sea, have been compared by numerical simulation and sea trial. As a result, under irregular wave conditions it is found that the running and starting characteristics of the impulse type turbines could be superior to those of the Wells turbine. Moreover, as the current challenge on turbine technology, the authors explain a twin-impulse turbine topology for wave energy conversion.

Study of an Impulse Turbine for Wave Power Conversion: Effects of Reynolds Number and Hub-to-Tip Ratio on Performance

2004 ◽  
Vol 126 (2) ◽  
pp. 137-140 ◽  
Author(s):  
T. Setoguchi ◽  
M. Takao ◽  
S. Santhakumar ◽  
K. Kaneko
Keyword(s):  
Reynolds Number ◽  
Power Conversion ◽  
Critical Value ◽  
Oscillating Flow ◽  
Wave Power ◽  
Wave Energy Conversion ◽  
Flow Conditions ◽  
Impulse Turbine ◽  
Wave Power Conversion ◽  
Starting Characteristics

The objective of this paper is to report the effects of Reynolds number and hub-to-tip ratio on the performance of the impulse turbine for wave energy conversion. The turbine was investigated experimentally under steady and sinusoidally oscillating flow conditions by model testing. As a result, it was found that the critical value of Reynolds number and the optimum hub-to-tip ratio are approximately 4.0×104 and 0.7, respectively. Furthermore, their effect on starting characteristics have been clarified.

Experimental study for characteristics of slamming loads on bow of a ship-type FPSO under breaking and irregular wave conditions

2021 ◽  
Vol 224 ◽  
pp. 108738
Author(s):  
Yoon-Jin Ha ◽  
Kyong-Hwan Kim ◽  
Bo Woo Nam ◽  
Sa Young Hong ◽  
Hyunjoe Kim
Keyword(s):  
Experimental Study ◽  
Irregular Wave ◽  
Wave Conditions

Scale and Configuration Effects of an Airchamber on PTO of Oscillating Water Column Type Wave Energy Converters

2021 ◽  
Author(s):  
Tomoki Ikoma ◽  
Shota Hirai ◽  
Yasuhiro Aida ◽  
Koichi Masuda
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Water Surface ◽  
Air Pressure ◽  
Scale Model ◽  
Linear Potential ◽  
Oscillating Water Column ◽  
Wave Energy Converters ◽  
Air Chamber ◽  
Energy Converters

Abstract Wave energy converters (WECs) have been extensively researched. The behaviour of the oscillating water column (OWC) in OWC WECs is extremely complex due to the interaction of waves, air, and turbines. Several problems must be overcome before such WECs can be put to practical use. One problem is that the effect of the difference in scale between a small-scale experimental model and a full-scale model is unclear. In this study, several OWC models with different scales and geometries were used in forced oscillation tests. The wave tank was 7.0 m wide, 24.0 m long, and 1.0 m deep. In the static water experiment, we measured the air pressure and water surface fluctuations in an air chamber. For the experiments, models with a box shape with an open bottom, a manifold shape with an open bottom, and a box shape with a front opening, respectively, were fabricated. Furthermore, 1/1, 1/2, and 1/4 scale models were fabricated for each shape to investigate the effects of scale and shape on the air chamber characteristics. Numerical calculations were carried out by applying linear potential theory and the results were compared with the experimental values. The results confirmed that the air chamber shape and scale affect the air pressure fluctuation and water surface fluctuation inside the OWC system.

The Influence of Shroud and Cavity Geometry on Turbine Performance — An Experimental and Computational Study: Part II — Exit Cavity Geometry

2007 ◽  
Author(s):  
Budimir Rosic ◽  
John D. Denton ◽  
Eric M. Curtis ◽  
Ashley T. Peterson
Keyword(s):  
Computational Study ◽  
Experimental Program ◽  
Leakage Flow ◽  
Cfd Analysis ◽  
Stage Model ◽  
Low Aspect Ratio ◽  
Turbine Performance ◽  
Air Turbine ◽  
End Wall ◽  
Dominant Influence

The geometry of the exit shroud cavity where the rotor shroud leakage flow re-enters the main passage flow is very important due to the dominant influence of the leakage flow on the aerodynamics of low aspect ratio turbines. The work presented in this paper investigates, both experimentally and numerically, possibilities for the control of shroud leakage flow by modifications to the exit shroud cavity. The processes through which the leakage flow affects the mainstream aerodynamics identified in the first part of this study were used to develop promising strategies for reducing the influence of shroud leakage flow. The experimental program of this study was conducted on a three-stage model air turbine, which was extensively supported by CFD analysis. Three different concepts for shroud leakage flow control in the exit cavity were analysed and tested: a) profiled exit cavity downstream end-wall, b) axial deflector, and c) radial deflector concept. Reductions in aerodynamic losses associated with shroud leakage were achieved by controlling the position and direction at which the leakage jet re-enters the mainstream when it leaves the exit shroud cavity. Suggestions are made for an optimum shroud and cavity geometry.

The Effect of Stator-Rotor Hub Sealing Flow on the Mainstream Aerodynamics of a Turbine

2006 ◽  
Author(s):  
Kevin Reid ◽  
John Denton ◽  
Graham Pullan ◽  
Eric Curtis ◽  
John Longley
Keyword(s):  
Steady State ◽  
Entropy Generation ◽  
Flow Rate ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Flow Conditions ◽  
Turbine Efficiency ◽  
Turbine Performance ◽  
Mainstream Flow ◽  
Flow Interactions

An investigation into the effect of stator-rotor hub gap sealing flow on turbine performance is presented. Efficiency measurements and rotor exit area traverse data from a low speed research turbine are reported. Tests carried out over a range of sealing flow conditions show that the turbine efficiency decreases with increasing sealant flow rate but that this penalty is reduced by swirling the sealant flow. Results from time-accurate and steady-state simulations using a three-dimensional multi-block RANS solver are presented with particular emphasis paid to the mechanisms of loss production. The contributions toward entropy generation of the mixing of the sealant fluid with the mainstream flow and of the perturbed rotor secondary flows are assessed. The importance of unsteady stator wake/sealant flow interactions is also highlighted.

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