Experimental study of particle dampers applied to wind turbine blades to reduce low-frequency sound emission
Time: 8:00 am
Author: Braj Bhushan Prasad
Abstract ID: 1125
Sound emission from an onshore wind turbine is one of the significant hurdles to use wind energy to its full potential. The vibration caused by the generator is transmitted to the blades, which radiates the sound to the surrounding. The purpose of this experimental study is to present a passive vibration reduction concept, which is based on the high damping properties of granular materials. The efficiency of this concept will be investigated using a laser scanning vibrometer device. For the experimental purpose in the laboratory, small-scale replicas inspired by the original configurations are used as reference geometries for the wind turbine generator and the blades. Vibrations of the prototype, with and without granular material filling, will be determined and compared with each other. The influence of the amount of granular material inside the structure is also investigated. Apart from this, different types of granular filling are examined with respect to their efficiency in reducing the amplitude of vibration of the structure while being as light as possible in order to design a lightweight solution, which increases the overall mass of the wind turbine marginally.
Amplitude modulations increase annoyance due to wind turbine noise immission
Time: 8:40 am
Author: Christoph Pörschmann
Abstract ID: 2589
Current literature suggests that annoyance of wind turbine noise is strongly affected by amplitude modulations (AM). A survey was carried out at five German residential study sites near wind turbines with a total of about 500 residents to study the effects of AM in more detail. Annoyance, disturbances, and the perception of wind turbine noise characteristics, including AM, were assessed. For each participant, address-related exposure to rating levels of wind turbines was estimated. Further, we carried out headphone-based listening experiments with participants from three of the five study areas and with non-exposed participants from another control location. In the listening experiments, perceived annoyance was rated for varying AM and for different A-weighted sound pressure levels for a total number of 79 subjects. As expected, the results show an increase in annoyance with sound pressure level. Furthermore, annoyance increased significantly with the extent of amplitude modulations. Interestingly, annoyance showed a strong rise as soon as amplitude modulations became audible in the signal and this rise was hardly affected by the sound pressure level. In our contribution, we present comparisons of the results of the survey and the listening experiments.
Attenuation of Torsional Vibration in the Drivetrain of a Wind Turbine using a Vibration Absorber
Time: 8:20 am
Author: Hyeongill Lee
Abstract ID: 2449
Attenuation of Torsional Vibration in the Drivetrain of a Wind Turbine using a Centrifugal Pendulum Absorber Byeongil Kim, Youkyung Han, and Hyeongill Lee The drivetrain of wind turbines consists of many complicated rotary elements such as planetary gear, parallel gear train, bearing etc. The drivetrain of the wind turbine are studied with many different modeling techniques in several works. However, the things come to complicated when considering a complete drivetrain of a wind turbine. In this study, the transfer matrix method will be utilized to analyze the torsional vibration of a sample wind turbine drivetrain. Each element in the drivetain of the sample wind turbine is modeled with a specific transfer matrix and the matrix for the whole drivetrain is derived by serial multiplications of individual matrices. Dynamic characteristics of the drivetrain are investigated with derived matrix. Then, the application of a centrifugal pendulum absorber(CPA) to the drivetrain to attenuate the torsional vibration in the system is studied. The transfer matrix for the CPA introduced in the previous study is used to determine the optimal configuration and location of the CPA. The CPA shows good performance on the torsion vibration reduction for the drivetrain of the sample wind turbine.