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Delegates are invited to meet and discuss with the poster presenters in this topic directly after the session 'Wind turbine noise: How to avoid disturbing the neighbours' taking place on Tuesday, 11 March 2014 at 16:30-18:00. The meet-the-authors will take place in the poster area.

YOSHITAKA TOTSUKA Wind Energy Institute of Tokyo Inc., Japan
Co-authors:
YOSHITAKA TOTSUKA (1) F P HIROSHI IMAMURA (1) NEMANJA KOMATINOVIC (1) YUKO UEDA (1) AKIHIRO SUZUKI (1) CHISACHI KATO (2) AKIYOSHI IIDA (3) YASUMASA SUZUKI (4)
(1) Wind Energy Institute of Tokyo Inc., TOKYO , Japan (2) University of Tokyo, TOKYO, Japan (3) Toyohashi Univ. Tech. , Toyohashi, Japan (4) Nihon University, TOKYO, Japan

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Presenter's biography

Biographies are supplied directly by presenters at EWEA 2014 and are published here unedited

Mr. Totsuka has been working in the wind industry for around 4 years. He is currently an analysis group leader at the Wind Energy Institute of Tokyo Inc. He
studied numerical simulation of turbulent flow at the Keio University as Ph.D candidate in Yokohama. Before he finish his studies he moved to DELL corporation and
spent 6 years as senior analyst. and currently he has been involved in the design code development of floating offshore wind turbine project
and the wind turbine noise reduction project. His research focus on the Aero-servo-elastic analysis, noise analysis and design optimization.

Abstract

Development of turbulent inflow noise model for wind turbine blades

Introduction

Renewable energy gathers attention more than ever in Japan due to the accident of nuclear power stations in Fukushima caused by the Great East Japan Earthquake. Especially wind energy comes into prominence in terms of economical advantage. However, toward widespread use of wind energy in Japan, sufficient comprehension of wind turbine noise is required to mitigate wind turbine noise effectively. Because noise from rotor blade is predominant among wind turbine noise, authors have developed more accurate aero-acoustic noise prediction model for wind turbine blade under support of Japanese Ministry of Environment.

Approach

Our main purpose is to develop and construct accurate aero-acoustic noise prediction model for wind turbine blade. For rigorous and accurate wind turbine blade noise model effectively, we modified and improved existing NREL's semi-empirical aero-acoustic noise prediction code incorporated into aero-elastic simulation code, FAST. Construction and verification of wind turbine blade noise model is conducted with wind tunnel test results of various airfoil types and field test results of multi-mega watt wind turbine.

Main body of abstract

NREL's semi-empirical aero-acoustic blade noise prediction model, hereinafter abbreviated as FAST noise model, is well organized and consists of following noise sources.
1). Turbulent boundary layer trailing edge
2). Separated flow
3). Laminar boundary layer vortex shedding
4). Trailing-edge bluntness vortex shedding
5). Tip vortex
6). Turbulent inflow
However we found turbulent inflow noise model caused serious gap on the accuracy of FAST noise model through comparison with various field test results. Then we focused on improvement of turbulent inflow noise model among six aero-acoustic blade noise.
Firstly we assumed various vortex scales of flow around airfoil should influence broadband turbulent inflow noise as the result of interaction between turbulent inflow and airfoil. Then we carried out wind tunnel tests for various turbulent characteristics to figure out how turbulent length scale and turbulence intensity affect broadband noise by turbulent inflow.
From what we learned during wind tunnel tests, we confirmed and concluded new scale parameter and concept are required for turbulent inflow noise model. Then we developed and constructed an improved turbulent inflow noise model based on the wind tunnel test results. Obtained our model results showed quite good agreement with field test results of multi-mega watt wind turbine blade. Comparison of simulated result and measured result in field test is also investigated in terms of amplitude modulation noise.

Conclusion

In this study, we developed and constructed improved turbulent inflow noise model through comparison with wind tunnel experiments under various turbulence characteristics. Also assessment and verification of our improved aero-acoustic noise prediction model was performed on field test results of multi-mega watt wind turbine. Obtained our model results showed quite good agreement with field test results. Comparison of simulated result and measured result in field test is also investigated in terms of amplitude modulation noise. Further construction of blade noise model is continued with another field test for serrated blade.


Learning objectives
After attending this session, delegates will be able to:
1). Recognize the current challenge of wind turbine blade noise prediction
2). Explain the latest advances of the blade noise prediction model
3). Learn about concepts of turbulent inflow noise model