Effect of Guide Vane Fillets on Wave Energy Harvesting Impulse Turbine

2019 ◽  
Author(s):  
Gautam Maurya ◽  
Tapas K. Das ◽  
P. V. Dudhgaonkar ◽  
Abdus Samad
Keyword(s):  
Wave Energy ◽  
Guide Vane ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Impulse Turbine ◽  
Navier Stokes Equation ◽  
Ansys Cfx ◽  
Commercial Code ◽  
Water Columns ◽  
Oscillating Water Columns

Abstract Oscillating water columns (OWC) are widely used devices for the extraction of wave energy through self -rectifying impulse air turbines. To improve the performance of any turbo-machinery, guide vanes (GV) play an essential role in deciding turbine characteristics in terms of efficiency and torque. The concept of filleting is used in the GVs of bidirectional impulse turbine (BDI) with five different types of GV fillets for different radii, and the performance was analyzed. The numerical simulation was done using the commercial code ANSYS CFX 16.2, which solves the three-dimensional Reynolds-Averaged Navier-Stokes equation by finite volume explicit Runge-Kutta scheme with the k-ω SST closure model. There is a close agreement between the experimental and the numerical model. The detailed flow physics of filleted GVs have been included in the present work, and it was found that the efficiency increases at higher flow coefficients.

scholarly journals Effect of Blade Profiles on the performance of Bidirectional Wave Energy Turbine

2018 ◽  
Vol 172 ◽  
pp. 06002
Author(s):  
P.Madhan Kumar ◽  
Abdus Samad
Keyword(s):  
Wave Energy ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Wells Turbine ◽  
Reference Case ◽  
Navier Stokes Equation ◽  
World Energy ◽  
Entrapped Air ◽  
Experimental Values

To fulfill the ever growing demands of world energy consumption, the wave energy should be extracted economically. The oscillating water column is most commonly used to xtract energy from waves. It consists of a chamber in which waves drives the entrapped air column to rotate the Wells turbine. The Wells turbine is a self-rectifying low-pressure axial reaction turbine with 90ο stagger angle. These turbines consist of symmetrical airfoil profile to achieve unidirectional rotation for the bi-directional airflow. The turbine performance predominantly depends on the aerodynamic characteristics of the airfoil profile used. In this study, the performance of Wells turbine with various symmetrical airfoil profiles was analysed using ANSYS CFX 14.5. The CFD analysis was performed by solving three dimensional steady Reynolds averaged Navier-Stokes equation with k-ω SST turbulence closure model. The reference geometry has NACA0015 as blade profile and the CFD results were compared with the experimental values. The performance characteristics of the new airfoil profiles were compared with the reference case to analyse the suitability of airfoils in wave energy extraction. The NACA0021 airfoil profile showed better performance in the post-stall regime compared to the NACA0015 and the S1046 airfoil profiles.

Numerical Study on the Flow Characteristics of the Francis Turbine With Various Blade Profiles

2013 ◽  
Author(s):  
J.-H. Jeon ◽  
S.-S. Byeon ◽  
Y.-J. Kim
Keyword(s):  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Francis Turbine ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Ansys Cfx ◽  
Commercial Code ◽  
Sst Turbulence Model

The Francis turbine is a kind of reaction turbines, which means that the potential energy of water converted to rotational kinetic energy. In this study, the flow characteristics have been investigated numerically in a Francis turbine on the 15 MW hydropower generation with various blade profiles (NACA 65 and NACA 16 series) and discharge angles (14°, 15°, 17°, and 18°), using the commercial code, ANSYS CFX. The k-ω SST turbulence model is employed in the Reynolds averaged Navier-Stokes equations. The computing domain includes the spiral casing, guide vanes, and draft tube, which are discretized with a full three-dimensional mesh system of unstructured tetrahedral shapes. The results showed that the change of blade profiles and discharge angles significantly influenced the performance of the Francis turbine.

Nature-inspired design of a turbine blade harnessing wave energy

2019 ◽  
Vol 234 (5) ◽  
pp. 670-689 ◽  
Author(s):  
P Madhan Kumar ◽  
Abdus Samad
Keyword(s):  
Wave Energy ◽  
Suction Side ◽  
Navier Stokes ◽  
Trailing Edge ◽  
Navier Stokes Equation ◽  
Ansys Cfx ◽  
Grid Convergence ◽  
Computational Fluid Dynamics Cfd ◽  
Grid Convergence Index ◽  
Increased Pressure

A bidirectional turbine used in an oscillating water column device extracts wave energy from oscillating airflow. To improve its power output, a concept of static extended trailing edge found in the wings of owl and merganser was adopted. The static extended trailing edge with 0–10% of chord length ( C) was analyzed for different flow coefficients via Reynolds-averaged Navier–Stokes equation-based computational fluid dynamics (CFD) analysis. ANSYS-CFX 15.0 was used to simulate the flow. Grid convergence index was calculated to obtain optimum mesh, and numerical validation was done with experimental results. The static extended trailing edge with 5% C enhanced relative mean torque by 23.4% and, reduced relative mean efficiency by 5.4%, before stall condition. The modification increased pressure difference between the suction side and the pressure side and enhanced torque. The increased pressure drop reduced the efficiency. A further longer static extended trailing edge showed poorer stall characteristics.

High-performance ocean energy harvesting turbine design – Detailed flow analysis with blade leaning strategy

2018 ◽  
Vol 233 (3) ◽  
pp. 379-396 ◽  
Author(s):  
B Ranjith ◽  
Paresh Halder ◽  
Abdus Samad
Keyword(s):  
High Performance ◽  
Guide Vane ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Internal Flow ◽  
Principal Component ◽  
Geometrical Parameters ◽  
Impulse Turbine ◽  
Navier Stokes Equation ◽  
Low Efficiency

Oscillating water column wave energy converter is having low efficiency because of its principal component, a bidirectional turbine. An analysis of the internal flow of the turbine gives an idea of improving the performance through optimization of geometrical parameters. In this study, an impulse turbine of 0.3 m diameter with fixed guide vanes is numerically simulated by solving three-dimensional incompressible steady Reynolds averaged Navier-stokes equation with two-equation turbulence closure model. This study shows that the numerical results very well match with the experimental results. The detailed flow physics demonstrates that different types of losses occur in this type of turbine and shows that the downstream diverging path of the rotor and guide vane is responsible for low performance. In this study, the effect of guide vane lean, as well as the combined rotor and guide vane lean on the performance of the turbine, has been discussed in detail and found to increase the efficiency of the turbine.

The Extension of a Solution-Adaptive Three-Dimensional Navier–Stokes Solver Toward Geometries of Arbitrary Complexity

1993 ◽  
Vol 115 (2) ◽  
pp. 283-295 ◽  
Author(s):  
W. N. Dawes
Keyword(s):  
Guide Vane ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Centrifugal Impeller ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Wide Range ◽  
Nozzle Guide Vane ◽  
Recent Developments ◽  
Nozzle Guide

This paper describes recent developments to a three-dimensional, unstructured mesh, solution-adaptive Navier–Stokes solver. By adopting a simple, pragmatic but systematic approach to mesh generation, the range of simulations that can be attempted is extended toward arbitrary geometries. The combined benefits of the approach result in a powerful analytical ability. Solutions for a wide range of flows are presented, including a transonic compressor rotor, a centrifugal impeller, a steam turbine nozzle guide vane with casing extraction belt, the internal coolant passage of a radial inflow turbine, and a turbine disk cavity flow.

On the Array of Wave Energy Converters: The Case of the Coaxial-Duct OWC

2018 ◽  
Author(s):  
J. C. C. Portillo ◽  
J. C. C. Henriques ◽  
R. P. F. Gomes ◽  
L. M. C. Gato ◽  
A. F. O. Falcão
Keyword(s):  
Wave Energy ◽  
Oscillating Water Column ◽  
Economic Activities ◽  
Energy Converter ◽  
Diverse Range ◽  
Wave Energy Converters ◽  
Large Size ◽  
New Findings ◽  
Water Columns ◽  
Oscillating Water Columns

This work focuses on the initial performance assessment of an array of coaxial-duct (CD) oscillating-water-columns (owc’s) with potential to be used as multipurpose platform for the creation of value in a diverse range of offshore economic activities. The coaxial-duct owc (CD-owc) is an axisymmetric oscillating-water-column wave energy converter that has been studied for both small-size and large-size applications. This work focuses on buoys of 12 meter diameter distributed in an array of five devices, rigidly attached to each other, to form a cluster of owc’s. The objective of the study is to assess the performance of the array with this configuration and estimate the effect of parameters such as distance between devices, various modes of movements, and other constraints on the overall power output of the array. Results of different cases are compared to the performance of an isolated device to determine the interference effect of other devices. Some results validate previous research conclusions and new findings on the behavior coaxial-duct owc are presented.

Cylinder rolling on a wall at low Reynolds numbers

2011 ◽  
Vol 685 ◽  
pp. 461-494 ◽  
Author(s):  
Alain Merlen ◽  
Christophe Frankiewicz
Keyword(s):  
Three Dimensional ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Flow Around A Cylinder ◽  
Low Reynolds Numbers ◽  
Initial Location ◽  
Upstream Pressure ◽  
Small Reynolds Numbers ◽  
Onset Of Cavitation

AbstractThe flow around a cylinder rolling or sliding on a wall was investigated analytically and numerically for small Reynolds numbers, where the flow is known to be two-dimensional and steady. Both prograde and retrograde rotation were analytically solved, in the Stokes regime, giving the values of forces and torque and a complete description of the flow. However, solving Navier–Stokes equation, a rotation of the cylinder near the wall necessarily induces a cavitation bubble in the nip if the fluid is a liquid, or compressible effects, if it is a gas. Therefore, an infinite lift force is generated, disconnecting the cylinder from the wall. The flow inside this interstice was then solved under the lubrication assumptions and fully described for a completely flooded interstice. Numerical results extend the analysis to higher Reynolds number. Finally, the effect of the upstream pressure on the onset of cavitation is studied, giving the initial location of the phenomenon and the relation between the upstream pressure and the flow rate in the interstice. It is shown that the flow in the interstice must become three-dimensional when cavitation takes place.

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