TY - CHAP A1 - Hallmann, Marcus A1 - Heidecker, Ansgar A1 - Schlotterer, Markus A1 - Dachwald, Bernd T1 - GTOC8: results and methods of team 15 DLR T2 - 26th AAS/AIAA Space Flight Mechanics Meeting, Napa, CA N2 - This paper describes the results and methods used during the 8th Global Trajectory Optimization Competition (GTOC) of the DLR team. Trajectory optimization is crucial for most of the space missions and usually can be formulated as a global optimization problem. A lot of research has been done to different type of mission problems. The most demanding ones are low thrust transfers with e.g. gravity assist sequences. In that case the optimal control problem is combined with an integer problem. In most of the GTOCs we apply a filtering of the problem based on domain knowledge. Y1 - 2016 N1 - 26th AAS/AIAA Space Flight Mechanics Meeting, February 14-18, 2016, Napa, California, U.S.A. Napa, CA ER - TY - JOUR A1 - Hammer, Thorben A1 - Quitter, Julius A1 - Mayntz, Joscha A1 - Bauschat, J.-Michael A1 - Dahmann, Peter A1 - Götten, Falk A1 - Hille, Sebastian A1 - Stumpf, Eike T1 - Free fall drag estimation of small-scale multirotor unmanned aircraft systems using computational fluid dynamics and wind tunnel experiments JF - CEAS Aeronautical Journal N2 - New European Union (EU) regulations for UAS operations require an operational risk analysis, which includes an estimation of the potential danger of the UAS crashing. A key parameter for the potential ground risk is the kinetic impact energy of the UAS. The kinetic energy depends on the impact velocity of the UAS and, therefore, on the aerodynamic drag and the weight during free fall. Hence, estimating the impact energy of a UAS requires an accurate drag estimation of the UAS in that state. The paper at hand presents the aerodynamic drag estimation of small-scale multirotor UAS. Multirotor UAS of various sizes and configurations were analysed with a fully unsteady Reynolds-averaged Navier–Stokes approach. These simulations included different velocities and various fuselage pitch angles of the UAS. The results were compared against force measurements performed in a subsonic wind tunnel and provided good consistency. Furthermore, the influence of the UAS`s fuselage pitch angle as well as the influence of fixed and free spinning propellers on the aerodynamic drag was analysed. Free spinning propellers may increase the drag by up to 110%, depending on the fuselage pitch angle. Increasing the fuselage pitch angle of the UAS lowers the drag by 40% up to 85%, depending on the UAS. The data presented in this paper allow for increased accuracy of ground risk assessments. KW - Multirotor UAS KW - Drag estimation KW - CFD KW - Wind tunnel experiments KW - Wind milling Y1 - 2023 U6 - https://doi.org/10.1007/s13272-023-00702-w SN - 1869-5590 (Online) SN - 1869-5582 (Print) N1 - Corresponding author: Thorben Hammer PB - Springer CY - Wien ER - TY - BOOK A1 - Harder, Jörn T1 - Simulation lokaler Fließvorgänge in Polykristallen Y1 - 1997 SN - 3-920395-27-1 N1 - Serie Braunschweiger Schriften zur Mechanik , 28 ; Zugl.: Braunschweig, Techn. Univ., Diss., 1996 PB - Mechanik-Zentrum der Technischen Universität CY - Braunschweig ER - TY - BOOK A1 - Harder, Jörn T1 - Zur Messung von Werkstoffparametern im Torsionsschwingversuch Y1 - 1990 CY - Braunschweig ER - TY - JOUR A1 - Harder, Jörn T1 - A crystallographic model for the study of local deformation processes in polycrystals JF - International journal of plasticity. 15 (1999), H. 6 Y1 - 1999 SN - 0749-6419 N1 - Online: http://opus.tu-bs.de/opus/volltexte/1999/10/pdf/10_1.pdf SP - 605 EP - 624 ER - TY - CHAP A1 - Haugg, Albert Thomas A1 - Kreyer, Jörg A1 - Kemper, Hans A1 - Hatesuer, Katerina A1 - Esch, Thomas T1 - Heat exchanger for ORC. adaptability and optimisation potentials T2 - IIR International Rankine 2020 Conference N2 - The recovery of waste heat requires heat exchangers to extract it from a liquid or gaseous medium into another working medium, a refrigerant. In Organic Rankine Cycles (ORC) on Combustion Engines there are two major heat sources, the exhaust gas and the water/glycol fluid from the engine’s cooling circuit. A heat exchanger design must be adapted to the different requirements and conditions resulting from the heat sources, fluids, system configurations, geometric restrictions, and etcetera. The Stacked Shell Cooler (SSC) is a new and very specific design of a plate heat exchanger, created by AKG, which allows with a maximum degree of freedom the optimization of heat exchange rate and the reduction of the related pressure drop. This optimization in heat exchanger design for ORC systems is even more important, because it reduces the energy consumption of the system and therefore maximizes the increase in overall efficiency of the engine. Y1 - 2020 U6 - https://doi.org/10.18462/iir.rankine.2020.1224 N1 - IIR International Rankine 2020 Conference - Heating, Cooling, Power Generation. Glasgow, 2020. ER - TY - BOOK A1 - Havermann, Marc T1 - Development of a free flight force measuring (FFM) technique at the ISL shock tube laboratory : 25th International Symposium on Shock Waves, ISSW25, Bangalore, India, July 17 - 22, 2005 / Institut Franco-Allemand de Recherches de Saint-Louis. Seiler, F. ; Mathieu, G. ; George, A. ; Srulijes, J. ; Sauerwein, B. ; Havermann, M. Y1 - 2005 N1 - Publication / Institut Franco-Allemand de Recherches de Saint-Louis ; 620 PB - ISL CY - Saint-Louis ER - TY - JOUR A1 - Havermann, Marc T1 - Systematic Shock Tube Experiments on Vortex Ring Generation and Propagation / Havermann, M. ; Kainuma, M. ; Takayama, K. JF - Shock waves : proceedings of the 25th International Symposium on Shock Waves-ISSW25, July 17 - 22, 2005, Bangalore, India / ed.: G. Jagadeesh Y1 - 2006 SN - 978-81-7371571-6 N1 - International Symposium on Shock Waves ; 25 (Bangalore) : 2005.07.17-22 ISSW ; 25 (Bangalore) : 2005.07.17-22 PB - Universities Pr. CY - Hyderabad ER - TY - BOOK A1 - Havermann, Marc T1 - Strahlmischung und Druckrückgewinn in Überschall-Innenströmungen Y1 - 2000 SN - 3-86073-761-9 N1 - Aachener Beiträge zum Maschinenbau ; 2 ; Zugl. Aachen, Techn. Hochsch., Diss., 1999 PB - Mainz CY - Aachen ER - TY - BOOK A1 - Havermann, Marc T1 - PIV measurements in shock tunnels : PivNet 2, Final Workshop, Göttingen, 07. - 08.09.2006 Y1 - 2006 N1 - Publication / Institut Franco-Allemand de Recherches de Saint Louis ; 644 PB - ISL CY - Saint-Louis ER -