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  • Aircraft Propulsion and Power
  • 2005-2009  (49)
  • 1950-1954  (5)
  • 2008  (49)
  • 1953  (5)
  • 1936
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  • 2005-2009  (49)
  • 1950-1954  (5)
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  • 1
    Publikationsdatum: 2018-06-06
    Beschreibung: System studies have shown the benefits of reducing blade tip clearances in modern turbine engines. Minimizing blade tip clearances throughout the engine will contribute materially to meeting NASA s Ultra-Efficient Engine Technology (UEET) turbine engine project goals. NASA GRC is examining two candidate approaches including rub-avoidance and regeneration which are explained in subsequent slides.
    Schlagwort(e): Aircraft Propulsion and Power
    Materialart: 2007 NASA Seal/Secondary Air System Workshop; 101-123; NASA/CP-2008-215263/VOL1
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2018-06-06
    Beschreibung: As the aviation industry moves toward higher efficiency electrical power generation, all electric aircraft, or zero emissions and more quiet aircraft, fuel cells are sought as the technology that can deliver on these high expectations. The hybrid solid oxide fuel cell system combines the fuel cell with a micro-turbine to obtain up to 70% cycle efficiency, and then distributes the electrical power to the loads via a power distribution system. The challenge is to understand the dynamics of this complex multidiscipline system and the design distributed controls that take the system through its operating conditions in a stable and safe manner while maintaining the system performance. This particular system is a power generation and a distribution system, and the fuel cell and micro-turbine model fidelity should be compatible with the dynamics of the power distribution system in order to allow proper stability and distributed controls design. The novelty in this paper is that, first, the case is made why a high fidelity fuel cell mode is needed for systems control and stability designs. Second, a novel modeling approach is proposed for the fuel cell that will allow the fuel cell and the power system to be integrated and designed for stability, distributed controls, and other interface specifications. This investigation shows that for the fuel cell, the voltage characteristic should be modeled but in addition, conservation equation dynamics, ion diffusion, charge transfer kinetics, and the electron flow inherent impedance should also be included.
    Schlagwort(e): Aircraft Propulsion and Power
    Materialart: Journal of Fuel Cell Science and Technology; Volume 5
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2018-06-06
    Beschreibung: The usage and integrated vehicle health management of the NASA C-17. Propulsion health management flight objectives for the aircraft include mapping of the High Pressure Compressor in order to calibrate a Pratt and Whitney engine model and the fusion of data collected from existing sensors and signals to develop models, analysis methods and information fusion algorithms. An additional health manage flight objective is to demonstrate that the Commercial Modular Aero-Propulsion Systems Simulation engine model can successfully execute in real time onboard the C-17 T-1 aircraft using engine and aircraft flight data as inputs. Future work will address aircraft durability and aging, airframe health management, and propulsion health management research in the areas of gas path and engine vibration.
    Schlagwort(e): Aircraft Propulsion and Power
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Publikationsdatum: 2019-07-12
    Beschreibung: A vane has an airfoil shell and a spar within the shell. The vane has an outboard shroud at an outboard end of the shell and an inboard platform at an inboard end of the shell. The spar has a first chamber essentially along the suction side and a second chamber along the pressure side opposite the first chamber.
    Schlagwort(e): Aircraft Propulsion and Power
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Publikationsdatum: 2019-07-12
    Beschreibung: Key aspects of the design of sealing systems for On Rotor Combustion/Wave Rotor (ORC/WR) systems were addressed. ORC/WR systems generally fit within a broad class of pressure gain Constant Volume Combustors (CVCs) or Pulse Detonation Combustors (PDCs) which are currently being considered for use in many classes of turbine engines for dramatic efficiency improvement. Technology readiness level of this ORC/WR approaches are presently at 2.0. The results of detailed modeling of an ORC/WR system as applied to a regional jet engine application were shown to capture a high degree of pressure gain capabilities. The results of engine cycle analysis indicated the level of specific fuel consumption (SFC) benefits to be 17 percent. The potential losses in pressure gain due to leakage were found to be closely coupled to the wave processes at the rotor endpoints of the ORC/WR system. Extensive investigation into the sealing approaches is reported. Sensitivity studies show that SFC gains of 10 percent remain available even when pressure gain levels are highly penalized. This indicates ORC/WR systems to have a high degree of tolerance to rotor leakage effects but also emphasizes their importance. An engine demonstration of an ORC/WR system is seen as key to progressing the TRL of this technology. An industrial engine was judged to be a highly advantageous platform for demonstration of a first generation ORC/WR system. Prior to such a demonstration, the existing NASA pressure exchanger wave rotor rig was identified as an opportunity to apply both expanded analytical modeling capabilities developed within this program and to identify and fix identified leakage issues existing within this rig. Extensive leakage analysis of the rig was performed and a detailed design of additional sealing strategies for this rig was generated.
    Schlagwort(e): Aircraft Propulsion and Power
    Materialart: NASA/CR-2008-215479 , E-16656
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Publikationsdatum: 2019-07-12
    Beschreibung: Computational fluid dynamics (CFD) analysis has been performed to study the plume effects on sonic boom signature for isolated nozzle configurations. The objectives of these analyses were to provide comparison to past work using modern CFD analysis tools, to investigate the differences of high aspect ratio nozzles to circular (axisymmetric) nozzles, and to report the effects of underexpanded nozzle operation on boom signature. CFD analysis was used to address the plume effects on sonic boom signature from a baseline exhaust nozzle. Near-field pressure signatures were collected for nozzle pressure ratios (NPRs) between 6 and 10. A computer code was used to extrapolate these signatures to a ground-observed sonic boom N-wave. Trends show that there is a reduction in sonic boom N-wave signature as NPR is increased from 6 to 10. The performance curve for this supersonic nozzle is flat, so there is not a significant loss in thrust coefficient as the NPR is increased. As a result, this benefit could be realized without significant loss of performance. Analyses were also collected for a high aspect ratio nozzle based on the baseline design for comparison. Pressure signatures were collected for nozzle pressure ratios from 8 to 12. Signatures were nearly twice as strong for the two-dimensional case, and trends also show a reduction in sonic boom signature as NPR is increased from 8 to 12. As low boom designs are developed and improved, there will be a need for understanding the interaction between the aircraft boat tail shocks and the exhaust nozzle plume. These CFD analyses will provide a baseline study for future analysis efforts.
    Schlagwort(e): Aircraft Propulsion and Power
    Materialart: NASA/TM-2008-215414 , AIAA Paper 2008-3729 , E-16535-1
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Publikationsdatum: 2019-07-12
    Beschreibung: Helicopter Health Usage Monitoring Systems (HUMS) have potential for providing data to support increasing the service life of a dynamic mechanical component in the transmission of a helicopter. Data collected can demonstrate the HUMS condition indicator responds to a specific component fault with appropriate alert limits and minimal false alarms. Defining thresholds for specific faults requires a tradeoff between the sensitivity of the condition indicator (CI) limit to indicate damage and the number of false alarms. A method using Receiver Operating Characteristic (ROC) curves to assess CI performance was demonstrated using CI data collected from accelerometers installed on several UH60 Black Hawk and AH64 Apache helicopters and an AH64 helicopter component test stand. Results of the analysis indicate ROC curves can be used to reliably assess the performance of commercial HUMS condition indicators to detect damaged gears and bearings in a helicopter transmission.
    Schlagwort(e): Aircraft Propulsion and Power
    Materialart: NASA/TM-2008-215262 , E-16530
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Publikationsdatum: 2019-07-12
    Beschreibung: Flaps (or half wedges) attached to the sides of a pylon are shown to result in a small but clear noise benefit. Noise radiated towards the ground is reduced apparently through a deflection and thickening of the fan stream underneath. Based on results from the current as well as concurrent investigations at the University of California at Irvine, it is recommended that further tests in a larger facility simulating realistic engine conditions be considered.
    Schlagwort(e): Aircraft Propulsion and Power
    Materialart: NASA/TM-2008-215288 , E-16562
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2019-07-12
    Beschreibung: The objective is to provide turbine-cooling technologies to meet Propulsion 21 goals related to engine fuel burn, emissions, safety, and reliability. Specifically, the GE Aviation (GEA) Advanced Turbine Cooling and Thermal Management program seeks to develop advanced cooling and flow distribution methods for HP turbines, while achieving a substantial reduction in total cooling flow and assuring acceptable turbine component safety and reliability. Enhanced cooling techniques, such as fluidic devices, controlled-vortex cooling, and directed impingement jets, offer the opportunity to incorporate both active and passive schemes. Coolant heat transfer enhancement also can be achieved from advanced designs that incorporate multi-disciplinary optimization of external film and internal cooling passage geometry.
    Schlagwort(e): Aircraft Propulsion and Power
    Materialart: NASA/CR-2008-215236 , E-16495
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2019-07-12
    Beschreibung: The objective of the Advanced Turbine Cooling and Thermal Management program is to develop intelligent control and distribution methods for turbine cooling, while achieving a reduction in total cooling flow and assuring acceptable turbine component safety and reliability. The program also will develop embedded sensor technologies and cooling system models for real-time engine diagnostics and health management. Both active and passive control strategies will be investigated that include the capability of intelligent modulation of flow quantities, pressures, and temperatures both within the supply system and at the turbine component level. Thermal management system concepts were studied, with a goal of reducing HPT blade cooling air supply temperature. An assessment will be made of the use of this air by the active clearance control system as well. Turbine component cooling designs incorporating advanced, high-effectiveness cooling features, will be evaluated. Turbine cooling flow control concepts will be studied at the cooling system level and the component level. Specific cooling features or sub-elements of an advanced HPT blade cooling design will be downselected for core fabrication and casting demonstrations.
    Schlagwort(e): Aircraft Propulsion and Power
    Materialart: NASA/CR-2008-215238 , E-16497
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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