Abstract:The Energy System Transition in Aviation research project of the Aeronautics Research Center Niedersachsen (NFL) searches for potentially game-changing technologies to reduce the carbon footprint of aviation by promoting and enabling new propulsion and drag reduction technologies. The greatest potential for aerodynamic drag reduction is seen in laminar flow control by boundary layer suction. While most of the research so far has been on partial laminarization by application of Natural Laminar Flow (NLF) and Hybrid Laminar Flow Control (HLFC) to wings, complete laminarization of wings, tails and fuselages promises much higher gains. The potential drag reduction and suction requirements, including the necessary compressor power, are calculated on component level using a flow solver with viscid/inviscid coupling and a 3D Reynolds-Averaged Navier-Stokes (RANS) solver. The effect on total aircraft drag is estimated for a state-of-the-art mid-range aircraft configuration using preliminary aircraft design methods, showing that total cruise drag can be halved compared to today's turbulent aircraft.
Within the German BNF research project a generic twin-engine configuration with an active high-lift wing and modern turboprop engines is investigated. This paper deals with high fidelity RANS computations of the wind tunnel configuration measured in previous measurement campaigns. The simulation data is in good agreement with the experiment. The presented investigations focus on the jet flow due to the internally blown flap and the propeller slipstream.
The German Bürgernahes Flugzeug (Citizen-Oriented Airplane) research program advances technologies for high-lift systems using circulation control Coandă-type flaps. The interaction of these high-lift systems with a propeller engine is the subject of the present work. A large and complex wind-tunnel model equipped with an active high-lift system and a powered propeller was designed, manufactured and instrumented. The wind-tunnel data show the potentials of the active high-lift system in three-dimensional wing applications. The results characterize and quantify the interactions between a propeller and a high-lift wing by using systematic variations of blowing momentum and propeller thrust. The results represent a unique database for future efforts to improve the efficiency of active lift and for validation of numerical simulation methods.
Due to increasing airport congestion the German research project 'Bürgernahes Flugzeug' (BNF, citizen friendly airplane) investigates the potential of aircraft concepts for a possible future air transportation system integrating small airports. Key technologies in aerodynamics for developing new generation quiet, efficient, short take-off and landing (QESTOL) aircraft are studied through the synergistic exploitationof Computational Fluid Dynamics (CFD) and new wind tunnel data. One subject of the conducted investigations is a ninebladed high power propeller mounted in tractor configuration on a wing that is equipped with an active gapless high-lift system. As the aerodynamic focus of the BNF project is on the interaction between the propeller slipstream and the high-lift flowfield, this paper is focussed on the experimental investigation of the propeller performance in comparison with simulation data.
The Render Cache [1,2] allows the interactive display of very large scenes, rendered with complex global illumination models, by decoupling camera movement from the costly scene sampling process. In this paper, the distributed execution of the individual components of the Render Cache on a PC cluster is shown to be a viable alternative to the shared memory implementation.As the processing power of an entire node can be dedicated to a single component, more advanced algorithms may be examined. Modular functional units also lead to increased flexibility, useful in research as well as industrial applications.We introduce a new strategy for view-driven scene sampling, as well as support for multiple camera viewpoints generated from the same cache. Stereo display and a CAVE multi-camera setup have been implemented.The use of the highly portable and inter-operable CORBA networking API simplifies the integration of most existing pixel-based renderers. So far, three renderers (C++ and Java) have been adapted to function within our framework.
Usably secure ad-hoc device pairing fosters connectivity with hardware which is difficult to access (e.g., implanted) and grants convenience for ad-hoc short-term on-off pairing patterns (e.g. shared public domain). Examples are medical devices or fitness equipment. We present CardioID, an approach to extract features from heart rate variability for secure pairing keys that change with the randomness inherited in heart operation. Our processing chain is compatible with electrocardiogram (ECG, voltage), as well as ballistocardiogram (BCG, acceleration) type signals. Dissimilarities in locally generated sequences are accounted for using fuzzy cryptography exploiting Bose-Chaudhuri-Hocquenghem (BCH) codes. We propose a quantization to derive secure keys for cross BCG-ECG device pairing from heart-rate variability and analyze the performance in (inter-and intra-subject) BCG-to-ECG pairing. A secure communication protocol for Body Area Networks (BAN) is discussed. The attack surface of the protocol is analyzed, and we conduct a video-based attack study. In addition, two case studies with 5 (laboratory) and 20 (controlled in-field) subjects were conducted.INDEX TERMS Ballistocardiogram (BCG), bioinformatic, body area network, devices pairing, electrocardiogram (ECG), healthcare, usable security
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