Numerical Prediction of the Hydrodynamic Performance of a Horizontal Tidal Turbines

2015 ◽  
Author(s):  
Cheng Liu ◽  
Changhong Hu
Keyword(s):  
Power Efficiency ◽  
Turbulence Models ◽  
Hydrodynamic Performance ◽  
Navier Stokes ◽  
Renewable Energy Resources ◽  
Tidal Current Energy ◽  
Tidal Turbines ◽  
Critical Issues ◽  
Tidal Turbine ◽  
Sst Turbulence Model

Tidal current energy is one of the most promising renewable energy resources. The prediction of the hydrodynamic loads and power efficiency are the critical issues for verifying the new designs. Besides, Optimization of turbine arrangement is important for a tidal turbine farm. The hydrodynamic behavior of a turbine operating in the wake of an upstream turbine needs to clarify. In this paper we present a CFD approach in which the CFD library of OpenFOAM is utilized for prediction of the performance of a three bladed horizontal axis tidal turbine (HATT) in a test tunnel environment. The Reynolds Average Navier Stokes (RANS) equation with Shear Stress Transport (SST) turbulence model is applied. The steady-state solver is tested for present numerical simulation. The Multi Reference Framework (MRF) method is adopted for dealing with grid relative rotation. Turbulence models effects and the mesh generation are well described. The resultant power and thrust coefficients of these simulations are compared with experimental results at various tip speed ratios (TSRs).

Numerical Investigation of an Optimised Horizontal Axis Tidal Stream Turbine

2019 ◽  
Author(s):  
Hassan El Sheshtawy ◽  
Ould el Moctar ◽  
Thomas E. Schellin ◽  
Satish Natarajan
Keyword(s):  
Output Power ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Speed Ratio ◽  
Navier Stokes Equations ◽  
Tidal Turbines ◽  
Tidal Turbine ◽  
Sst Turbulence Model ◽  
Tidal Stream ◽  
Tidal Stream Turbine

Abstract A tidal stream turbine was designed using one of the optimised hydrofoils, whose lift-to-drag ratio at an angle of attack of 5.2 degrees was 4.5% higher than that of the reference hydrofoil. The incompressible Reynolds-averaged Navier Stokes equations in steady state were solved using k-ω (SST) turbulence model for the reference and optimised tidal stream turbines. The discretisation errors and the effect of different y+ values on the solution were analysed. Thrust and power coefficients of the modelled reference turbine were validated against experimental measurements. Output power and thrust of the reference and the optimised tidal turbines were compared. For a tip speed ratio of 3.0, the output power of the optimised tidal turbine was 8.27% higher than that of the reference turbine of the same thrust.

scholarly journals The effects of surge motion on floating horizontal axis tidal turbines

2020 ◽  
Vol 3 (2) ◽  
pp. 45-54
Author(s):  
Mohamad Osman ◽  
Richard H. J. Willden ◽  
Christopher R. Vogel
Keyword(s):  
Reference Frame ◽  
Rotational Frequency ◽  
Horizontal Axis ◽  
Hydrodynamic Performance ◽  
Navier Stokes ◽  
Speed Ratio ◽  
Navier Stokes Equation ◽  
Tidal Turbine ◽  
Sst Turbulence Model ◽  
Wave Induced

Wave induced motions due to actual sea state conditions will impact the performance of floating horizontal axis tidal turbine systems. This paper presents the results from numerical simulations of a 3-bladed horizontal axis tidal turbine oscillating in surge motion in a moving reference frame. The optimum tip-speed ratio, λ = 4.4 and k-ω SST turbulence model were used in the present study. The Navier-Stokes equation was modified by adding an inertial term to the equation and the Dirichlet boundary condition was also modified in order to simulate in the moving reference frame. The surge oscillations were parameterised in terms of the ratio of surge amplitude to rotor radius, A*, and the ratio of oscillation frequency to the rotational frequency of the rotor, ω*. A series of tests were conducted to study the effect of each parameter on the hydrodynamic performance of the tidal turbine. The results show that stall can occur on the blade when the velocity relative to the rotor is sufficiently high. In certain cases, negative thrust and power coefficients were observed when the velocity relative to the rotor is low. The fluctuation in blade loading increases together with the amplitude and frequency of oscillation, which will contribute to the fatigue of the rotor.

Modelling the wake of a tidal turbine with upstream turbulence

2020 ◽  
Vol 3 (2) ◽  
pp. 83-89
Author(s):  
Mikaël Grondeau ◽  
Jean-Charles Poirier ◽  
Sylvain Guillou ◽  
Yann M´ear ◽  
Philippe Mercier ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Lattice Boltzmann ◽  
Navier Stokes ◽  
Eddy Simulation ◽  
Tidal Turbines ◽  
Large Eddy ◽  
Tidal Turbine ◽  
Good Concordance ◽  
Ambient Turbulence ◽  
Boltzmann Method

Tidal turbines are entering an industrial phase and farms will soon be installed. In order to optimize the power output of tidal farms, a good understanding of the interactions between the ambient turbulence and a single turbine is crucial. Computational Fluid Dynamics, and more precisely Large Eddy Simulation, is one way of acquiring such knowledge. This study proposed a comparison between a Lattice Boltzmann Method LES approach and a Navier-Stokes LES approach to model the wake of a tidal turbine. Numerical results are compared with experimental results and a relatively good concordance is observed. Differences inherent to the approaches are then pointed out.

Experimental study of the duct-effects of the tidal current turbines in multi-row-staggered layout

2020 ◽  
Author(s):  
Yaling Chen ◽  
Binliang Lin ◽  
Jinxi Guo
Keyword(s):  
Tidal Current ◽  
Turbine Rotor ◽  
Power Performance ◽  
Tidal Current Energy ◽  
Tidal Turbines ◽  
Initial Stage ◽  
Tidal Turbine ◽  
Wake Zone ◽  
The Stability ◽  
Current Energy

<p>Tidal turbine array was optimized to increase the power production in order to improve the commercial competitivity of tidal current energy with other forms of energy generation. Due to duct-effects, the power performance of turbines in the staggered layout was better than that of the aligned layout. However, shear layer with enhanced turbulence occurred between the duct zone and isolated wake zone downstream, which had influence on the performance stability and increased the fatigue failure of tidal turbines. The study conducted a series of laboratory experiments to investigate the duct-effects of tidal turbines located in multi-row array with staggered layout. The turbine rotor was represented by porous disc. The flow thrust and time-varying velocity were measured using micro strain gauge and acoustic doppler velometer, respectively. Results showed that the flow was accelerated between turbines with the increment around 20% behind the first row, while the duct-effects were weakened as distance increased downstream. The shear-induced turbulence was enlarged by the duct-effect when it diffused mainly towards individual wake zone at the initial stage. As the turbulence filled the whole individual wake zones, it diffused rapidly to lateral sides and jointed together, and the turbulence intensity across the array wake was significantly higher than that of the free flow. Correspondingly, the performance of turbine rotor located downstream was improved limitedly by the duct-effects, and the stability was reduced clearly. It indicated that the advantage of the duct-effect induced in the staggered layout was limited in the near wake as the lateral interval between two turbine centres was 2 times of rotor diameter.</p><p>Keywords<strong>:</strong> Turbine rotor array; Staggered layout; Duct-effects; Turbine performance; Shear-induced turbulence</p>

Development of a Numerical Based Correlation for Performance Losses due to Surface Roughness in Axial Turbines

2014 ◽  
Vol 30 (6) ◽  
pp. 631-642 ◽  
Author(s):  
S. A. Moshizi ◽  
M. H. Nakhaei ◽  
M. J. Kermani ◽  
A. Madadi
Keyword(s):  
Turbulence Model ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Streamline Curvature ◽  
Sst Turbulence Model ◽  
Stator Blade ◽  
Dimensional Models ◽  
Three Dimensional Models ◽  
Axial Turbines

AbstractIn the present work, a recently developed in-house 2D CFD code is used to study the effect of gas turbine stator blade roughness on various performance parameters of a two-dimensional blade cascade. The 2D CFD model is based on a high resolution flux difference splitting scheme of Roe (1981). The Reynolds Averaged Navier-Stokes (RANS) equations are closed using the zero-equation turbulence model of Baldwin-Lomax (1978) and two-equation Shear Stress Transport (SST) turbulence model. For the smooth blade, results are compared with experimental data to validate the model. Finally, a correlation between roughness Reynolds number and loss coefficient for both turbulence models is presented and tested for three other roughness heights. The results of 2D turbine blade cascades can be used for one-dimensional models such as mean line analysis or quasi-three-dimensional models e.g. streamline curvature method.

Tidal Turbine Blade Selection for Optimal Performance in an Array

2011 ◽  
Author(s):  
Rachel F. Nicholls-Lee ◽  
Stephen R. Turnock ◽  
Stephen W. Boyd
Keyword(s):  
Tidal Cycle ◽  
Free Stream ◽  
Stokes Equations ◽  
Tidal Energy ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Energy Capture ◽  
Tidal Turbines ◽  
Outer Domain ◽  
Tidal Turbine

In order to maximize tidal energy capture from a specific site free stream devices are situated in arrays. In an array the downstream evolution of the wake generated by a rotating tidal energy conversion device influences the performance of the device itself, the bypass flow to either side as well as the performance of any downstream device. As such it is important to design a turbine that can perform efficiently and effectively in these circumstances. Use of passively adaptive composite blades for horizontal axis tidal turbines has been shown to improve performance in fluctuating inflows. Active adaptation and/or bi-directional hydrofoil sections could be implemented in order to optimize performance throughout the tidal cycle. This paper considers the performance in an array of four free stream turbines implementing standard rigid blades, wholly bidirectional blades, passively adaptive blades and actively adaptive blades. The method used to evaluate the performance of tidal current turbines in arrays couples an inner domain solution of the blade element momentum theory with an outer domain solution of the Reynolds averaged Navier Stokes equations. The annual energy capture of four devices with each blade type in a staggered array is then calculated for a single tidal cycle and compared.

scholarly journals An Unsteady Boundary Element Model for Hydrodynamic Performance of a Multi-Blade Vertical-Axis Tidal Turbine

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1413 ◽  
Author(s):  
Guangnian Li ◽  
Qingren Chen ◽  
Hanbin Gu
Keyword(s):  
Boundary Element ◽  
Numerical Solutions ◽  
Vertical Axis ◽  
Element Model ◽  
Hydrodynamic Performance ◽  
Design And Optimization ◽  
Tidal Turbines ◽  
Proposed Model ◽  
Tidal Turbine ◽  
Vertical Axis Tidal Turbine

An unsteady boundary element model is developed to simulate the unsteady flow induced by the motion of a multi-blade vertical axis turbine. The distribution of the sources, bound vortices and wake vortices of the blades are given in detail. In addition, to make the numerical solution more robust, the Kutta condition is also introduced. The developed model is used to predict the hydrodynamic performance of a vertical axis tidal turbine and is validated by comparison with experimental data and other numerical solutions available in the literature. Good agreement is achieved and the calculation of the proposed model is simpler and more efficient than prior numerical solutions. The proposed model shows its capability for future profile design and optimization of vertical axis tidal turbines.

Comprehensive Study on Variable Pitch Vertical Axis Tidal Turbine

2012 ◽  
Vol 229-231 ◽  
pp. 778-782 ◽  
Author(s):  
Khalid Syed Shah ◽  
Liang Zhang
Keyword(s):  
Vertical Axis ◽  
Turbine Rotor ◽  
Hydrodynamic Performance ◽  
Navier Stokes ◽  
Design Parameters ◽  
Ongoing Research ◽  
Variable Pitch ◽  
Main Challenge ◽  
Tidal Turbine ◽  
Vertical Axis Tidal Turbine

To overcome the stalled effect and poor starting torque of fixed pitch Darrieus turbine, researchers invent variable pitch vertical axis tidal turbine (VATT). For tidal stream designers main challenge is that the design can sustain in hostile marine environment. Due to lift base design VATT is very critical for cavitation, so appropriate parameter selection can improve the hydrodynamic performance and life of the turbine. An attempt is made to optimize the design parameters of VATT for variable pitch using ANSYS CFX, hereafter CFX, which is based on a Reynolds-Averaged Navier-Stokes (RANS) model. A transient simulation is done for variable pitch VATT using Shear Stress Transport turbulence (SST) scheme. Main hydrodynamic parameters like torque T, combined moment CM, coefficients of performance CP and coefficient of torque CT, etc. are investigated. The modeling and meshing of turbine rotor is performed in ICEM-CFD. Mesh motion option is employed to achieve variable pitch phenomenon. This article is the one part of the ongoing research on turbine design and developments. The numerical simulation results are validated with analytical Matlab results performed by Edinburgh Design Ltd. The article concludes that CFX simulation is done accurately and major parameter selections for turbine development are feasible.

scholarly journals Study of Hydrodynamic Interference of Vertical-Axis Tidal Turbine Array

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1228
Author(s):  
Guangnian Li ◽  
Qingren Chen ◽  
Hanbin Gu
Keyword(s):  
Vertical Axis ◽  
Tidal Energy ◽  
Element Model ◽  
Hydrodynamic Performance ◽  
Maximum Efficiency ◽  
Hydrodynamic Characteristics ◽  
Tidal Turbines ◽  
Tidal Turbine ◽  
Vertical Axis Turbine ◽  
Vertical Axis Tidal Turbine

The hydrodynamic interference between tidal turbines must be considered when predicting their overall hydrodynamic performance and optimizing the layout of the turbine array. These factors are of great significance to the development and application of tidal energy. In this paper, the phenomenon of hydrodynamic interference of the tidal turbine array is studied by the hydrodynamic performance forecast program based on an unsteady boundary element model for the vertical-axis turbine array. By changing the relative positions of two turbines in the double turbine array to simulate the arrangement of different turbines, the hydrodynamic interference law between the turbines in the array and the influence of relative positions on the hydrodynamic characteristics in the turbine array are explored. The manner in which the turbines impact each other, the degree of influence, and rules for turbine array arrangement for maximum efficiency of the array will be discussed. The results of this study will provide technical insights to relevant researchers.

Numerical Simulation of Marine Propeller Hydrodynamic Performance in Uniform Inflow with Different Turbulence Models

2013 ◽  
Vol 389 ◽  
pp. 1019-1025 ◽  
Author(s):  
Mohamed Bennaya ◽  
Jing Feng Gong ◽  
Moutaz M. Hegaze ◽  
Wen Ping Zhang
Keyword(s):  
Turbulence Model ◽  
Turbulence Models ◽  
Open Water ◽  
Hydrodynamic Performance ◽  
Navier Stokes ◽  
Hydrodynamic Characteristics ◽  
Computational Domain ◽  
Acceptable Error ◽  
Marine Propellers ◽  
Fluent Software

In general, marine propellers have complicated geometries and as a consequence complicated flow around propeller. The aim of this work is to find an appropriate method and assess the turbulence model to approach the open water hydrodynamic characteristics of the marine propellers. In this work, a numerical modeling using a finite volume commercial code (FVM) for different turbulence models has been applied on the well known conventional screw propeller DTRC P4119. The 3-D solid model of P4119 is established using pro/E software and for the mesh generation ANSYS-ICEM has been used. Steady Reynolds-Averaged Navier Stokes (RANS) simulations are accomplished using FLUENT software with unstructured mesh in the rotating computational domain and structured mesh for the rest of the domain. The open water performance coefficients, thrust (KT), torque (KQ) and efficiency (η) have been calculated and compared with available experimental data to assess the applicability of different turbulence models for the open water study of propeller. This paper shows that, the accuracy of the CFD based on RANS equations is dependent on the used turbulence model and the RNG K-epsilon turbulence model yields to provide the most accurate results. Also, all the turbulence models via FLUENT software behave the same behavior for the total span of the advance coefficient (J) with two types of result accuracy. All the turbulence models shows high accuracy at low advance coefficient and this accuracy decreases but with an acceptable error till it decreases suddenly at the maximum advance coefficient.

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