Piloted Simulation of the Rotorcraft Wind Turbine Wake Interaction during Hover and Transit Flights

Helicopters are used for offshore wind farms for maintenance and support flights. The number of helicopter operations is increasing with the expansion of offshore wind energy, which stresses the point that the current German regulations have not yet been validated through scientific analysis. A collaborative research project between DLR, the Technical University of Munich, the University of Stuttgart and the University of Tübingen has been conducted to examine the sizes of the flight corridors on offshore wind farms and the lateral safety clearance for helicopter hoist operations at offshore wind turbines. This paper details the results of piloted helicopter simulations in a realistic offshore wind farm scenario. The far-wake of rotating wind turbines and the near-wake of non-rotating wind turbines have been simulated with high-fidelity computational fluid dynamics under realistic turbulent inflow conditions. The resulting flow fields have been processed by superposition during piloted simulations in the research flight simulator AVES to examine the flight corridors in transit flights and the lateral safety clearance in hovering flights. The results suggest a sufficient size for the flight corridor and sufficient lateral safety clearance at the offshore wind turbines in the considered scenarios

OC6 project phase III : validation of the aerodynamic loading on a wind turbine rotor undergoing large motion caused by a floating support structure

This paper provides a summary of the work done within Phase III of the Offshore Code Comparison, Collaboration, Continued, with Correlation and unCertainty project (OC6), under International Energy Agency Wind Task 30. This phase focused on validating the aerodynamic loading on a wind turbine rotor undergoing large motion caused by a floating support structure. Numerical models of the Danish Technical University 10-MW reference wind turbine were validated using measurement data from a 1:75 scale test performed during the UNsteady Aerodynamics for FLOating Wind (UNAFLOW) project and a follow-on experimental campaign, both performed at the Politecnico di Milano wind tunnel. Validation of the models was performed by comparing the loads for steady (fixed platform) and unsteady wind conditions (harmonic motion of the platform). For the unsteady wind conditions, the platform was forced to oscillate in the surge and pitch directions under several frequencies and amplitudes. These oscillations result in a wind variation that impacts the rotor loads (e.g., thrust and torque). For the conditions studied in these tests, the system mainly described a quasi-steady aerodynamic behavior. Only a small hysteresis in airfoil performance undergoing angle of attack variations in attached flow was observed. During the experiments, the rotor speed and blade pitch angle were held constant. However, in real wind turbine operating conditions, the surge and pitch variations would result in rotor speed variations and/or blade pitch actuations depending on the wind turbine controller region that the system is operating. Additional simulations with these control parameters were conducted to verify the fidelity between different models. Participant results showed in general a good agreement with the experimental measurements and the need to account for dynamic inflow when there are changes in the flow conditions due to the rotor speed variations or blade pitch actuations in response to surge and pitch motion. Numerical models not accounting for dynamic inflow effects predicted rotor loads that were 9 % lower in amplitude during rotor speed variations and 18 % higher in amplitude during blade pitch actuations

Characterization of the unsteady aerodynamic response of a floating offshore wind turbine

The disruptive potential of floating wind turbines has attracted the interest of both industry and scientific community. Lacking a rigid foundation, such machines are subject to large displacements whose impact on the aerodynamic performance is not yet fully acknowledged. In this work, the unsteady aerodynamic response to an harmonic surge motion of a scaled version of the DTU10MW turbine is investigated in detail. The imposed displacements have been chosen representative of typical platform motions. The results of different numerical models are validated against high fidelity wind tunnel tests specifically focused on the aerodynamics. Also a linear analytical model, relying on the quasi-steady assumption, is presented as a theoretical reference. The unsteady responses are shown to be dominated by the first surge harmonic and a frequency domain characterization, mostly focused on the thrust oscillation, is conducted involving aerodynamic damping and mass parameters. A very good agreement among codes, experiments and quasi-steady theory has been found clarifying some literature doubts. A convenient way to describe the unsteady results in non-dimensional form is proposed, hopefully serving as reference for future work

Development, evaluation and validation of a screening tool for late onset bacteremia in neonates – a pilot study

Abstract Background Clinical and laboratory parameters can aid in the early identification of neonates at risk for bacteremia before clinical deterioration occurs. However, current prediction models have poor diagnostic capabilities. The objective of this study was to develop, evaluate and validate a screening tool for late onset (> 72 h post admission) neonatal bacteremia using common laboratory and clinical parameters; and determine its predictive value in the identification of bacteremia. Methods A retrospective chart review of neonates admitted to a neonatal intensive care unit (NICU) between March 1, 2012 and January 14, 2015 and a prospective evaluation of all neonates admitted between January 15, 2015 and March 30, 2015 were completed. Neonates with late-onset bacteremia (> 72 h after NICU admission) were eligible for inclusion in the bacteremic cohort. Bacteremic patients were matched to non-infected controls on several demographic parameters. A Pearson’s Correlation matrix was completed to identify independent variables significantly associated with infection (p < 0.05, univariate analysis). Significant parameters were analyzed using iterative binary logistic regression to identify the simplest significant model (p < 0.05). The predictive value of the model was assessed and the optimal probability cut-off for bacteremia was determined using a Receiver Operating Characteristic curve. Results Maximum blood glucose, heart rate, neutrophils and bands were identified as the best predictors of bacteremia in a significant binary logistic regression model. The model’s sensitivity, specificity and accuracy were 90, 80 and 85%, respectively, with a false positive rate of 20% and a false negative rate of 9.7%. At the study bacteremia prevalence rate of 51%, the positive predictive value, negative predictive value and negative post-test probability were 82, 89 and 11%, respectively. Conclusion The model developed in the current study is superior to currently published neonatal bacteremia screening tools. Validation of the tool in a historic data set of neonates from our institution will be completed

HeliOW-Abschlussbericht Hubschraubereinsätze in Offshore-Windparks

Das Verbundvorhaben HeliOW (Hubschrauber-Einsätze in Offshore-Windparks) diente der systematischen Untersuchung von Hubschraubereinsätzen in Offshore-Windparks. Dazu wurde schwerpunktmäßig der Einfluss des Nachlaufs einer Windenergieanlage auf die flugdynamische Reaktion eines Hubschraubers untersucht. Das Verbundvorhaben wurde innerhalb des 6. Energieforschungsprogramms im Zeitraum 01/2017 – 03/2020 mit den Verbundpartnern Eberhard Karls Universität Tübingen, Universität Stuttgart, Technische Universität München und dem Deutschen Zentrum für Luft- und Raumfahrt e.V. durchgeführt. Ziel des Projektes war die Erarbeitung wissenschaftlicher rundlagen für die Prüfung und Bereitstellung von Empfehlungen zur Überarbeitung bestehender Regularien für die zuständigen Behörden. In Zusammenarbeit mit den assoziierten Partnern Bundesamt für Seeschifffahrt und Hydrographie (BSH), Luftfahrtbundesamt (LBA), Bundespolizei Fliegergruppe (BPOLFLG), Windpark Heliflight Consulting GmbH (WHC) und Helicopter Travel Munich GmbH (HTM) wurden repräsentative Einsatzszenarien für Hubschraubereinsätze in Offshore-Windparks definiert. Diese waren zum einen der Einflug in den Nachlauf drehender Windenergieanlagen (WEA) und zum anderen der Schwebeflug hinter nichtdrehenden WEA. Es wurde eine multidisziplinäre Simulationskette aufgebaut. Zunächst wurden der Zu- und Nachlauf einer realen Multi-MW WEA mit maritimem Charakter unter Verwendung eines UAS (Unmanned Aircraft System) durch die Universität Tübingen vermessen. Diese Daten wurden von der Universität Stuttgart für die Validierung ihrer WEA-Modelle im CFD (Computational Fluid Dynamics)- Code Flower genutzt. Zusätzlich wurden von der Universität Stuttgart hochaufgelöste CFD-Rechnungen durchgeführt, um den WEA-Nachlauf für die ausgewählten Einsatzszenarien realitätsnah zu berechnen. Ein Meilenstein des Projektes bildete die erfolgreiche Implementierung der resultierenden, sehr großen Geschwindigkeitsfelder (bis zu 128 GB) in die Echtzeitsimulation des AVES (Air Vehicle Simulator) des DLR. Damit konnten Pilotenstudien auf der Bewegtplattform des AVES durchgeführt werden. Hierbei kam die maritime Sichtsimulation des AVES in Verbindung mit einer Nachbildung des Global Tech I Offshore-Windparks zum Einsatz. Im Rahmen der Versuche beurteilten die Piloten die Stärke der Turbulenz sowie ihre Arbeitsbelastung für die ausgewählten Einsatzszenarien. Darüber hinaus wurden die Geschwindigkeitsfelder in die flugdynamische Simulation der Technischen Universität München eingebunden. Anhand der Desktopsimulationen der TUM sowie der Pilotenstudien des DLR war eine Bewertung des Einflusses eines WEA-Nachlaufs auf die Steuerbarkeit des Hubschraubers möglich. Für die untersuchten Einsatzszenarien ergaben sich mit den getroffenen Vereinfachungen der Modellierungen in der Simulationskette und den daraus resultierenden Einschränkungen keine kritischen Flugzustände für den Hubschrauber. Daher kann momentan davon ausgegangen werden, dass die Sicherheitsabstände und Flugverfahren wie sie für die untersuchten Einsatzszenarien derzeit praktiziert werden aus Sicht der Flugsicherheit kein Handlungsbedarf für die Behörden und Operateure zur Überarbeitung besteht. Eine abschließende Bewertung der in HeliOW ermittelten Ergebnisse kann jedoch erst nach einer vollständigen Validierung der im Projekt verwendeten Modelle erfolgen. Dazu müssen experimentelle Daten über das Projekt HeliOW hinaus gewonnen werden

L’habitat et la nécropole du haut Moyen Âge du lieu-dit Le Moulin Vaquet à Honguemare-Guenouville (Eure) : un « village prénormand » du plateau du Roumois. Premiers résultats de la fouille

Sur le plateau du Roumois, le lieu-dit Moulin Vaquet à Honguemare-Guenouville (Eure) était occupé entre le VIIe et le Xe siècle par un village, habitat rural polarisé autour d’une nécropole probablement dominée par une église de bois. La fouille de ce site par la MADE sur 8 600m2 complète celle de l’INRAP à quelques centaines de mètres.Between the 7th and 10th centuries, the “Moulin Vaquet"site, near Honguemare-Guenouville (Eure) on the Roumois Plateau, was occupied by a village – a rural settlement built around a necropolis, likely dominated by a wooden church. The 8,600m2 excavation of the site run by MADE (the Eure archaeological mission) complements the INRAP excavations a few hundred metres away

1987 Persons Award = Prix de l'affaire « personne » 1987 [sic]

Presentation of works by ten women artists in conjunction with awards recognizing women's contributions to Canada. Statements by the artists. Biographical notes