Experimental Vibration Analysis of a Small Scale Vertical Wind Energy System for Residential Use

Francesco Castellani,Francesco Natili,Alexander Hirschl,Mauro Peppoloni,Davide Astolfi,Daniele Buttà

doi:10.3390/machines7020035

Francesco Castellani, Francesco Natili + Show 4 more

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https://doi.org/10.3390/machines7020035

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Abstract

In the recent years, distributed energy production has been one of the main research topics about renewable energies. The decentralization of electric production from wind resources raises the issues of reducing the size of generators, from the MW scale of industrial wind farm turbines to the kW scale, and possibly employing them in urban areas, where the wind flow is complex and extremely turbulent because of the presence of buildings and obstacles. On these grounds, the use of small-scale vertical axis small wind turbines (VASWT) is a valid choice for on-site generation (OSG), considering their low sensitivity with respect to turbulent flow and that there is no need to align the turbine with wind direction, as occurs with horizontal axis small wind turbines (HASWT). In addition, VASWTs have a minor acoustic impact with respect to HASWTs. The aim of this paper is to study the interactions that take place between a 1.2 kW, vertical axis, Darrieus VASWT turbine and a small, experimental building, in order to analyze the noise and the vibrations transmitted to the structure. One method to damp the vibrations is then assessed through spectral analysis of data acquired through accelerometers located both in the mast of the wind turbine and at the building walls. The results confirm the usefulness of dampers to increase the building comfort regarding vibrations.

Highlights

The recent trend in energy production is supporting large industrial intensive power plants and possibly locating small-scale energy systems close to the end users
One of the most used method to study rotating machines is order tracking (OT) analysis [27]. This mathematical instrument turns out to be useful when a non-stationary vibrating phenomena has to be correlated with rotational speed varying in time, as for example the wind turbine rotor speed
An advantage of OT techniques is that a spectral analysis was not carried out with respect to an absolute frequency scale but relatively to passing frequency of the shaft: in this way is possible to clearly isolate all the phenomena that are proportional to the rotating speed

Summary

Introduction

The recent trend in energy production is supporting large industrial intensive power plants and possibly locating small-scale energy systems close to the end users. Placing small wind turbines close to final users, mostly in urban locations or in off-grid configuration [2,3], means that the airflow affecting the turbines is strongly turbulent [4,5,6,7], rapidly variable in speed and direction with the presence of boundary layer effect caused by building, obstacles and a lower rotor altitude. For these reasons, the choice of the appropriate wind turbine model for on-site generation (OSG) applications is a crucial step in order to produce energy efficiently. In large wind farms horizontal axis models are the most used because of higher efficiency [4] and a better return on investment [4], for OSG purposes

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