@inproceedings{WeissAbanteribaEsch2007, author = {Weiss, Alexander and Abanteriba, Sylvester and Esch, Thomas}, title = {Investigation of Flow Separation Inside a Conical Rocket Nozzle With the Aid of an Annular Cross Flow}, series = {Proceedings of the ASME/JSME 2007 5th Joint Fluids Engineering Conference. Volume 1: Symposia, Parts A and B}, booktitle = {Proceedings of the ASME/JSME 2007 5th Joint Fluids Engineering Conference. Volume 1: Symposia, Parts A and B}, publisher = {American Society of Mechanical Engineers (ASME)}, address = {New York}, isbn = {0-7918-4288-6}, doi = {10.1115/FEDSM2007-37387}, pages = {1861 -- 1871}, year = {2007}, abstract = {Flow separation is a phenomenon that occurs in all kinds of supersonic nozzles sometimes during run-up and shut-down operations. Especially in expansion nozzles of rocket engines with large area ratio, flow separation can trigger strong side loads that can damage the structure of the nozzle. The investigation presented in this paper seeks to establish measures that may be applied to alter the point of flow separation. In order to achieve this, a supersonic nozzle was placed at the exit plane of the conical nozzle. This resulted in the generation of cross flow surrounding the core jet flow from the conical nozzle. Due to the entrainment of the gas stream from the conical nozzle the pressure in its exit plane was found to be lower than that of the ambient. A Cold gas instead of hot combustion gases was used as the working fluid. A mathematical simulation of the concept was validated by experiment. Measurements confirmed the simulation results that due to the introduction of a second nozzle the pressure in the separated region of the conical nozzle was significantly reduced. It was also established that the boundary layer separation inside the conical nozzle was delayed thus allowing an increased degree of overexpansion. The condition established by the pressure measurements was also demonstrated qualitatively using transparent nozzle configurations.}, language = {en} } @inproceedings{NiederwestbergSchneiderTeixeiraBouraetal.2022, author = {Niederwestberg, Stefan and Schneider, Falko and Teixeira Boura, Cristiano Jos{\´e} and Herrmann, Ulf}, title = {Introduction to a direct irradiated transparent tube particle receiver}, series = {SOLARPACES 2020}, booktitle = {SOLARPACES 2020}, number = {2445 / 1}, publisher = {AIP conference proceedings / American Institute of Physics}, address = {Melville, NY}, isbn = {978-0-7354-4195-8}, issn = {1551-7616 (online)}, doi = {10.1063/5.0086735}, pages = {9 Seiten}, year = {2022}, abstract = {New materials often lead to innovations and advantages in technical applications. This also applies to the particle receiver proposed in this work that deploys high-temperature and scratch resistant transparent ceramics. With this receiver design, particles are heated through direct-contact concentrated solar irradiance while flowing downwards through tubular transparent ceramics from top to bottom. In this paper, the developed particle receiver as well as advantages and disadvantages are described. Investigations on the particle heat-up characteristics from solar irradiance were carried out with DEM simulations which indicate that particle temperatures can reach up to 1200 K. Additionally, a simulation model was set up for investigating the dynamic behavior. A test receiver at laboratory scale has been designed and is currently being built. In upcoming tests, the receiver test rig will be used to validate the simulation results. The design and the measurement equipment is described in this work.}, language = {en} } @inproceedings{HuthElsenHartwigetal.2006, author = {Huth, Thomas and Elsen, Olaf and Hartwig, Christoph and Esch, Thomas}, title = {Innovative modular valve trains for 2015 - logistic benefits by EMVT}, series = {IFAC Proceedings Volumes, Volume 39, Issue 3}, booktitle = {IFAC Proceedings Volumes, Volume 39, Issue 3}, publisher = {Elsevier}, address = {Amsterdam}, doi = {10.3182/20060517-3-FR-2903.00172}, pages = {315 -- 320}, year = {2006}, abstract = {In this paper the way to a 5-day-car with respect to a modular valve train systems for spark ignited combustion engines is shown. The necessary product diversity is shift from mechanical or physical components to software components. Therefore, significant improvements of logistic indicators are expected and shown. The working principle of a camless cylinder head with respect to an electromagnetical valve train (EMVT) is explained and it is demonstrated that shifting physical diversity to software is feasible. The future design of combustion engine systems including customisation can be supported by a set of assistance tools which is shown exemplary.}, language = {en} } @incollection{EnglaenderKaminskiSchuba2022, author = {Engl{\"a}nder, Jacques and Kaminski, Lars and Schuba, Marko}, title = {Informationssicherheitsmanagement}, series = {Digitalisierungs- und Informationsmanagement}, booktitle = {Digitalisierungs- und Informationsmanagement}, publisher = {Springer Vieweg}, address = {Berlin}, isbn = {978-3-662-63757-9}, doi = {10.1007/978-3-662-63758-6_15}, pages = {373 -- 398}, year = {2022}, abstract = {Daten und Informationen sind die wichtigsten Ressourcen vieler Unternehmen und m{\"u}ssen daher entsprechend gesch{\"u}tzt werden. Getrieben durch die erh{\"o}hte Vernetzung von Informationstechnologie, die h{\"o}here Offenheit infolge datengetriebener Dienstleistungen und eine starke Zunahme an Datenquellen, r{\"u}cken die Gefahren von Informationsdiebstahl, -manipulation und -verlust in den Fokus von produzierenden Unternehmen. Auf dem Weg zum lern- und wandlungsf{\"a}higen Unternehmen kann dies zu einem großen Hindernis werden, da einerseits zu hohe Sicherheitsanforderungen neue Entwicklungen beschr{\"a}nken, andererseits wegen des Mangels an ausreichenden Informationssicherheitskonzepten Unternehmen weniger Innovationen wagen. Deshalb bedarf es individuell angepasster Konzepte f{\"u}r die Bereiche IT-Security, IT-Safety und Datenschutz f{\"u}r vernetzte Produkte, Produktion und Arbeitspl{\"a}tze. Bei der Entwicklung und Durchsetzung dieser Konzepte steht der Faktor Mensch im Zentrum aller {\"U}berlegungen. In diesem Kapitel wird dargestellt, wie der Faktor Mensch bei der Erstellung von Informationssicherheitskonzepten in verschiedenen Phasen zu beachten ist. Beginnend mit der Integration von Informationssystemen und damit verbundenen Sicherheitsmaßnahmen, {\"u}ber die Administration, bis hin zur Anwendung durch den Endnutzer, werden Methoden beschrieben, die den Menschen, verbunden mit seinem Mehrwert wie auch den Risiken, einschließen. Dabei werden sowohl Grundlagen aufgezeigt als auch Konzepte vorgestellt, mit denen Entscheider in der Unternehmens-IT Leitlinien f{\"u}r die Informationssicherheit festlegen k{\"o}nnen.}, language = {de} } @inproceedings{NeuJanserKhatibietal.2016, author = {Neu, Eugen and Janser, Frank and Khatibi, Akbar A. and Orifici, Adrian C.}, title = {In-flight vibration-based structural health monitoring of aircraft wings}, series = {30th Congress of the internatonal council of the aeronautical sciences : 25.-30. September 2016, Daejeon, Korea}, booktitle = {30th Congress of the internatonal council of the aeronautical sciences : 25.-30. September 2016, Daejeon, Korea}, pages = {10 Seiten}, year = {2016}, abstract = {This work presents a methodology for automated damage-sensitive feature extraction and anomaly detection under multivariate operational variability for in-flight assessment of wings. The method uses a passive excitation approach, i. e. without the need for artificial actuation. The modal system properties (natural frequencies and damping ratios) are used as damage-sensitive features. Special emphasis is placed on the use of Fiber Bragg Grating (FBG) sensing technology and the consideration of Operational and Environmental Variability (OEV). Measurements from a wind tunnel investigation with a composite cantilever equipped with FBG and piezoelectric sensors are used to successfully detect an impact damage. In addition, the feasibility of damage localisation and severity estimation is evaluated based on the coupling found between damageand OEV-induced feature changes.}, language = {en} } @inproceedings{ThomaFisherBraun2020, author = {Thoma, Andreas and Fisher, Alex and Braun, Carsten}, title = {Improving the px4 avoid algorithm by bio-inspired flight strategies}, series = {DLRK2020 - „Luft- und Raumfahrt - Verantwortung in allen Dimensionen"}, booktitle = {DLRK2020 - „Luft- und Raumfahrt - Verantwortung in allen Dimensionen"}, doi = {10.25967/530183}, pages = {10 Seiten}, year = {2020}, language = {en} } @article{ThomaGardiFisheretal.2024, author = {Thoma, Andreas and Gardi, Alessandro and Fisher, Alex and Braun, Carsten}, title = {Improving local path planning for UAV flight in challenging environments by refining cost function weights}, series = {CEAS Aeronautical Journal}, journal = {CEAS Aeronautical Journal}, publisher = {Springer}, address = {Wien}, issn = {1869-5590 (eISSN)}, doi = {10.1007/s13272-024-00741-x}, pages = {12 Seiten}, year = {2024}, abstract = {Unmanned Aerial Vehicles (UAV) constantly gain in versatility. However, more reliable path planning algorithms are required until full autonomous UAV operation is possible. This work investigates the algorithm 3DVFH* and analyses its dependency on its cost function weights in 2400 environments. The analysis shows that the 3DVFH* can find a suitable path in every environment. However, a particular type of environment requires a specific choice of cost function weights. For minimal failure, probability interdependencies between the weights of the cost function have to be considered. This dependency reduces the number of control parameters and simplifies the usage of the 3DVFH*. Weights for costs associated with vertical evasion (pitch cost) and vicinity to obstacles (obstacle cost) have the highest influence on the failure probability of the local path planner. Environments with mainly very tall buildings (like large American city centres) require a preference for horizontal avoidance manoeuvres (achieved with high pitch cost weights). In contrast, environments with medium-to-low buildings (like European city centres) benefit from vertical avoidance manoeuvres (achieved with low pitch cost weights). The cost of the vicinity to obstacles also plays an essential role and must be chosen adequately for the environment. Choosing these two weights ideal is sufficient to reduce the failure probability below 10\%.}, language = {en} } @article{GoettenHavermannBraunetal.2020, author = {G{\"o}tten, Falk and Havermann, Marc and Braun, Carsten and Marino, Matthew and Bil, Cees}, title = {Improved Form Factor for Drag Estimation of Fuselages with Various Cross Sections}, series = {Journal of Aircraft}, journal = {Journal of Aircraft}, publisher = {AIAA}, address = {Reston, Va.}, issn = {1533-3868}, doi = {10.2514/1.C036032}, pages = {1 -- 13}, year = {2020}, abstract = {The paper presents an aerodynamic investigation of 70 different streamlined bodies with fineness ratios ranging from 2 to 10. The bodies are chosen to idealize both unmanned and small manned aircraft fuselages and feature cross-sectional shapes that vary from circular to quadratic. The study focuses on friction and pressure drag in dependency of the individual body's fineness ratio and cross section. The drag forces are normalized with the respective body's wetted area to comply with an empirical drag estimation procedure. Although the friction drag coefficient then stays rather constant for all bodies, their pressure drag coefficients decrease with an increase in fineness ratio. Referring the pressure drag coefficient to the bodies' cross-sectional areas shows a distinct pressure drag minimum at a fineness ratio of about three. The pressure drag of bodies with a quadratic cross section is generally higher than for bodies of revolution. The results are used to derive an improved form factor that can be employed in a classic empirical drag estimation method. The improved formulation takes both the fineness ratio and cross-sectional shape into account. It shows superior accuracy in estimating streamlined body drag when compared with experimental data and other form factor formulations of the literature.}, language = {en} } @inproceedings{SchwagerAngeleNourietal.2022, author = {Schwager, Christian and Angele, Florian and Nouri, Bijan and Schwarzb{\"o}zl, Peter and Teixeira Boura, Cristiano Jos{\´e} and Herrmann, Ulf}, title = {Impact of DNI forecast quality on performance prediction for a commercial scale solar tower: Application of nowcasting DNI maps to dynamic solar tower simulation}, series = {SolarPACES 2022 conference proceedings}, booktitle = {SolarPACES 2022 conference proceedings}, number = {1}, publisher = {TIB Open Publishing}, address = {Hannover}, issn = {2751-9899 (online)}, doi = {10.52825/solarpaces.v1i.675}, pages = {9 Seiten}, year = {2022}, abstract = {Concerning current efforts to improve operational efficiency and to lower overall costs of concentrating solar power (CSP) plants with prediction-based algorithms, this study investigates the quality and uncertainty of nowcasting data regarding the implications for process predictions. DNI (direct normal irradiation) maps from an all-sky imager-based nowcasting system are applied to a dynamic prediction model coupled with ray tracing. The results underline the need for high-resolution DNI maps in order to predict net yield and receiver outlet temperature realistically. Furthermore, based on a statistical uncertainty analysis, a correlation is developed, which allows for predicting the uncertainty of the net power prediction based on the corresponding DNI forecast uncertainty. However, the study reveals significant prediction errors and the demand for further improvement in the accuracy at which local shadings are forecasted.}, language = {en} } @inproceedings{PetersonRoethUibel2017, author = {Peterson, Leif Arne and R{\"o}th, Thilo and Uibel, Thomas}, title = {Holzwerkstoffe in Karosseriestrukturen}, series = {Tagungsband Aachener Holzbautagung 2017}, booktitle = {Tagungsband Aachener Holzbautagung 2017}, editor = {Uibel, Thormas and Peterson, Leif Arne and Baumann, Marcus}, issn = {2197-4489}, pages = {34 -- 45}, year = {2017}, language = {de} }