Wind turbines are usually clustered in wind farms which causes the downstream turbines to operate in the turbulent wakes of upstream turbines. As turbulence is directly related to increased fatigue loads, knowledge of the turbulence in the wake and its evolution are important. Therefore, the main objective of this study is a comprehensive exploration of the turbulence evolution in the wind turbine’s wake to identify characteristic turbulence regions. For this, we present an experimental study of three model wind turbine wake scenarios that were scanned with hot-wire anemometry with a very high downstream resolution. The model wind turbine was exposed to three inflows: laminar inflow as a reference case, a central wind turbine wake, and half of the wake of an upstream turbine. A detailed turbulence analysis reveals four downstream turbulence regions by means of the mean velocity, variance, turbulence intensity, energy spectra, integral and Taylor length scales, and the Castaing parameter that indicates the intermittency, or gustiness, of turbulence. In addition, a wake core with features of homogeneous isotropic turbulence and a ring of high intermittency surrounding the wake can be identified. The results are important for turbulence modeling in wakes and optimization of wind farm wake control
MULTIFILE
Innovation in the 21st century has been moving continuously away from the model embraced in the last century, which was characterized as a profit-oriented and silo-targeted one. Currently, the logic is being driven towards “the social” sense and value of the transformation within the reality of complexity and the continuous necessity of designing and re-designing concepts towards sustainability of a different level. The underlying motive of innovation has been for long perceived as generating predominantly economic value. However, co-designing the society in the future is now being transformed into tackling social challenges in a multi-layered complexity scenario. Thus, there has been identified a need to find complementary ways to nurture innovation, generating social and public value based on interdependence and the emergence of interrelated and constantly networking actors.
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The Interreg Europe eBussed project supports the transition of European regions towards low carbon mobility and more efficient transport. The regions involved are Turku (Finland), Hamburg (Germany), Utrecht (The Netherlands), Livorno (Italy), South Transdanubia (Hungary) and Gozo island in Malta. It promotes the uptake of e-busses in new regions and supports the expansion of existing e-fleets. Within the project, there are four thematic working groups formed that aim at delivering a best practices report and policy recommendations to be used in the partner regions. Thematic Working Group 4 (TWG4) focusses on the topics of Procurement, Tendering and Costs of e-busses. As a starting point for TWG4, the value chain for e-bus public transport per region has been mapped. By mapping how the value chain for e-bus public transport works and defining the nature of the issues, problems or maybe challenges per region can be better understood.