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  • 1
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    Initial Assessment of Open Rotor Propulsion Applied to an Advanced Single-Aisle Aircraft (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Application of high speed, advanced turboprops, or propfans, to subsonic transport aircraft received significant attention and research in the 1970s and 1980s when fuel efficiency was the driving focus of aeronautical research. Recent volatility in fuel prices and concern for aviation s environmental impact have renewed interest in unducted, open rotor propulsion, and revived research by NASA and a number of engine manufacturers. Unfortunately, in the two decades that have passed since open rotor concepts were thoroughly investigated, NASA has lost experience and expertise in this technology area. This paper describes initial efforts to re-establish NASA s capability to assess aircraft designs with open rotor propulsion. Specifically, methodologies for aircraft-level sizing, performance analysis, and system-level noise analysis are described. Propulsion modeling techniques have been described in a previous paper. Initial results from application of these methods to an advanced single-aisle aircraft using open rotor engines based on historical blade designs are presented. These results indicate open rotor engines have the potential to provide large reductions in fuel consumption and emissions. Initial noise analysis indicates that current noise regulations can be met with old blade designs and modern, noiseoptimized blade designs are expected to result in even lower noise levels. Although an initial capability has been established and initial results obtained, additional development work is necessary to make NASA s open rotor system analysis capability on par with existing turbofan analysis capabilities.
    Keywords: Aircraft Design, Testing and Performance
    Type: NF1676L-12112 , 11th AIAA Aviation Technology, Integration, and Operations (ATIO) Conference; Sep 20, 2011 - Sep 22, 2011; Virginia Beach, VA; United States
    Format: application/pdf
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  • 2
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    A Subsonic Aircraft Design Optimization With Neural Network and Regression Approximators (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Flight-Optimization-System (FLOPS) code encountered difficulty in analyzing a subsonic aircraft. The limitation made the design optimization problematic. The deficiencies have been alleviated through use of neural network and regression approximations. The insight gained from using the approximators is discussed in this paper. The FLOPS code is reviewed. Analysis models are developed and validated for each approximator. The regression method appears to hug the data points, while the neural network approximation follows a mean path. For an analysis cycle, the approximate model required milliseconds of central processing unit (CPU) time versus seconds by the FLOPS code. Performance of the approximators was satisfactory for aircraft analysis. A design optimization capability has been created by coupling the derived analyzers to the optimization test bed CometBoards. The approximators were efficient reanalysis tools in the aircraft design optimization. Instability encountered in the FLOPS analyzer was eliminated. The convergence characteristics were improved for the design optimization. The CPU time required to calculate the optimum solution, measured in hours with the FLOPS code was reduced to minutes with the neural network approximation and to seconds with the regression method. Generation of the approximators required the manipulation of a very large quantity of data. Design sensitivity with respect to the bounds of aircraft constraints is easily generated.
    Keywords: Aircraft Design, Testing and Performance
    Type: NASA/TM-2004-213059 , AIAA Paper 2004-4606 , E-14504 , 10th Multidisciplinary Analysis and Optimization Conference; Aug 30, 2004 - Sep 01, 2004; Albany, NY; United States
    Format: application/pdf
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  • 3
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    A Probabilistic Assessment of NASA Ultra-Efficient Engine Technologies for a Large Subsonic Transport (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: NASA's Ultra Efficient Engine Technology (UEET) program features advanced aeropropulsion technologies that include highly loaded turbomachinery, an advanced low-NOx combustor, high-temperature materials, intelligent propulsion controls, aspirated seal technology, and an advanced computational fluid dynamics (CFD) design tool to help reduce airplane drag. A probabilistic system assessment is performed to evaluate the impact of these technologies on aircraft fuel burn and NOx reductions. A 300-passenger aircraft, with two 396-kN thrust (85,000-pound) engines is chosen for the study. The results show that a large subsonic aircraft equipped with the UEET technologies has a very high probability of meeting the UEET Program goals for fuel-burn (or equivalent CO2) reduction (15% from the baseline) and LTO (landing and takeoff) NOx reductions (70% relative to the 1996 International Civil Aviation Organization rule). These results are used to provide guidance for developing a robust UEET technology portfolio, and to prioritize the most promising technologies required to achieve UEET program goals for the fuel-burn and NOx reductions.
    Keywords: Aircraft Design, Testing and Performance
    Type: GT2004-53485 , E-14435 , ASME Turbo Expo 2004; Jun 14, 2004 - Jun 17, 2004; Vienna; Austria
    Format: application/pdf
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  • 4
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    Engine Conceptual Design Studies for a Hybrid Wing Body Aircraft (2009)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Worldwide concerns of air quality and climate change have made environmental protection one of the most critical issues in aviation today. NASA's current Fundamental Aeronautics research program is directed at three generations of aircraft in the near, mid and far term, with initial operating capability around 2015, 2020, and 2030, respectively. Each generation has associated goals for fuel burn, NOx, noise, and field-length reductions relative to today's aircrafts. The research for the 2020 generation is directed at enabling a hybrid wing body (HWB) aircraft to meet NASA's aggressive technology goals. This paper presents the conceptual cycle and mechanical designs of the two engine concepts, podded and embedded systems, which were proposed for a HWB cargo freighter. They are expected to offer significant benefits in noise reductions without compromising the fuel burn.
    Keywords: Aircraft Design, Testing and Performance
    Type: GT2009-59568 , E-16910 , ASME Turbo 2009; Jun 08, 2009 - Jun 12, 2009; Florida; United States
    Format: application/pdf
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  • 5
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    Adaptive Engine Technologies for Aviation CO2 Emissions Reduction (2006)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Adaptive turbine engine technologies are assessed for their potential to reduce carbon dioxide emissions from commercial air transports.Technologies including inlet, fan, and compressor flow control, compressor stall control, blade clearance control, combustion control, active bearings and enabling technologies such as active materials and wireless sensors are discussed. The method of systems assessment is described, including strengths and weaknesses of the approach. Performance benefit estimates are presented for each technology, with a summary of potential emissions reduction possible from the development of new, adaptively controlled engine components.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2006-214392 , E-15670 , AIAA Paper 2006-5105 , 42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference; Jul 09, 2006 - Jul 12, 2006; Sacreamento, CA; United States
    Format: application/pdf
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  • 6
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    A Comparative Propulsion System Analysis for the High-Speed Civil Transport (2005)
    In:  CASI
    Details
    Publication Date: 2019-07-11
    Description: Six of the candidate propulsion systems for the High-Speed Civil Transport are the turbojet, turbine bypass engine, mixed flow turbofan, variable cycle engine, Flade engine, and the inverting flow valve engine. A comparison of these propulsion systems by NASA's Glenn Research Center, paralleling studies within the aircraft industry, is presented. This report describes the Glenn Aeropropulsion Analysis Office's contribution to the High-Speed Research Program's 1993 and 1994 propulsion system selections. A parametric investigation of each propulsion cycle's primary design variables is analytically performed. Performance, weight, and geometric data are calculated for each engine. The resulting engines are then evaluated on two airframer-derived supersonic commercial aircraft for a 5000 nautical mile, Mach 2.4 cruise design mission. The effects of takeoff noise, cruise emissions, and cycle design rules are examined.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2005-213414 , E-14934 , HSR007
    Format: application/pdf
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  • 7
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    Advanced Single-Aisle Transport Propulsion Design Options Revisited (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Future propulsion options for advanced single-aisle transports have been investigated in a number of previous studies by the authors. These studies have examined the system level characteristics of aircraft incorporating ultra-high bypass ratio (UHB) turbofans (direct drive and geared) and open rotor engines. During the course of these prior studies, a number of potential refinements and enhancements to the analysis methodology and assumptions were identified. This paper revisits a previously conducted UHB turbofan fan pressure ratio trade study using updated analysis methodology and assumptions. The changes incorporated have decreased the optimum fan pressure ratio for minimum fuel consumption and reduced the engine design trade-offs between minimizing noise and minimizing fuel consumption. Nacelle drag and engine weight are found to be key drivers in determining the optimum fan pressure ratio from a fuel efficiency perspective. The revised noise analysis results in the study aircraft being 2 to 4 EPNdB (cumulative) quieter due to a variety of reasons explained in the paper. With equal core technology assumed, the geared engine architecture is found to be as good as or better than the direct drive architecture for most parameters investigated. However, the engine ultimately selected for a future advanced single-aisle aircraft will depend on factors beyond those considered here.
    Keywords: Aircraft Propulsion and Power
    Type: AIAA Paper 2013-4330 , NF1676L-16101 , AIAA Aviation Technology, Integration, and Operations (ATIO) Conference; Aug 12, 2013 - Aug 14, 2013; Los Angeles, CA; United States
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  • 8
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    Analysis of Turbofan Design Options for an Advanced Single-Aisle Transport Aircraft (2009)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The desire for higher engine efficiency has resulted in the evolution of aircraft gas turbine engines from turbojets, to low bypass ratio, first generation turbofans, to today's high bypass ratio turbofans. It is possible that future designs will continue this trend, leading to very-high or ultra-high bypass ratio (UHB) engines. Although increased bypass ratio has clear benefits in terms of propulsion system metrics such as specific fuel consumption, these benefits may not translate into aircraft system level benefits due to integration penalties. In this study, the design trade space for advanced turbofan engines applied to a single-aisle transport (737/A320 class aircraft) is explored. The benefits of increased bypass ratio and associated enabling technologies such as geared fan drive are found to depend on the primary metrics of interest. For example, bypass ratios at which fuel consumption is minimized may not require geared fan technology. However, geared fan drive does enable higher bypass ratio designs which result in lower noise. Regardless of the engine architecture chosen, the results of this study indicate the potential for the advanced aircraft to realize substantial improvements in fuel efficiency, emissions, and noise compared to the current vehicles in this size class.
    Keywords: Aircraft Propulsion and Power
    Type: LF99-8327 , 9th AIAA Aviation Technology, Integration, and Operations Conference; Sep 21, 2009 - Sep 24, 2009; Hilton Head, SC; United States
    Format: application/pdf
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