scholarly journals Study of a Bi-Vertical Axis Turbines Farm Using the Actuator Cylinder Method

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5199
Author(s):  
Laurie Jégo ◽  
Sylvain S. Guillou
Keyword(s):  
Kinetic Energy ◽  
Computing Time ◽  
Vertical Axis ◽  
Power Production ◽  
Time Cost ◽  
Ansys Fluent ◽  
Tidal Turbines ◽  
Flow Changes ◽  
Cylinder Method ◽  
Reasonable Computing

Vertical axis turbines, which extract kinetic energy from currents, can produce electricity independently from a current’s direction. Hence, this type of turbines raises interest for harvesting energy from tidal currents, where flow changes direction during flood and ebb tides, and where currents present large variation of direction during tide. Methods for representing vertical axis turbines in tidal farms should be implemented in order to predict correctly power production with an acceptable time cost. The Actuator Cylinder (AC) is one of them. Numerical results in terms of wakes, with the study of velocity profiles, and efforts are compared to experiences, as well as showed that the method is sufficiently accurate and for a reasonable computing time, which is of prime importance for tidal turbines farms studies. The Actuator Cylinder method is implemented in ANSYS Fluent in a 2D stationary resolution. The method is then applied to a double levels of two counter-rotating rotors marine turbine designed by Hydroquest. Wake and power production of a single turbine and several farm configurations are studied under different current conditions (magnitude and direction).

scholarly journals Effect of Pitch Parameters on Aerodynamic Forces of a Straight-Bladed Vertical Axis Wind Turbine with Inclined Pitch Axes

2021 ◽  
Vol 11 (3) ◽  
pp. 1033
Author(s):  
Jia Guo ◽  
Timing Qu ◽  
Liping Lei
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Speed Ratio ◽  
Incline Angle ◽  
Asymmetric Distribution ◽  
Vertical Axis Wind Turbine ◽  
Power Performance ◽  
Aerodynamic Forces ◽  
Ansys Fluent ◽  
Pitch Regulation

Pitch regulation plays a significant role in improving power performance and achieving output control in wind turbines. The present study focuses on a novel, pitch-regulated vertical axis wind turbine (VAWT) with inclined pitch axes. The effect of two pitch parameters (the fold angle and the incline angle) on the instantaneous aerodynamic forces and overall performance of a straight-bladed VAWT under a tip-speed ratio of 4 is investigated using an actuator line model, achieved in ANSYS Fluent software and validated by previous experimental results. The results demonstrate that the fold angle has an apparent influence on the angles of attack and forces of the blades, as well as the power output of the wind turbine. It is helpful to further study the dynamic pitch regulation and adaptable passive pitch regulation of VAWTs. Incline angles away from 90° lead to the asymmetric distribution of aerodynamic forces along the blade span, which results in an expected reduction of loads on the main shaft and the tower of VAWTs.

Study the Effect of Air Pulsation on the Flame Characteristics

2021 ◽  
Author(s):  
Mahmoud Magdy ◽  
M. M. Kamal ◽  
Ashraf M. Hamed ◽  
Ahmed Eldein Hussin ◽  
Walid Aboelsoud Torky
Keyword(s):  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Combustion Products ◽  
Combustion Efficiency ◽  
Industrial Applications ◽  
Detached Eddy Simulation ◽  
Ansys Fluent ◽  
Pulsating Flames ◽  
Flow Variables ◽  
Air Pulsation

Pulsating combustion is used in a lot of industrial applications like conveyer drying, spray, boilers of commercial scale because its great role in increasing combustion efficiency and producing environmentally friendly combustion products. This paper evaluates how different frequencies (100, 200, 300, 400 and 500) rad/s applied to air velocity view a lot of improvements in the combustion and flow variables (v, T, NO and turbulent kinetic energy) and the effect of adding cross excess air to air pulsation with 500 rad/s frequency on the same flow variables. The performance of pulsating flames was numerically modulated by using Ansys Fluent 16 commercial package by building a 2D combustion chamber of Harwell standard furnace boundary condition on Ansys geometry and divided it into 61000 elements in Ansys meshing 16. Eddy Dissipation Model (EDM) is used to solve transient numerical combustion equations and Detached Eddy Simulation (DES) as viscous model. Converged numerical results have shown that increasing frequency from 100 to 500 rad/s increase average velocities of combustion products and turbulent kinetic energy by 22% and 80 respectively. The pollutant NO decrease by 60% and the time average temperature decrease from 1900 k to 1000 k.

Coupled Dynamics of a Vertical Axis Wind Turbine (VAWT) With Active Blade Pitch Control on a Semi-Submersible Floater

2018 ◽  
Author(s):  
Ebert Vlasveld ◽  
Fons Huijs ◽  
Feike Savenije ◽  
Benoît Paillard
Keyword(s):  
Wind Turbine ◽  
Wind Velocity ◽  
Vertical Axis ◽  
Power Production ◽  
Mooring Line ◽  
Vertical Axis Wind Turbine ◽  
Coupled Dynamics ◽  
Low Frequencies ◽  
Pitch Control ◽  
Thrust And Torque

A vertical axis wind turbine (VAWT) typically has a low position of the center of gravity and a large allowable tilt angle, which could allow for a relatively small floating support structure. Normally however, the drawback of large loads on the VAWT rotor during parked survival conditions limits the extent to which the floater size can be reduced. If active blade pitch control is applied to the VAWT, this drawback can be mitigated and the benefits can be fully utilized. The coupled dynamics of a 6 MW VAWT with active blade pitch control supported by a GustoMSC Tri-Floater semi-submersible floater have been simulated using coupled aero-hydro-servo-elastic software. The applied blade pitch control during power production results in a steady-state thrust curve which is more comparable to a HAWT, with the maximum thrust occurring at rated wind velocity. During power production, floater motions occur predominantly at low frequencies. These low frequency motions are caused by variations in the wind velocity and consequently the rotor thrust and torque. For the parked survival condition, it is illustrated that active blade pitch control can be used to effectively reduce dynamic load variations on the rotor and minimize floater motions and mooring line tensions.

Performance Modeling of Ducted Vertical Axis Turbine Using Computational Fluid Dynamics

2013 ◽  
Vol 47 (4) ◽  
pp. 36-44 ◽  
Author(s):  
Prasun Chatterjee ◽  
Raymond N. Laoulache
Keyword(s):  
Performance Modeling ◽  
Flow Direction ◽  
Computational Cost ◽  
Vertical Axis ◽  
Area Ratio ◽  
Diameter Ratio ◽  
Turbulent Model ◽  
Ansys Fluent ◽  
Second Order In Time ◽  
Vertical Axis Turbine

AbstractVertical axis turbines (VATs) excel over horizontal axis turbines in their independent flow direction. VATs that operate in an enclosure, e.g., a diffuser shroud, are reported to generate more power than unducted VATs. A diffuser-shrouded, high solidity of 36.67%, three-blade VAT with NACA 633-018 airfoil section is modeled in 2-D using the commercial software ANSYS-FLUENT®. Incompressible, unsteady, segregated, implicit, and second order in time and space solver is implemented in association with the Spalart-Allmaras turbulent model with a reasonable computational cost. The computational results are assessed against experimental data for unducted VAT at low tip speed ratios between 1 and 2 for further numerical analysis on diffuser models. Different diffuser designs are investigated using suitable nozzle size, area ratio, length-to-diameter ratio and angles between the diffuser inner surfaces. The numerical model shows that, for a specific diffuser design, the ducted VAT performance coefficient can be augmented by almost 90% over its unducted counterpart.

scholarly journals NUMERICAL SIMULATION OF AIRFLOW AROUND VEHICLE MODELS

2018 ◽  
Vol 56 (3) ◽  
pp. 370
Author(s):  
Nguyen Van Thang ◽  
Ha Tien Vinh ◽  
Bui Dinh Tri ◽  
Nguyen Duy Trong
Keyword(s):  
Numerical Simulation ◽  
Kinetic Energy ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Forces ◽  
Dissipation Energy ◽  
Ansys Fluent ◽  
Car Model ◽  
Airflow Field ◽  
Fluent Software

This article carries out the numerical simulation of airflow over three dimensional car models using ANSYS Fluent software. The calculations have been performed by using realizable k-e turbulence model. The external airflow field of the simplified BMV M6 model with or without a wing is simulated. Several aerodynamic characteristics such as pressure distribution, velocity contours, velocity vectors, streamlines, turbulence kinetic energy and turbulence dissipation energy are analyzed in this study. The aerodynamic forces acting on the car model is calculated and compared with other authors.

Assessment of the numerical and experimental performance of screw tidal turbines

2018 ◽  
Vol 232 (7) ◽  
pp. 912-925 ◽  
Author(s):  
Hamid Rahmani ◽  
Mojtaba Biglari ◽  
Mohammad Sadegh Valipour ◽  
Kamran Lari
Keyword(s):  
Output Power ◽  
Water Flow ◽  
Cross Sections ◽  
Turbine Blades ◽  
Transient State ◽  
Experimental Results ◽  
Ansys Fluent ◽  
Tidal Turbines ◽  
Collision Problem ◽  
Mesh Independence

This study was aimed at the numerical and experimental modeling of water flow during collision between water and vertical screw turbine blades with different cross sections (i.e. Darrieus, spoon, and airfoil). ANSYS Fluent was used to model water flow under tidal currents in a flume, and mesh independence was ensured after the selection of appropriate geometry. The collision problem was then solved in the transient state, and results on the momentum and power generated by different inlet velocities and different blade cross sections were analyzed. The findings showed that torque and turbine power increased with increasing inlet velocity. Subsequently, a turbine was experimentally created, with cross sections drawn in the numerical model and tested under the same conditions as that imposed on the model. Installing a multimeter on the turbine enabled the generation of turbine power in different dimensions. The resultant power increased with rising turbine dimensions. After obtaining the numerical and experimental results, the value of the output power of the turbine was validated. The validation indicated a 7% difference in output power between the numerical and experimental results, indicating acceptable accuracy.

scholarly journals Improving the efficiency of carousel wind turbine using aerodynamic shield

2021 ◽  
Vol 2119 (1) ◽  
pp. 012093
Author(s):  
A F Serov ◽  
V N Mamonov ◽  
A D Nazarov ◽  
N B Miskiv
Keyword(s):  
Kinetic Energy ◽  
Flow Velocity ◽  
Air Flow ◽  
Cylindrical Body ◽  
Vertical Axis ◽  
Rotor Blades ◽  
Heat Generator ◽  
Axis Of Rotation ◽  
Wheel Torque ◽  
Air Flow Velocity

Abstract The problem of increasing the efficiency of using the oncoming air flow for a wind wheel with a vertical axis of rotation, which is a mechanical drive of the wind heat generator, is considered. It is proposed to increase the efficiency of the device by installing an aerodynamic shield for the air flow oncoming the wind wheel. Such a shield is a cylindrical body in which a heat generator is placed. The shield creates an effect of confuser, leading to an increase in the speed and, consequently, in the kinetic energy of the air flow acting on the rotor blades. It is shown experimentally that the presence of an aerodynamic shield under the conditions of the experiments carried out at an incoming air flow velocity of ~ 1 m/s leads to a practical doubling of the wind wheel torque.

scholarly journals Aerodynamics and Modal Analysis for the Combined Vane type Vertical Axis Wind Turbine

2018 ◽  
Vol 7 (4.38) ◽  
pp. 1395 ◽  
Author(s):  
Kadhim H. Suffer ◽  
Yassr Y. Kahtan ◽  
Zuradzman M. Razlan
Keyword(s):  
Wind Turbine ◽  
Modal Analysis ◽  
Natural Frequencies ◽  
Turbine Blades ◽  
Vertical Axis ◽  
Turbine Rotor ◽  
Mode Shapes ◽  
Vertical Axis Wind Turbine ◽  
Ansys Fluent ◽  
Starting Torque

The present global energy economy suggests the use of renewable sources such as solar, wind, and biomass to produce the required power. The vertical axis wind turbine is one of wind power applications. Usually, when the vertical axis wind turbine blades are designed from the airfoil, the starting torque problem begins. The main objective of this research is to numerically simulate the combination of movable vanes of a flat plate with the airfoil in a single blade configuration to solve the starting torque problem. CFD analysis in ANSYS-FLUENT and structural analysis in ANSYS of combined blade vertical axis wind turbine rotor has been undertaken. The first simulation is carried out to investigations the aerodynamic characteristic of the turbine by using the finite volume method. While the second simulation is carried out with finite element method for the modal analysis to find the natural frequencies and the mode shape in order to avoid extreme vibration and turbine failure, the natural frequencies, and their corresponding mode shapes are studied and the results were presented with damping and without damping for four selected cases. The predicted results show that the static pressure drop across the blade increase in the active blade side because of the vanes are fully closed and decrease in the negative side because of the all the vanes are fully open. The combined blade helps to increase turbine rotation and so, thus, the power of the turbine increases. While the modal results show that until the 5th natural frequency the effect of damping can be neglected. The predicted results show agreement with those reported in the literature for VAWT with different blade designs.   

Numerical Simulation of Convective-Radiative Heat Transfer in a Solar Chimney

2014 ◽  
Author(s):  
Bernardo Buonomo ◽  
Oronzio Manca ◽  
Sergio Nardini ◽  
Gianluca Tartaglione
Keyword(s):  
Kinetic Energy ◽  
Electrical Power ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Three Dimensional Model ◽  
Solar Chimney ◽  
Ansys Fluent ◽  
Heating And Cooling ◽  
Air Stream

Solar chimney is a new method to produce electrical power. It employs solar radiation to raise the temperature of the air and the buoyancy of warm air to accelerate the air stream flowing through the system. By converting thermal energy into the kinetic energy of air movement, solar chimneys have a number of different applications such as ventilation, passive solar heating and cooling of buildings, solar-energy drying, and power generation. Moreover, it can be employed as an energy conversion system from solar to mechanical. A component, such as a turbine or piezoelectric component, set in the path of the air current, converts the kinetic energy of the flowing air into electricity. In this paper, a numerical investigation on a prototypal solar chimney system integrated in a south facade of a building is presented. The chimney is 4.0 m high, 1.5 m wide whereas the thickness is 0.20 m for the vertical parallel walls configuration and at the inlet 0.34 m and at the outlet 0.20 m for convergent configuration. The chimney consists of a converging channel with one vertical wall and one inclined of 2°. The analysis is carried out on a three-dimensional model in airflow and the governing equations are given in terms of k-ε turbulence model. The problem is solved by means of the commercial code Ansys-Fluent. The numerical analysis was intended to examine the effect of the solar chimney’s height and spacing. Further, comparison between radiative and non-radiative model is examined and discussed. Results are given in terms of wall temperature distributions, air velocity and temperature fields and transversal profiles for a uniform wall heat flux on the vertical wall equal to 300 W/m2. Thermal and fluid dynamics behaviors are evaluated in order to have some indications to improve the energy efficiency of the system.

scholarly journals Wake of a Ducted Vertical Axis Tidal Turbine in Turbulent Flows, LBM Actuator-Line Approach

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4273 ◽  
Author(s):  
Mikaël Grondeau ◽  
Sylvain Guillou ◽  
Philippe Mercier ◽  
Emmanuel Poizot
Keyword(s):  
Turbulent Flows ◽  
Vertical Axis ◽  
Tidal Currents ◽  
Eddy Simulation ◽  
Tidal Turbines ◽  
Tidal Turbine ◽  
Vertical Axis Tidal Turbine ◽  
Ambient Turbulence ◽  
The Cost ◽  
Boltzmann Method

Vertical axis tidal turbines are devices that extract the kinetic energy from tidal currents. Tidal currents can be highly turbulent. Since ambient turbulence affects the turbine hydrodynamic, it is critical to understand its influence in order to optimize tidal farms. Actuator Line Model (ALM) combined with Large Eddy Simulation (LES) is a promising way to comprehend this phenomenon. In this article, an ALM was implemented into a Lattice Boltzmann Method (LBM) LES solver. This implementation gives good results for predicting the wake of a vertical axis tidal turbine placed into a turbulent boundary layer. The validated numerical configuration was then used to compute the wake of a real size ducted vertical axis tidal turbine. Several upstream turbulence rates were simulated. It was found that the shape of the wake is strongly influenced by the ambient turbulence. The cost-to-precision ratio of ALM-LBM-LES compared to fully resolved LBM-LES makes it a promising way of modeling tidal farms.

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