A Comparison of Self-Rectifying Turbines for OWC Based Wave Energy Power Extracting Device Using Numerical Simulation

2002 ◽  
Author(s):  
A. R. Ansari ◽  
H. B. Khaleeq ◽  
A. Thakker
Keyword(s):  
Numerical Simulation ◽  
Wave Energy ◽  
Sea Water ◽  
Time History ◽  
Flow Conditions ◽  
Wells Turbine ◽  
Impulse Turbine ◽  
Simulation Techniques ◽  
Simple Geometry ◽  
Wide Range

This paper presents a comparison of self-rectifying turbines for the Oscillating Water Column (OWC) based Wave Energy power extracting device using numerical simulation. The two most commonly used turbines for OWC based devices, the Impulse and the Wells turbines were evaluated under real sea simulated conditions. Assuming the quasi-steady condition, experimental data for both 0.6m turbines with 0.6 hub to tip ratio was used to predict their behavior under real sea conditions. The real sea water surface elevation time history data was used to simulate the flow conditions using standard numerical simulation techniques. A simple geometry of the OWC was considered for the simulation. The results show that the overall mean performance of an Impulse turbine is better than the Wells turbine under unsteady, irregular real sea conditions. The Impulse turbine was observed to be more stable over a wide range of flow conditions. This paper reports the comparison of performance characteristics of both these turbines under simulated real sea conditions.

scholarly journals Surface contamination of cars: A review

2017 ◽  
Vol 231 (9) ◽  
pp. 1160-1176 ◽  
Author(s):  
Adrian P Gaylard ◽  
Kerry Kirwan ◽  
Duncan A Lockerby
Keyword(s):  
Numerical Simulation ◽  
Surface Water ◽  
Automotive Industry ◽  
Test Methods ◽  
Surface Contamination ◽  
Front Side ◽  
Water Droplets ◽  
Simulation Techniques ◽  
Wide Range ◽  
Safety Systems

This review surveys the problem of surface contamination of cars, which poses a growing engineering challenge to vehicle manufacturers, operators and users. Both the vision of drivers and the visibility of vehicles need to be maintained under a wide range of environmental conditions. This requires managing the flow of surface water on windscreens and side glazing. The rate of deposition of solid contaminants on glazing, lights, licence plates and external mirrors also needs to be minimised. Maintaining vehicle aesthetics and limiting the transfer of contaminants to the hands and clothes of users from soiled surfaces are also significant issues. Recently, keeping camera lenses clean has emerged as a key concern, as these systems transition from occasional manoeuvring aids to sensors for safety systems. The deposition of water and solid contaminants on to car surfaces is strongly influenced by unsteady vehicle aerodynamic effects. Airborne water droplets falling as rain or lifted as spray by tyres interact with wakes, vortices and shear flows and accumulate on vehicle surfaces as a consequence. The same aerodynamic effects also control the movement of surface water droplets, rivulets and films; hence, particular attention is paid to the management of surface water over the front side glass and the deposition of contaminants on the rear surfaces. The test methods used in the automotive industry are reviewed, as are the numerical simulation techniques.

scholarly journals Effects of Compressibility on the Performance of a Wave-Energy Conversion Device with an Impulse Turbine Using a Numerical Simulation Technique

2003 ◽  
Vol 9 (6) ◽  
pp. 443-450 ◽  
Author(s):  
A. Thakker ◽  
T. S. Dhanasekaran ◽  
M. Takao ◽  
T. Setoguchi
Keyword(s):  
Numerical Technique ◽  
Time History ◽  
Wave Climate ◽  
Simulation Technique ◽  
Flow Conditions ◽  
Impulse Turbine ◽  
Compressibility Effect ◽  
Time Period ◽  
Air Chamber ◽  
The Mean

This article presents work carried out to predict the behavior of a 0.6 m impulse turbine with fixed guide vanes as compared with that of a 0.6 hub-to-tip ratio turbine under real sea conditions. In order to predict the true performance of the actual oscillating water column (OWC), the numerical technique was fine-tuned by incorporating the compressibility effect. Water surface elevation versus time history was used as the input data for this purpose. The effect of compressibility inside the air chamber and the turbine's performance under unsteady and irregular flow conditions were analyzed numerically. Considering the quasi-steady assumptions, the unidirectional steady-flow experimental data was used to simulate the turbines characteristics under irregular unsteady flow conditions. The results showed that the performance of this type of turbine is quite stable and that the efficiency of the air chamber and the mean conversion efficiency are reduced by around 8% and 5%, respectively, as a result of the compressibility inside the air chamber. The mean efficiencies of the OWC device and the impulse turbine were predicted for 1 month, based on the Irish wave climate, and it was found that the total time period of wave data used is one of the important factors in the simulation technique.

scholarly journals Optimal design of air turbines for oscillating water column wave energy systems: A review

2017 ◽  
Vol 8 (1) ◽  
pp. 37-49 ◽  
Author(s):  
Tapas Kumar Das ◽  
Paresh Halder ◽  
Abdus Samad
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Guide Vane ◽  
Optimization Techniques ◽  
Maximum Efficiency ◽  
Oscillating Water Column ◽  
Peak Efficiency ◽  
Wells Turbine ◽  
Impulse Turbine ◽  
Operating Range

Oscillating water column wave energy harvesting system uses pneumatic power to run a turbine and generate power. Both reaction (mainly Wells turbine) and impulse type turbines are tested in oscillating water column system and the performances are investigated. Reaction turbines are easy to install, and the operating range is narrow and possesses higher peak efficiency. On the contrary, impulse turbines have the wider operating range and lower peak efficiency. Some of the key parameters for Wells turbine are solidity, tip clearance, and the hub-to-tip ratio. Significant performance improvement is possible by redesigning the turbines using optimization techniques. Till date, surrogate modeling and an automated optimization library OPAL are commonly used in optimization of oscillating water column air turbines. In this article, various types of oscillating water column turbines are reviewed, and optimization techniques applied to such turbines are discussed. The Wells turbine with guide vane has the maximum efficiency, whereas the axial-impulse turbine with pitch-controlled guide vane has the widest operating range. Turbines with optimized geometry have better overall performance than other turbines.

Effect of End Plates on the Performance of an Impulse Turbine for Wave Energy Conversion

2007 ◽  
Author(s):  
Toshiaki Setoguchi ◽  
Manabu Takao ◽  
Kenji Kaneko ◽  
Shuichi Nagata ◽  
Kazutaka Toyota
Keyword(s):  
Experimental Investigation ◽  
Energy Conversion ◽  
Steady Flow ◽  
Wave Energy ◽  
Model Testing ◽  
Wave Energy Conversion ◽  
Flow Conditions ◽  
Impulse Turbine ◽  
End Plate ◽  
Plate Size

The objective of this paper is to present the effect of end plate on the performances of the impulse turbine for wave energy conversion by experimental investigation. The experiments have been performed by model testing under steady flow conditions in the study. And then, the performances of the impulse turbine with end plates have been compared with those of the original impulse turbine, i.e., the impulse turbine without end plate. As a result, it is found that the characteristics of the impulse turbine with end plates are superior to those of the original impulse turbine. Furthermore, the effects of end plate size and penetration on the turbine characteristics have been clarified in the study.

Application of numerical simulation method to predict the performance of wave energy device with impulse turbine

2003 ◽  
Vol 12 (1) ◽  
pp. 38-43 ◽  
Author(s):  
Ajit Thakker ◽  
Thirumalisai Dhanasekaran ◽  
Hammad Khaleeq ◽  
Zia Usmani ◽  
Ali Ansari ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Wave Energy ◽  
Simulation Method ◽  
Impulse Turbine ◽  
Energy Device ◽  
Numerical Simulation Method

Experimental Study on a Twin Unidirectional Impulse Turbine for Wave Energy Conversion

2011 ◽  
Author(s):  
Manabu Takao ◽  
Md. Mahbubu Alam ◽  
Toshiaki Setoguchi ◽  
V. Jayashankar
Keyword(s):  
Experimental Study ◽  
Wind Tunnel ◽  
Wave Energy ◽  
Flow Direction ◽  
Wave Energy Conversion ◽  
Flow Conditions ◽  
Impulse Turbine ◽  
Piston Cylinder ◽  
Energy Plant ◽  
Large Piston

A twin unidirectional impulse turbine has been proposed in order to enhance the performance of wave energy plant. This turbine system uses two unidirectional impulse turbines and their flow direction is different each other. However, the turbine characteristics have not been clarified to date. The performances of a unidirectional impulse turbine under steady flow conditions were investigated experimentally by using a wind tunnel with large piston/cylinder in this study.

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