摘要 :
Reducing aviation climate impact is a priority for the stakeholders of the sector, but doing so requires increased investments and progress in aircraft technology, low-carbon fuels, and operations. Aircraft are generally very vers...
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Reducing aviation climate impact is a priority for the stakeholders of the sector, but doing so requires increased investments and progress in aircraft technology, low-carbon fuels, and operations. Aircraft are generally very versatile, leading to missions that are far from the ones they have been designed and optimized for. A potential lever for CO_2 reduction in aviation is to have an overall fleet that is better tailored and optimized for the needs of the air transport system. Aircraft are generally designed with a set of top-level aircraft requirements to ensure they match operational constraints. This paper proposes to relax these requirements to assess the effects of lower-range, slower and modified payload aircraft, and evaluate the potential gains for the air transport system. Per-passenger and kilometer fuel burn and operating costs of several modified aircraft are compared with a baseline aircraft using a payload-range response surface. It allows a quick estimation of any mission fuel burn and operating cost. United States-wide operations emissions abatement potential is assessed by replacing the reference fleet with the newly designed aircraft when it is more efficient. Marginal fuel burn gains of 6 % are found when a shorter-range aircraft is designed. An illustrative slower open-rotor aircraft would not significantly increase its operating costs. Increasing the capacity offers both cost and fuel burn reductions but decreases the operating versatility.
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Using low-carbon energies is a major lever to reduce the CO_2 emissions of aviation. Some low-carbon energy carriers consist in fuels that are drop-in and require few modifications to current aircraft, like biofuels and electrofue...
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Using low-carbon energies is a major lever to reduce the CO_2 emissions of aviation. Some low-carbon energy carriers consist in fuels that are drop-in and require few modifications to current aircraft, like biofuels and electrofuels. Hydrogen is another low-carbon fuel that would be relevant in the long term only since it requires significant aircraft modifications (non-drop-in fuel). In both cases, several production pathways exist with radically different impacts in terms of cost of production and life-cycle CO_2 emissions. Literature is already exhaustive on prospective decarbonization scenarios for aviation and low-carbon fuel production cost estimates. In this paper, an open-source simulation framework named CAST is enhanced by a module that links low-carbon fuels production cost to their respective consumption in given scenarios. Hence, the cost of a custom decarbonization scenario is evaluated. Results show that the cost of the integration of low-carbon fuels in this scenario would represent around 40 % of airlines revenues in 2050, while the energy demand growth would necessitate important capital investments, regularly increasing to 130 Bn € in 2050. A sensitivity analysis shows that these cost estimates are subject to large uncertainties.
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The transportation sector, and more particularly the aviation sector, is regularly pointed at and considered as a significant contributor to today's climate change because of its greenhouse gas emissions growth. As global awarenes...
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The transportation sector, and more particularly the aviation sector, is regularly pointed at and considered as a significant contributor to today's climate change because of its greenhouse gas emissions growth. As global awareness and concerns about the aviation environmental impacts are growing, a need to quantify them has arisen especially when considering alternative energy sources. Many methods exist to provide some models and key figures. Among them, Life Cycle Assessment (LCA) allows studying the stages of a product life cycle and quantifying their impacts on several environmental indicators. In this paper, an LCA of aircraft similar to an Airbus A320 is developed and computed for identifying the most impacting stages of its life. The results obtained are used to develop and implement an environmental module in FAST-OAD, an overall aircraft design tool composed of several typical modules (aerodynamics, propulsion, structure, etc.). Finally, an application of the method is achieved for an aircraft that uses different incorporation rates of biofuels. Results show that the biofuels of second generation (used cooking oil) can reduce CO_2 effects almost by half if mixed with 50 % of kerosene, or by 90 % if completely incorporated. Furthermore, one last study is achieved regarding an aircraft designed for a specific range of 2500 NM for two different operational missions of 2750 NM and 500 NM. Results show that the shorter range deteriorates its performances in terms of CO_2 effects per RPK by 18% when compared to the 2750 NM range.
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In the context of necessary reduction of the environmental footprint of aviation, the concept of More Electric Aircraft (MEA) appears to be one of the leading research directions to increase the future airliners performance and th...
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In the context of necessary reduction of the environmental footprint of aviation, the concept of More Electric Aircraft (MEA) appears to be one of the leading research directions to increase the future airliners performance and thus reduce their energy consumption and emissions. However, the electrification leads to an increase in the number of heat sources that have to be thermally managed due to their intricate integration within the airframe. Therefore, thermal management system technologies and strategies must be investigated to ensure the cooling of equipment exposed to thermal stress. In this paper, three technologies are considered: scoop and flush air inlets, an air-air heat exchanger system with electric fan, and an air-source heat pump. For each of them, models are established in order to estimate their mass, their possible additional drag and their contribution to electrical consumption, which are key outputs for overall aircraft design. Finally, a comparison is made for different quantities of heat to be dissipated to determine which technology leads to the least fuel penalty at aircraft level. Air-source heat pump and flush inlet systems are found to be the solutions that cause the least fuel penalty.
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摘要 :
In the context of necessary reduction of the environmental footprint of aviation, the concept of More Electric Aircraft (MEA) appears to be one of the leading research directions to increase the future airliners performance and th...
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In the context of necessary reduction of the environmental footprint of aviation, the concept of More Electric Aircraft (MEA) appears to be one of the leading research directions to increase the future airliners performance and thus reduce their energy consumption and emissions. However, the electrification leads to an increase in the number of heat sources that have to be thermally managed due to their intricate integration within the airframe. Therefore, thermal management system technologies and strategies must be investigated to ensure the cooling of equipment exposed to thermal stress. In this paper, three technologies are considered: scoop and flush air inlets, an air-air heat exchanger system with electric fan, and an air-source heat pump. For each of them, models are established in order to estimate their mass, their possible additional drag and their contribution to electrical consumption, which are key outputs for overall aircraft design. Finally, a comparison is made for different quantities of heat to be dissipated to determine which technology leads to the least fuel penalty at aircraft level. Air-source heat pump and flush inlet systems are found to be the solutions that cause the least fuel penalty.
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摘要 :
We present an imaging technique allowing locating a small perturbation appearing in a multiple scattering environment. This technique is based on the direct dependence in space and time of the coda decorrelation resulting from the...
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We present an imaging technique allowing locating a small perturbation appearing in a multiple scattering environment. This technique is based on the direct dependence in space and time of the coda decorrelation resulting from the apparition of a supplementary scatterer, which one wishes to image. The inverse problem solution - the location of the defect - is obtained using a maximum likelihood computation. The LOCADIFF technique has been applied to locate a millimeter change in concrete using ultrasounds with a precision of the order of one centimeter. The size of the defect is comparable to that of the heterogeneities constituting the sample.
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摘要 :
We present an imaging technique allowing locating a small perturbation appearing in a multiple scattering environment. This technique is based on the direct dependence in space and time of the coda decorrelation resulting from the...
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We present an imaging technique allowing locating a small perturbation appearing in a multiple scattering environment. This technique is based on the direct dependence in space and time of the coda decorrelation resulting from the apparition of a supplementary scatterer, which one wishes to image. The inverse problem solution - the location of the defect - is obtained using a maximum likelihood computation. The LOCADIFF technique has been applied to locate a millimeter change in concrete using ultrasounds with a precision of the order of one centimeter. The size of the defect is comparable to that of the heterogeneities constituting the sample.
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摘要 :
This article presents an imaging technique to locate a weak perturbation in a multiple scattering environment. We focus on concrete probed by ultrasound. We derive a formula to predict the spatiotemporal decorrelation of diffuse c...
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This article presents an imaging technique to locate a weak perturbation in a multiple scattering environment. We focus on concrete probed by ultrasound. We derive a formula to predict the spatiotemporal decorrelation of diffuse coda waves induced by an extra scatterer. We solve the inverse problem with a maximum likelihood approach. Using elastic waves in the 50-400 kHz frequency band, we recover the position of millimetric holes drilled in a concrete sample with a precision of a few centimeters.
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