Effects of Disturbance of Current Field on Power Characteristics of a Floating Type Pitch-Controlled VAMT in a Real Sea

2016 ◽  
Author(s):  
Tomoki Ikoma ◽  
Koichi Masuda ◽  
Hiroaki Eto ◽  
Chang-Kyu Rheem ◽  
Osamu Enomoto
Keyword(s):  
Fluid Velocity ◽  
Vertical Axis ◽  
Ocean Waves ◽  
Floating Body ◽  
Maximum Output ◽  
Power Characteristics ◽  
Turbine Performance ◽  
Velocity Changes ◽  
Floating Type ◽  
Japanese Islands

While a type of marine turbine for tidal current generation can be chosen from several types, a vertical axis marine turbine (VAMT) should be better in Japan because sea areas around Japanese islands where current velocity is sufficient are limited. This study conducted a sea test of a VAMT of a floating type installed with six straight pitch-controllable blades. The cycloidal mechanism was adapted for the pitch control. The purpose of the study is to understand effects of ocean waves and motion of a floating body on turbine performance and behaviours of the VAMT in unideal current conditions. Besides, the data taken should be effective to consider that effects in order to design VAMTs. The setup with the setting angle of −30 degrees suggested highest performance from the sea tests, then 15% in maximum turbine power and maximum output was 40W. Ocean waves strongly affected on the turbine performance because fluid velocity changes due to ocean waves and it was unable to neglect the variation of the velocity in spite of small. The characteristics of the turbine sensitively varied because of ocean waves. The results suggested that during accelerating and decelerating incoming fluid speed, characteristics of the turbine were different in each case.

scholarly journals Analisa pengaruh sudut sudu terhadap kinerja turbin kinetik poros horisontal dan vertikal

2018 ◽  
Vol 1 (1) ◽  
pp. 51
Author(s):  
Yasinta Sindy Pramesti
Keyword(s):  
Flow Rate ◽  
Flow Direction ◽  
Mechanical Energy ◽  
Fluid Velocity ◽  
Maximum Output Power ◽  
Rate Variation ◽  
Maximum Output ◽  
Direction Angle ◽  
Turbine Performance ◽  
Higher Power

Kinetic turbine is a type of power plant that utilizes the energy stored in the water flow ie potential energy and kinetic energy that will be converted into mechanical energy. One of the factors that affect turbine performance is angle angle. The research methodology in this kinetic turbine utilizes the fluid velocity (water) that moves with. The variation of the flow steering angle with the angle to be studied uses an angle of 5 ° 10 °, 15 ° and flow rate variation 50, 70 and 90 m³ / hr. In addition, this kinetic turbine uses vertical and horizontal axis variations. Based on the result of the research, it can be concluded that the maximum output power produced by turbine at 1.53 Watt occurred at 90 m3 / hr discharge with flowing direction angle of 15⁰. The highest efficiency of 18% occurs at a flow rate of 50 m3 / h with a flow direction angle of 15⁰. Horizontal axle turbines have slightly higher power and efficiency values when compared to a vertical axle turbine.

Analysis of the First Order and Slowly Varying Motions of an Axisymmetric Floating Body in Bichromatic Waves

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
João Pessoa ◽  
Nuno Fonseca ◽  
C. Guedes Soares
Keyword(s):  
Vertical Cylinder ◽  
Vertical Axis ◽  
Second Order ◽  
The Body ◽  
Floating Body ◽  
Drift Motion ◽  
First Order ◽  
Motion Responses ◽  
Simple Geometry ◽  
Good Agreement

The paper presents an experimental and numerical investigation on the motions of a floating body of simple geometry subjected to harmonic and biharmonic waves. The experiments were carried out in three different water depths representing shallow and deep water. The body is axisymmetric about the vertical axis, like a vertical cylinder with a rounded bottom, and it is kept in place with a soft mooring system. The experimental results include the first order motion responses, the steady drift motion offset in regular waves and the slowly varying motions due to second order interaction in biharmonic waves. The hydrodynamic problem is solved numerically with a second order boundary element method. The results show a good agreement of the numerical calculations with the experiments.

A Second Order Lagrangian Model for Irregular Ocean Waves

2005 ◽  
Vol 128 (3) ◽  
pp. 177-183 ◽  
Author(s):  
Sébastien Fouques ◽  
Harald E. Krogstad ◽  
Dag Myrhaug
Keyword(s):  
Specular Reflection ◽  
Fluid Velocity ◽  
Equations Of Motion ◽  
Wave Theory ◽  
Ocean Waves ◽  
Second Order ◽  
Lagrangian Model ◽  
Lagrangian Description ◽  
Linear Wave ◽  
Irregular Solution

Synthetic aperture radar (SAR) imaging of ocean waves involves both the geometry and the kinematics of the sea surface. However, the traditional linear wave theory fails to describe steep waves, which are likely to bring about specular reflection of the radar beam, and it may overestimate the surface fluid velocity that causes the so-called velocity bunching effect. Recently, the interest for a Lagrangian description of ocean gravity waves has increased. Such an approach considers the motion of individual labeled fluid particles and the free surface elevation is derived from the surface particles positions. The first order regular solution to the Lagrangian equations of motion for an inviscid and incompressible fluid is the so-called Gerstner wave. It shows realistic features such as sharper crests and broader troughs as the wave steepness increases. This paper proposes a second order irregular solution to these equations. The general features of the first and second order waves are described, and some statistical properties of various surface parameters such as the orbital velocity, slope, and mean curvature are studied.

Drift Forces on a Floating Body of Simple Geometry Due to Second Order Interactions Between Pairs of Harmonics With Different Frequencies

2009 ◽  
Author(s):  
Joa˜o Pessoa ◽  
Nuno Fonseca ◽  
C. Guedes Soares
Keyword(s):  
Vertical Cylinder ◽  
Vertical Axis ◽  
Second Order ◽  
The Body ◽  
Floating Body ◽  
Order Problem ◽  
Simple Geometry ◽  
The Mean ◽  
Order Quantities ◽  
Drift Forces

The paper presents an investigation of the slowly varying second order drift forces on a floating body of simple geometry. The body is axis-symmetric about the vertical axis, like a vertical cylinder with a rounded bottom and a ratio of diameter to draft of 3.25. The hydrodynamic problem is solved with a second order boundary element method. The second order problem is due to interactions between pairs of incident harmonic waves with different frequencies, therefore the calculations are carried out for several difference frequencies with the mean frequency covering the whole frequency range of interest. Results include the surge drift force and pitch drift moment. The results are presented in several stages in order to assess the influence of different phenomena contributing to the global second order responses. Firstly the body is restrained and secondly it is free to move at the wave frequency. The second order results include the contribution associated with quadratic products of first order quantities, the total second order force, and the contribution associated to the free surface forcing.

Study of a Wave Absorber in Various Distance Placed in a Sinusoidal Propagate Wave

2013 ◽  
Vol 302 ◽  
pp. 326-331 ◽  
Author(s):  
Zhen Zhong Yuan ◽  
Bhupendra Singh Chauhan ◽  
Hee Chang Lim
Keyword(s):  
Wind Wave ◽  
Wave Length ◽  
Ocean Waves ◽  
Floating Body ◽  
Environmental Condition ◽  
Wave Flume ◽  
Strong Source ◽  
Wave Heights ◽  
Ocean Environment ◽  
Fundamental Equations

Since there has been a rapid progress to understand the dynamics of an offshore floating body under an ocean environment, we undertake to generate the ocean waves in a lab-scale wind-wave flume. The study is aiming to observe and optimize the similar ocean environmental condition as input wave and to reduce the wall reflective wave. Several absorption methods are suggested to optimize the propagate wave by measuring the maximum and minimum of the standing wave envelope. There has been no optimized absorption method, as they highly depend on the wave period and the wave length. One of the methods - two fixed wave gauges measuring two wave heights and one wave phase - is applied in this study. In the present paper various approaches were used to analyze the results using the flume, by position of probes, with absorber and without absorber, different position, condition and angle of the wave absorber, This paper also focuses on the analysis of fundamental equations which describe the separating method of the incident and reflective wave, and finally we confirm that the wave absorber is highly efficient considering all the permutation and combination.From the study it is clear that there is a change in the wave amplitude at the receiving end then the generated end; wave absorber is a strong source to control the energy of the coming wave. With the changing the period of the wave, the reflectance is increasing when the period becomes larger.

Heuristic Coupling Design-Optimization between a Variable Speed Generator and a Wind Rotor

2017 ◽  
Vol 32 ◽  
pp. 133-138
Author(s):  
Cherif Khelifi ◽  
Fateh Ferroudji ◽  
Farouk Meguellati ◽  
Khaled Koussa
Keyword(s):  
Wind Turbine ◽  
Output Power ◽  
Wind Turbines ◽  
Electricity Market ◽  
Maximum Output Power ◽  
Vertical Axis ◽  
Mechanical Power ◽  
Maximum Output ◽  
Variable Speed ◽  
Electric Generator

A high emergence of wind energy into the electricity market needs a parallel efficient advance of wind power forecasting models. Determining optimal specific speed and drive-train ratio is crucial to describe, comprehend and optimize the coupling design between a wind turbine-rotor and an electric generator (EG) to capture maximum output power from the wind. The selection of the specific design speed to drive a generator is limited. It varies from (1-4) for vertical axis wind turbines and (6-8) for horizontal axis wind turbines. Typically, the solution is an iterative procedure, for selecting the adequate multiplier ratio giving the output power curve. The latter must be relatively appreciated to inlet and nominal rated wind speeds. However, instead of this tedious and costly method, in the present paper we are developing a novel heuristic coupling approach, which is economical, easy to describe and applicable for all types of variable speed wind turbines (VSWTs). The principle method is based on the fact that the mechanical power needed of the wind turbine (WT) to drive the EG must be permanently closer to the maximum mechanical power generated by the (WT).

Investigation of vertical axis wind turbine airfoil performance in rain

2017 ◽  
Vol 232 (2) ◽  
pp. 181-194 ◽  
Author(s):  
Zhenlong Wu ◽  
Yihua Cao
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Meteorological Condition ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Vertical Axis Wind Turbines ◽  
Turbine Performance ◽  
Practical Design ◽  
Wind Turbine Airfoil ◽  
Naca 0015

Rainfall is a common meteorological condition that wind turbines may encounter and by which their performance may be affected. This paper comprehensively investigates the effects of rainfall on a NACA 0015 airfoil which is commonly used in vertical axis wind turbines. A CFD-based Eulerian–Lagrangian multiphase approach is proposed to study the static, rotating, and oscillating performances of the NACA 0015 airfoil in rainy conditions. It is found that for the different airfoil movements, the airfoil performance can seriously be deteriorated in the rain condition. Rain also causes premature boundary layer separations and more severe flow recirculations than in the dry condition. These findings seem to be the first open reports on rain effects on wind turbine performance and should be of some significance to practical design.

Nondimensional Parameters’ Effects on Hybrid Darrieus–Savonius Wind Turbine Performance

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Armin Roshan ◽  
Amir Sagharichi ◽  
Mohammad Javad Maghrebi
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Power Output ◽  
Urban Areas ◽  
Model Performance ◽  
Vertical Axis ◽  
Favorable Effect ◽  
Turbine Performance ◽  
Primary Model ◽  
Overlap Ratio

Abstract Vertical axial wind turbines are the most commonly used turbines in residential and urban areas. This paper investigates the effect of combining Darrieus and Savonius wind turbines on power output and introduces a wind turbine with high starting torque addition to the wide working domain. A two-dimensional computational fluid dynamics transient simulation is developed, and a moving mesh is implemented for rotating moving parts. Comprehensive research has been carried out to investigate the effects of the initial overlap ratio (ɛ), arc angle Ø, and curvature (α) of Savonius blades on the performance of the turbine and 18 models are simulated at seven tip speed ratios. The results showed that combining the Darrieus turbine with the Savonius turbine has a favorable effect on self-starting performance. Also, it was observed that by changing each of the parameters, the primary model performance could be significantly improved. Finally, it is concluded that ɛ = 0.25, α = 0.25, and ∅ = 150 deg are the optimum values of the parameters which increase turbine power output compared to conventional vertical-axis turbines.

Sign in / Sign up

Export Citation Format

Share Document