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Active Flow and Combustion Control 2021
The book reports on the latest theoretical and experimental findings in the field of active flow and combustion control, in the context of energy conversion for power and propulsion systems. It covers new developments in actuator technology and sensing, robust and optimal open- and closed-loop control, model reduction for control purposes, and unsteady turbine cooling and performance, among other relevant topics. Gathering contributions to the Active Flow and Combustion Control (AFCC 2021), held virtually on September 28-29, 2021, from the Technische Universität Berlin, Germany, this book describes research that has been carried out within, and supported by, the collaborative research center SFB 1029 on “Substantial efficiency increase in gas turbines through direct use of coupled unsteady combustion and flow dynamics”, and funded by the German Research Foundation (DFG). It highlights theoretical and practical aspects, and corresponding solutions, that are important for the development of future energy conversion systems, thus offering a timely guide for researchers and practitioners in the field of aeronautics, turbomachinery, control and combustion.
New Results in Numerical and Experimental Fluid Mechanics XIV
This book offers timely insights into research on numerical and experimental fluid mechanics and aerodynamics, mainly for (but not limited to) aerospace applications. It reports on findings by members of the Deutsche Strömungsmechanische Arbeitsgemeinschaft, STAB (German Aerodynamics/Fluid Mechanics Association) and the Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal Oberth e.V., DGLR (German Society for Aeronautics and Astronautics) and covers both nationally and EC-funded projects. Continuing on the tradition of the previous volumes, the book highlights innovative solutions, promoting translation from fundamental research to industrial applications. It addresses academics and professionals in the field of aeronautics, astronautics, ground transportation, and energy alike.
Investigations on the current and future use of radio frequency allocations for small satellite operations
Global radio frequency spectrum use for satellite communication is a present-day challenge that has been aggravated by the increased launch of small satellites during the past 15 years. This thesis aims to examine both regulatory and technical aspects of spectrum use. The focus of this examination is on frequency bands that are commonly used by small satellites and on those bands that might be applicable for future use. The thesis content is subdivided into three parts. The first part presents the needed background on small satellites as well as the regulatory environment for small satellites. The second part gives insight into the results of a theoretical assessment of current and future sm...
Flight mechanics and flight control for a multibody aircraft
Aircraft operating as so-called High Altitude Platform Systems (HAPS) have been considered as a complementary technology to satellites since several years. These aircraft can be used for similar communication and monitoring tasks while operating at a fraction of the cost. Such concepts have been successfully tested. Those include the AeroVironment Helios and the Airbus Zephyr, with an endurance of nearly 624 hours (26 days). All these HAPS aircraft have a high-aspect-ratio wing using lightweight construction. In gusty atmosphere, this results in high bending moments and high structural loads, which can lead to overloads. Aircraft crashes, for example from Google’s Solara 50 or Facebook’s...
Contributions to the advance of the integration density of CubeSats
This thesis investigates potential technologies to increase the integration density of CubeSats. Observations of the CubeSat market and missions are recorded in order to derive design criteria for high performance single unit CubeSats. A promising approach to increased integration density is relocation of the components of multiple satellite subsystems to form a highly integrated, multi-functional solar panel. Eligible components are usually allocated to the communication system, the electric power system, or the attitude determination and control system. In a joint research project, development, optimization, and miniaturization of those components in order to form a highly integrated, mult...
A flexible attitude control system for three-axis stabilized nanosatellites
This thesis investigates a new concept for the flexible design and verification of an ADCS for a nanosatellite platform. In order to investigate guidelines for the design of a flexible ADCS, observations of the satellite market and missions are recorded. Following these observations, the author formulates design criteria which serve as a reference for the conceptual design of the flexible ADCS. The research of the thesis was carried out during the development of TU Berlin's nanosatellite platform TUBiX20 and its first two missions, TechnoSat and TUBIN. TUBiX20 targets modularity, reuse and dependability as main design goals. Based on the analysis of design criteria for a flexible ADCS, these...
Contributions to on-board navigation on 1U CubeSats
This thesis investigates the use of GNSS receivers on 1U CubeSats, using the example of BEESAT-4 and BEESAT-9. The integration of such a device on satellites enables highly precise time synchronization, position acquisition and orbit determination and prediction The application fields that depend on an accurate attitude control and orbit determination system and can also be processed by CubeSats are highlighted. Therefore the state of the art of GNSS receivers is described, which are suitable for the use on satellites and could be integrated into 1U CubeSats. Further on it is investigated which subsystems of a small satellite are particularly affected and what the special challenges are to r...
Überwachung hybrider Schrägkugellager in Luftfahrttriebwerken
Es wird ein Konzept zur Überwachung hybrider Schrägkugellager für Hauptwellen von Luftfahrttriebwerken vorgestellt. Gezeigt wird die Auswirkung der Interaktion geschädigter keramischer Wälzkörper mit den Stahllaufringen. Es werden Schwachstellen bei der Berechnung von Kugelrotationsfrequenzen besprochen und Möglichkeiten, die Resultate der Berechnung zu verbessern. Im Vergleich werden Vorteile bei der Erfassung von Lagerschäden durch die Messung von Körperschall gegenüber der Messung von Vibrationen oder der Messung von Metallpartikeln im Öl gezeigt. Nachgewiesen wird, dass eine Erkennung von Lagerschäden zu einem frühen Zeitpunkt im Schädigungsprozess möglich ist. Ein besonde...
Beitrag zur numerischen Berechnung rotierender Strukturen im Strömungsfeld hochbelasteter axialer Turboverdichter und Analyse der Entstehungsmechanismen
Das Ziel dieser Arbeit bestand darin, das Phänomen der Rotierenden Instabilität, welches experimentell an dem Ringgitterwindkanal der Universität Kassel bestätigt wurde, mit Hilfe numerischer Simulation abzubilden und weiter zu untersuchen.
