idsession
code

12

A-3-1

Advanced Reseach Report for Small
Horizontal Axis Wind Turbine with
Prof. Dr. Yukimaru Shimizu
Double Pitch Control mechanism

Nagoya Sangyo University

58

A-3-2

Performance Prediction ofHorizontal Axis Wind Turbine using
CFD

Prof. Masami Suzuki

University of the Ryukyus

73

A-3-3

Load Analysis of the Two-Bladed
Horizontal Axis Wind Turbine byHILS

Dr. Shigemitsu Aoki

National Institute of Advanced
Industrial Science and Technology

93

A-3-4

Numerical Analysis of a small HAWT Dr. Noriki Iwanaga

Research Center of Computational
Mechanics,Inc.

49

A-3-5

A study evaluating a wind condition
model for the generator output
Mr. Ryo Kobayashi
variation of a grid-connected small
wind turbine

The University of Tokyotitle

Presenter nameAffiliation

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1-Nov. 10:45 - 12:15 [ Small wind and hybrid system (1) ]Advanced Reseach Report for Small Horizontal Axis Wind Turbine with
Double Pitch Control mechanism
Yukimaru Shimizu1, Kiyoshi Okamura1, Ketu Ri2 and Den Tei2
1Nagoya Sangyo University, 2Nagoya Sangyo Univ. Graduate student,

Abstract:
The paper describes the outline of advanced development of small horizontal axis wind turbine with double pitch control
mechanism.
Multi-poles permanent magnets are used in the generator.
Two kinds of driving methods are compared in this paper. One of them is the direct connection as the generator is directly
connected to the wind turbine rotor. Another one is two stage axes connection.
The generator is connected to the turbine rotor by two stage axes namely, gear box. The experimental data of directconnection turbine is compared with that of two stage axes one.
Small HAWT of direct type generates the electric power from 2.0m/s~2.5m/s low wind speed. Also, the power coefficient,
Cp is a little improved, and is compared with one of two axes type HAWT.
The characteristics of the direct drive type are explained as the following.
1) The improved wind turbine has no gear box, namely, the turbine rotor is directly connected to the generator.
2) The diameter of turbine rotor is enlarged from about 3m to 3.6m.The diameter becomes large to 0.6m. As the result, thestarting wind speed, namely, cut-in wind speed is improved to 2m/s~2.5m/s.
3) The large thickness aerofoil section is applied to the blade root area.
4) The improved multi-poles generator has many permanent magnets with strong magnetic force on rotor surface and many
thick coils are set on the static surface side (no rotor side) of generator. As the result, a little large current can be generated inthe coils.
5) The rotation speed of wind turbine is passively controled by new double pitch control mechanism to variable wind speed,and excessive rotation speed more than 350rpm can be saved.
6) It is difficult to construct a wind turbine pole on the weak soil.
One know-how is proposed to construct a wind turbine pole on the weak soil. It is explained such as the following. The weaksoil are diged on 2m depth and 2m suare. Many sand bags (soil bag:no problem) are placed in two stages on the bottom. Thesteel frame is constructed by the welding. A wind turbine pole is standed up on the base.
In the paper, many data and results are explained.

Performance Prediction of Horizontal Axis Wind Turbine using CFD
Masami Suzuki
University of the Ryukyus

Abstract:
It is difficult to predict only by a wind tunnel experiment, because there are the problems such as the scale effect with respect
to the actual wind turbine performance. Therefore, the practical use of CFD that the enough validation was made byexperiments becomes more and more important in future.
In this paper, it is attempted to solve the more accurate characteristics of a wind turbine for a short time, using the coarse
grid. The CFD code is an in-house incompressible finite volume Navier-Stokes solver which is developed by the author. Thesolver is based on structured grids and the use of curve-linear boundary fitted coordinates. The SIMPLE algorithm is used forpressure-velocity coupling. The convection term is calculated using the QUICK scheme and the other terms in space arecalculated using the 2nd order difference schemes. The proven and computationally efficient Launder-Sharma low-Reynoldsnumber k- turbulence model is used in this report.
In this study, in order to validate an analysis precision of CFD, the results of two-bladed and three-bladed wind turbines arecompared with ones of experiments. The accuracy of the performance prediction was investigated. The possibility that theerrors overlooked by the experiments and the unprecedented phenomenon are found has been shown. In addition, for twobladed and three-bladed wind turbines both, the predictions of the thrust coefficients and the power coefficients are inagreement with ones of experiment. The center of thrust becomes approximately constant position for both two-bladed andthree bladed turbines in the high tip speed ratio. The effectiveness of the performance prediction by CFD has been shown.
However the predicted thrust and power coefficients of the three-bladed turbine shift upward the experimental results. Although
it is necessary to do the detailed examination, if the experimental data correct, it is presumed that a peculiar feature exist in thehorizontal axis wind turbine. The efficiency is proposed to evaluate the wind turbine performance comparing with the otherturbomachinery in this paper. The efficiency defined in this paper is in good agreement between the CFD and the experiment
for the operation range over the higher tip speed ratio than not stall one. In this regard, it is suggested for the tree-bladed turbinethat the difference results between the CFD and the experiment may be caused by a problem except CFD. It may be suggested
to perform the detailed error examination which is included in the experimental device and the measurement procedure. In
addition, the maximum efficiencies are 50% and 60% for the two-bladed and the three-bladed turbine, respectively. The
efficiency of two-bladed turbine which has the simple blade form becomes lower than that of the three-bladed turbine.

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1-Nov. 10:45 - 12:15 [ Small wind and hybrid system (1) ]Load Analysis of the Two-Bladed Horizontal Axis Wind Turbine by HILS
Shigemitsu Aoki and Tetsuya Kogaki
National Institute of Advanced Industrial Science and Technology

Abstract:
1. Overview
In order to make an approach according to the Load Analysis of the three-bladed small sized horizontal axis wind turbine, the basic
equations were derived by Lagrange’s method on Eulerian coordinate system.
An aero-elastic simulation model named AIST-RAM (AIST Real-Time Model), that calculates characteristics of the motion and the load
was developed referring to the basic equations and another factors such as an aerodynamic force acting on the blades that is strongly affectedby the motion and elasticity of the blades itself. Furthermore, the model was evaluated through experimental operations of a small sized threebladed horizontal-axis wind turbine which was constructed as well as the specified management system called Hard- wear in the Loop (HIL).
Through the successive evaluation by field testing accompanied with real-time simulation arranged by the Hard-wear in the Loop System,
the credibility of the simulation soft-wear is gradually confirmed.

2. Background
In order to improve the technology of design and evaluation as well as the cost-reduction as to development of the small wind-turbine, theapplication of recent IT technology is under discussion now.Although technology of real-time simulation together with an evaluation systemcalled Hard-wear In the Loop (HILS) is well established among the industry like automobile or aerospace, there is no successful caseaccording to the wind-turbine industry.

3. Modeling
In order to introduce the basic equations that ordinate the inertial force acting on the system, ”Eulerian coordinate system” was adopted asa generalized coordinates. Basic attitude of the rotor-blade was conducted with four degree of freedom defined as β , ψ , θ and φ , as is shownin Figure 1.(See. Proc. Paper) First International Symposium on Flutter and its Application, 2016 Hence β is defined as the pitch angle that
adjust the attack angle around the axis approximately put on the aerodynamic center of each blade section, ψ is defined as the azimuth angleof the blade rotating on the main axis of the rotor, θ is defined as the tilt angle that starts from perpendicular position and φ is defined as yaw
angle of the main axis according to the directional change.

4. Simulation model construction
A circumstances of time-driven simulation system was prepared to establish the construction of the model shown in Figure 2. (See. Proc.
Paper)

5. Load analyses of the three bladed small Horizontal Axis Wind Turbine
Co-responding to IEC/JIS standards, the result of load-measurement in field testing was arranged to realize the fair comparison under thecondition of each load case of the standards.

6. Summary
An aero-elastic simulation model named AIST-RAM (AIST Real-Time Model), that represents characteristics of the motion was developed
referring to the basic equations and another factors such as an aerodynamic force acting on the blades that is strongly affected by the motionand elasticity of the blades itself.
Through the successive evaluation by field testing accompanied with real-time simulation arranged by the Hard-wear in the Loop System,
the simulation model shows significant credibility and preciseness particularly for the inertial property.

Numerical Analysis of a small HAWTNoriki Iwanaga1, Shunsuke Negishi1, Takashi Hashiba1, Katsuhito Akashi2,Hideki Kitajima1, Hiroshi Ishikawa1 and Kenichiro Yoshimi1
1Research Center of Computational Mechanics,Inc., 2hiyo Aircraft Manufacturing Co., Ltd.,

Abstract:
A small HAWT is numerically studied on its dynamical, structural, and acoustical features. The 3D structural analysis done
by a commercial code after multibody dynamics calculation done by the FAST provides us the stress-strain distribution on theblade surface, which is helpful for the damage prediction. The acoustic analysis done by the FLUENT and our in-house codegives us not only frequency character but also time historical one at any observation points. As a result, impulsive sound isobserved at observation points near the turbine.

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1-Nov. 10:45 - 12:15 [ Small wind and hybrid system (1) ]A study evaluating a wind condition model for the generator output
variation of a grid-connected small wind turbine
Ryo Kobayashi1, Takeshi Kamio1, Mitsumasa Iino2, Makoto Iida1 and Chuichi Arakawa1
1The University of Tokyo, 2Ashikaga Institute of Technology,

Abstract:
Equipment certification is required for the installation of grid-connected small wind turbines in Japan. At present, thecertification procedure is only available for a pair of small wind turbines and a PCS (Power Conditioning System). However,such a procedure is inefficient in terms of both cost and time. Therefore, this paper proposes a procedure for the independentcertification of a PCS. It is apparent that the procedure would require the development of an output model for a small windturbine generator. in the previous study, we confirmed that the experimental results for averaged generator output in one and ten
minute matched the field results. However, some problems were faced during the evaluation of the output characteristics, suchas a sudden change in the output. One of these problems was related to the wind condition model. We investigated therelationship between wind conditions and generator output during sudden changes using field data In this study, we investigated
the sudden change in the generator output due to various wind conditions.
Small wind turbine simulations were executed using FAST(Fatigue Aerodynamics Structures, and Turbulence), which wasdeveloped by the NREL (National Renewable Energy Laboratory). FAST calculates wind power based on BEM (BladeElement and Momentum theory) and analyzes all mechanical components of a turbine, such as the tower, nacelle, and blades.
In this study, an investigation of a commercially available small wind turbine (NWG-1K, Nikko Company) that is suitablefor grid connections was conducted.
In this study, a comparison was made between the simulation results and field data. The generator output of the NWG-1K
turbine was simulated using NTM (Normal Turbulence Model), and the maximum value of the power change at 0.1- second
intervals was calculated from the simulation results. The NTM is defined in the IEC (International Electro technicalCommission) 61400-2, which details the design requirements for small wind turbines, and it is the turbulence model thatconsiders the effects of varying wind speed, varying direction, and rotation sampling.
The field data and simulation results were compared in this study, and the following was concluded:•The simulation results using the NTM were less than the field data.
•A modified NTM may be necessary to simulate the sudden changes in the generator output at 0.1- second intervals andto consider the effects of turbulence intensity.

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