A Study on the Effects of Blade Profile and Non-Uniform Tip Clearance of the Wells Turbine

2008 ◽  
Author(s):  
Manabu Takao ◽  
Toshiaki Setoguchi ◽  
Shuichi Nagata ◽  
Kazutaka Toyota
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Flow Condition ◽  
Rotor Blade ◽  
Tip Clearance ◽  
Blade Profile ◽  
Wells Turbine ◽  
Energy Devices ◽  
Air Turbine ◽  
Air Column

Several of wave energy devices being studied under many wave energy programs in the United Kingdom, Japan, Portugal, India and other countries make use of the principle of an oscillating water column (OWC). In such wave energy devices, a water column which oscillates due to wave motion is used to drive an oscillating air column which is converted into mechanical energy. The energy conversion from the oscillating air column can be achieved by using a self-rectifying air turbine. Wells turbine is a self-rectifying air turbine which is expected to be widely used in wave energy devices with OWC. There are many reports which describe the performance of Wells turbine both at starting and running characteristics. According to these results, Wells turbine has inherent disadvantages: lower efficiency, poorer starting and higher noise level in comparison with conventional turbines. In order to enhance the performance of Wells turbine, some rotor blade profiles have been recommended by various researchers. The aim of this study is to investigate the effect of rotor blade profile on the performance of Wells turbine. In the study, four kinds of blade profile were selected and tested by model testing under steady flow condition. The types of blade profile are as follows: NACA0020; NACA0015; modified NACA0015; and modified Eppler472. The experimental investigations have been performed by use of test section with a casing diameter of 300 mm. Further, the effect of non-uniform tip clearance on the turbine performance was tested and the result was compared with that of the case of Wells turbine with uniform tip clearance. As an additional experiment, the effects of blade profile and non-uniform tip clearance on the performance under unsteady flow condition have been investigated numerically by using a quasi-steady analysis.

A Methodology for Wells Turbine Design for Wave Energy Conversion

1995 ◽  
Vol 209 (3) ◽  
pp. 221-232 ◽  
Author(s):  
S Raghunathan
Keyword(s):  
Wave Energy ◽  
Mechanical Energy ◽  
Aerodynamic Design ◽  
Wave Energy Conversion ◽  
Wells Turbine ◽  
Single Plane ◽  
Energy Devices ◽  
The United Kingdom ◽  
Air Turbine ◽  
Turbine Design

The wave energy devices currently being built in the United Kingdom and elsewhere have adopted the Wells air turbine for converting pneumatic energy in the device to mechanical energy of rotation. A monoplane (single-plane) Wells turbine can operate efficiently over a certain maximum flowrate and pneumatic pressure drop due to blade stall and tip speed limitations respectively. The knowledge base on the monoplane Wells turbine is reviewed. An interactive methodology for an aerodynamic design of this turbine is presented.

Analysis of the Wells Turbine Structure of an Oscillating Water Column Wave Energy System

2021 ◽  
pp. 53-62
Author(s):  
Mohamed Ali Jemni ◽  
Hamdi Hentati ◽  
Sawsan Elmbarki ◽  
Mohamed Salah Abid
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Energy System ◽  
Oscillating Water Column ◽  
Wells Turbine

The Development and Testing of a Wave-Activated Navigation Buoy With a Wells Turbine

1985 ◽  
Vol 107 (2) ◽  
pp. 268-273 ◽  
Author(s):  
T. J. T. Whittaker ◽  
F. A. McPeake ◽  
A. G. Barr
Keyword(s):  
Water Column ◽  
Peak Performance ◽  
Optimum Level ◽  
Wells Turbine ◽  
Turbine Generator ◽  
Ongoing Research ◽  
Air Turbine ◽  
Hydrodynamic Response ◽  
Current Design ◽  
Heave Motion

This paper presents and discusses the results of the first stage of an ongoing research program to improve the design of wave powered navigation aids using the oscillating water column principle. Wave tank testing has shown that the heave motion of current tail tube buoys is the predominant feature of the hydrodynamic response. A Wells self rectifying air turbine, coupled to a 100-W generator which produces an optimum level of damping to the water column for peak performance, has been designed and tested. It has been concluded from preliminary sea trails that a simple, efficient, reliable, turbine-generator has been developed to meet the requirements of the current design of navigation buoy. However there is considerable scope for improving the hydrodynamic design of wave activated buoys.

Experimental Study of a Radial Turbine Using Floating Nozzle for Wave Energy Conversion

2009 ◽  
Author(s):  
Toshio Konno ◽  
Yoshihiro Nagata ◽  
Manabu Takao ◽  
Toshiaki Setoguchi
Keyword(s):  
Energy Conversion ◽  
Steady Flow ◽  
Wave Energy ◽  
Flow Condition ◽  
Radial Flow ◽  
Guide Vane ◽  
Wave Energy Conversion ◽  
Wells Turbine ◽  
Radial Turbine ◽  
Steady Flow Condition

The objective of this study is to propose a new radial flow turbine for wave energy conversion and to clarify its performance by model testing under steady flow condition. The proposed radial turbine has a rotor blade row for unidirectional airflow and two guide vane rows. The guide vane rows are named ‘floating nozzle’ in the study. The guide vane rows slide in an axial direction and work as nozzle in the turbine alternately for bi-directional airflow, so as to rectify bidirectional airflow and to make uni-directional airflow. The radial flow turbine with a diameter of 500mm has been manufactured and investigated experimentally under steady flow condition generated by a wind tunnel using a piston/cylinder system with a diameter of 1.4m. As a result, it has been found in the study that the peak efficiency of the proposed radial turbine is approximately 57% and the rotational speed of this turbine is considerably lower that that of Wells turbine. Further, the effect of nozzle setting angle on the turbine performance was investigated and clarified in the study.

Overview on Oscillating Water Column Devices

2022 ◽  
Author(s):  
A.F.O. Falcão
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Important Class ◽  
Oscillating Water Column ◽  
Energy Converter ◽  
Energy Devices ◽  
New Concepts ◽  
Testing Techniques ◽  
Fixed Structure ◽  
And Control

Abstract. Oscillating-water-column (OWC) converters, of fixed structure or floating, are an important class of wave energy devices. A large part of wave energy converter prototypes deployed so far into the sea are of OWC type. The paper presents a review of recent advances in OWC technology, including sea-tested prototypes and plants, new concepts, air turbines, model testing techniques and control.

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