The small wind turbine field lab extensive field tests for small wind turbines

This paper describes the research possibilities at the Small Wind Turbine Field Lab and the involved research groups of Ghent University, covering different aspects of a small wind energy system. In contrast to large and medium-sized wind turbines, small wind turbines are still plagued by relatively high production and purchase costs, and low reliability and energy yield. Furthermore, most of them have not been subjected to a field test program. Power-Link, the energy knowledge platform of Ghent University, has for three years operated a modest field test site for small wind turbines, that drew the attention of a lot of manufacturers of small wind turbines. In response, Ghent University decided to launch the Small Wind Turbine Field Lab (SWT Field Lab), to subject small wind turbines to more extensive field tests. Now not only the energy yield is tested, but also topics such as grid integration, structural strength, noise propagation, generator and drive train design and tower construction are studied. All of these parameters are correlated with meteorological data measured on-site

Use of high resolution sonar for near-turbine fish observations (DIDSON) - We@Sea 2007-002

In this study we investigate small scale distribution of pelagic fish within a windfarm by means of a high resolution sonar (DIDSON, Dual frequency IDentification SONar; Soundmetrics). In addition we assess the bias of small scale variations induced by the effects of wind turbines (monopiles) on distribution of the pelagic fish community in the hydro acoustic surveys carried out on the OWEZ Near Shore Wind farm (NSW)

Wind Energy and the Turbulent Nature of the Atmospheric Boundary Layer

Wind turbines operate in the atmospheric boundary layer, where they are exposed to the turbulent atmospheric flows. As the response time of wind turbine is typically in the range of seconds, they are affected by the small scale intermittent properties of the turbulent wind. Consequently, basic features which are known for small-scale homogeneous isotropic turbulence, and in particular the well-known intermittency problem, have an important impact on the wind energy conversion process. We report on basic research results concerning the small-scale intermittent properties of atmospheric flows and their impact on the wind energy conversion process. The analysis of wind data shows strongly intermittent statistics of wind fluctuations. To achieve numerical modeling a data-driven superposition model is proposed. For the experimental reproduction and adjustment of intermittent flows a so-called active grid setup is presented. Its ability is shown to generate reproducible properties of atmospheric flows on the smaller scales of the laboratory conditions of a wind tunnel. As an application example the response dynamics of different anemometer types are tested. To achieve a proper understanding of the impact of intermittent turbulent inflow properties on wind turbines we present methods of numerical and stochastic modeling, and compare the results to measurement data. As a summarizing result we find that atmospheric turbulence imposes its intermittent features on the complete wind energy conversion process. Intermittent turbulence features are not only present in atmospheric wind, but are also dominant in the loads on the turbine, i.e. rotor torque and thrust, and in the electrical power output signal. We conclude that profound knowledge of turbulent statistics and the application of suitable numerical as well as experimental methods are necessary to grasp these unique features (...)Comment: Accepted by the Journal of Turbulence on May 17, 201

Economic considerations of utilizing small wind generators

The economic feasibility of small wind generators is compared to that of solar cells, primary batteries, thermoelectric generators, and engine generators. It is shown that small wind generator plants offer an attractive alternative to primary battery systems and constantly running engines to generate power in remote areas. The limitation is an annual average wind velocity of at least 9 to 10 mph. Presently available units are most useful in the average load range of 10 to 1000 watts

2D wind clumping in hot, massive stars from hydrodynamical line-driven instability simulations using a pseudo-planar approach

Context: Clumping in the radiation-driven winds of hot, massive stars arises naturally due to the strong, intrinsic instability of line-driving (the `LDI'). But LDI wind models have so far mostly been limited to 1D, mainly because of severe computational challenges regarding calculation of the multi-dimensional radiation force. Aims: To simulate and examine the dynamics and multi-dimensional nature of wind structure resulting from the LDI. Methods: We introduce a `pseudo-planar', `box-in-a-wind' method that allows us to efficiently compute the line-force in the radial and lateral directions, and then use this approach to carry out 2D radiation-hydrodynamical simulations of the time-dependent wind. Results: Our 2D simulations show that the LDI first manifests itself by mimicking the typical shell-structure seen in 1D models, but how these shells then quickly break up into complex 2D density and velocity structures, characterized by small-scale density `clumps' embedded in larger regions of fast and rarefied gas. Key results of the simulations are that density-variations in the well-developed wind statistically are quite isotropic and that characteristic length-scales are small; a typical clump size is ~0.01R at 2R, thus resulting also in rather low typical clump-masses ~10^17 g. Overall, our results agree well with the theoretical expectation that the characteristic scale for LDI-generated wind-structure is of order the Sobolev length. We further confirm some earlier results that lateral `filling-in' of radially compressed gas leads to somewhat lower clumping factors in 2D simulations than in comparable 1D models. We conclude by discussing an extension of our method toward rotating LDI wind models that exhibit an intriguing combination of large- and small-scale structure extending down to the wind base.Comment: 9 pages, 7 figures + 1 Appendix with 1 figure. Recommended for publication in A&

The small wind turbine field lab

The emerging market of small wind turbines (SWT) is characterised by a large variety of turbine types as well as turbine performance. The abundance of more ‘exotic’ types of vertical axis wind turbines (VAWT) next to the more traditional horizontal axis wind turbines (HAWT) shows that this market is still developing. However, some technologies have proven to possess the same potential typically only found in larger wind turbines. To study the (lack of) performance of current small wind turbine but also to demonstrate their potential, Ghent University decided to launch the Small Wind Turbine Field Lab (SWT Field Lab). This fully scientifically equipped field lab, funded by the Hercules Foundation, offers the possibility to not only monitor the energy yield of the turbine, but also collect information on how to optimise the grid integration, measure mechanical stress and structural strength of turbine components, assess the generator design and tower construction, perform acoustic measurements and finding ways to reduce noise production, even simulate siting of wind turbines, e.g. in rural areas or on industrial parks. All of these parameters are correlated with meteorological data measured on-site. The field lab, based in the inner port of Ostend, provides provisions for placement of up to ten small wind turbines, with seven turbines already partaking in the field trials. The project members aim to use the project results to identify and remove performance limiting factors in the design of small wind turbine, and to demonstrate the feasibility of using small wind turbines for decentralised renewable energy production. With this and similar research projects, the emerging market of small wind turbines can grow beyond its current state of infancy, comparable to the market evolution of large wind turbines

Outdoor lighting wind generators with basalt fiber composite blades

Small wind generators are successfully applied for outdoor lighting on highways, parks, seaside boulevards. We developed technologies that gives an opportunity to manufacture wind rotor, the main element of this type of generators, using basalt fiber composite, and to manufacture generator itself. Based on the research data we manufactured 200 w capacity wind generator equipped with basalt fiber composite blades