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The dynamic inflow effect describes the unsteady aerodynamic response to fast changes in rotor loading due to the inertia of the wake. Fast changes in turbine loading due to pitch actuation or rotor speed transients lead to load overshoots. The phenomenon is suspected to be also relevant for gust situations; however, this was never shown, and thus the actual load response is also unknown. The paper’s objectives are to prove and explain the dynamic inflow effect due to gusts, and compare and subsequently improve a typical dynamic inflow engineering model to the measurements. An active grid is used to impress a 1.8m diameter model turbine with rotor uniform gusts of the wind tunnel flow. The influence attributed to the dynamic inflow effect is isolated from the comparison of two experimental cases. Firstly, dynamic measurements of loads and radially resolved axial velocities in the rotor plane during a gust situation are performed. Secondly, corresponding quantities are linearly interpolated for the gust wind speed from lookup tables with steady operational points. Furthermore,simulations with a typical blade element momentum code and a higher-fidelity free-vortex wake model are performed. Both the experiment and higher-fidelity model show a dynamic inflow effect due to gusts in the loads and axial velocities. An amplification of induced velocities causes reduced load amplitudes. Consequently, fatigue loading would be lower. This amplification originates from wake inertia. It is influenced by the coherent gust pushed through the rotor like a turbulent box. The wake is superimposed on that coherent gust box, and thus the inertia of the wake and consequently also the flow in the rotor plane is affected. Contemporary dynamic inflow models inherently assume a constant wind velocity. They filter the induced velocity and thus cannot predict the observed amplification of the induced velocity. The commonly used Øye engineering model predicts increased gust load amplitudes and thus higher fatigue loads. With an extra filter term on the quasi-steady wind velocity, the qualitative behaviour observed experimentally and numerically can be caught. In conclusion, these new experimental findings on dynamic inflow due to gusts and improvements to the Øye model enable improvements in wind turbine design by less conservative fatigue loads.
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This study explores the shape-morphing behavior of 4D-printed structures made from Polylactic Acid (PLA), a prominent bio-sourced shape-memory polymer. Focusing on the response of these structures to thermal stimuli, this research investigates how various printing parameters influence their morphing capabilities. The experimental approach integrates design and slicing, printing using fused deposition modeling (FDM), and a post-printing activation phase in a controlled laboratory environment. This process aims to replicate the external stimuli that induce shape morphing, highlighting the dynamic potential of 4D printing. Utilizing Taguchi’s Design of Experiments (DoE), this study examines the effects of printing speed, layer height, layer width, nozzle temperature, bed temperature, and activation temperature on the morphing behavior. The analysis includes precise measurements of deformation parameters, providing a comprehensive understanding of the morphing process. Regression models demonstrate strong correlations with observed data, suggesting their effectiveness in predicting responses based on control parameters. Additionally, finite element analysis (FEA) modeling successfully predicts the performance of these structures, validating its application as a design tool in 4D printing. This research contributes to the understanding of 4D printing dynamics and offers insights for optimizing printing processes to harness the full potential of shape-morphing materials. It sets a foundation for future research, particularly in exploring the relationship between printing parameters and the functional capabilities of 4D-printed structures.
The dynamic inflow effect denotes the unsteady aerodynamic response to fast changes in rotor loading due to a gradual adaption of the wake. This does lead to load overshoots. The objective of the paper was to increase the understanding of that effect based on pitch step experiments on a 1.8 m diameter model wind turbine, which are performed in the large open jet wind tunnel of ForWind – University of Oldenburg. The flow in the rotor plane is measured with a 2D laser Doppler anemometer, and the dynamic wake induction factor transients in axial and tangential direction are extracted. Further, integral load measurements with strain gauges and hot-wire measurements in the near and close far wake are performed. The results show a clear gradual decay of the axial induction factors after a pitch step, giving the first direct experimental evidence of dynamic inflow due to pitch steps. Two engineering models are fitted to the induction factor transients to further investigate the relevant time constants of the dynamic inflow process. The radial dependency of the axial induction time constants as well as the dependency on the pitch direction is discussed. It is confirmed that the nature of the dynamic inflow decay is better described by two rather than only one time constant. The dynamic changes in wake radius are connected to the radial dependency of the axial induction transients. In conclusion, the comparative discussion of inductions, wake deployment and loads facilitate an improved physical understanding of the dynamic inflow process for wind turbines. Furthermore, these measurements provide a new detailed validation case for dynamic inflow models and other types of simulations.
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An important line of research within the Center of Expertise HAN BioCentre is the development of the nematode Caenorhabditis elegans as an animal testing replacement organism. In the context of this, us and our partners in the research line Elegant! (project number. 2014-01-07PRO) developed reliable test protocols, data analysis strategies and new technology, to determine the expected effects of exposure to specific substances using C. elegans. Two types of effects to be investigated were envisaged, namely: i) testing of possible toxicity of substances to humans; and ii) testing for potential health promotion of substances for humans. An important deliverable was to show that the observed effects in the nematode can indeed be translated into effects in humans. With regard to this aspect, partner Preventimed has conducted research in obesity patients during the past year into the effect of a specific cherry extract that was selected as promising on the basis of the study with C. elegans. This research is currently being completed and a scientific publication will have to be written. The Top Up grant is intended to support the publication of the findings from Elegant! and also to help design experimental protocols that enable students to become acquainted with alternative medical testing systems to reduce the use of laboratory animals during laboratory training.
Lipids, proteins and biological active compounds that are present in insects can serve as nutrient source for poultry production. Because of the potential benefit effects of using insects as feed additives, we must consider the effects of gut microbiome on the insect affects itself, and the expected effect on the microbiome of the broilers that consume these insects. This is specifically important in the situation where live insects are fed to poultry, without prior processing. In this proposal we describe to study whether larvae fed to broilers will affect their microbiome in a positive way for practical applications in poultry industry. Hence, a pilot proof-of-concept study will be carried out as basis for a follow-up proposal for a larger project in the future, that we also like to set-up within this project. In that follow-up proposal, focus will be on the effect of different substrates for insects, on the insect microbiome, to spike insects with specific bacteria and to track their microbiome dynamics over time, and the effect of these insects used as a feed additive on the broiler gut microbiome. This study will provide results on if live Black Soldier Fly larvae (BSFL) can affect the broiler gut microbiome in a positive way, and relevant outcomes will be exploited in a follow-up research proposal in which these effects will be unraveled in detail for adoption by the industry. The project is a collaboration between cooperative insect company RavenFeed and NGN Pro-active both with knowledge on BSFL rearing, Wageningen Bioveterinary Research (WBVR) with knowledge on insect diseases and microbiome analysis, Schothorst Feed Research (SFR) highly experienced in poultry nutrition research and having unique poultry facilities, and Aeres University of Applied Sciences Dronten (AHD) with research facilities for BSFL rearing under experimental conditions.
Introduction The research group Biobased Resources & Energy (BRE) of Avans focusses on recovery of valuable building blocks from low-value solid and liquid residual streams from agriculture, households and industries. For the valorisation of these residual streams, BRE looks into different biological, chemical and mechanical processes. One of the main issues in the utilisation of residual streams is economic feasibility and the recovery of multiple resources from one residual stream. Using membrane technologies in combination with biological, chemical and/or mechanical processes could offer great opportunities. Central Research Question What is the applicability of membrane technologies for valorisation of different residual streams and is it possible to integrate membrane technology in current and new biorefining projects of research group BRE: Set-up In order to reach the goal of this postdoc, 4 research questions will be answered using literature search, experimentation and modelling: 1) What membrane methods are currently (commercially) available to enhance the results of current projects in research group BRE? 2) What are the essential technical parameters for membrane separation and how can these be optimized? 3) What is the economic impact of using membrane technology in recovery of valuable building blocks from residual streams? 4) What are the effects of using membranes instead of or complementary to currently used methods on the sustainability of valorisation of residual streams? Cooperation The postdoc and the research group BRE want to extend the contact and research cooperation with (regional) businesses and (applied) universities and support and facilitate the introduction and further development of membrane technologies in the curriculum of different Avans study programmes. This will be done via internships, minor projects (together with businesses) and development of study material for courses and trainings.