The technical feasibility of operating commercial aircraft on low concentration biodiesel in kerosene blends is reviewed. Although the analysis is preliminary, it seems plausible that a biodiesel component could be introduced without significant modification to aircraft, airport infrastructure, and flight operations. The use of a biodiesel component, even for only a subset of flight operations, would open the possibility of giving all passengers, the world over, regardless of route, the option to pay a premium to make their journey on “green” fuel (actually biodiesel). In this way, the airline industry could recover the additional cost of biodiesel in comparison to kerosene. The costs associated with such a scheme are estimated, as is consumer demand. Although the analysis is preliminary, the scheme appears commercially viable. From a humanitarian and/or environmental perspective, marketing flight on biodiesel as “green air travel” is problematic. On the one hand, the use of biodiesel in aviation would reduce addition of carbon dioxide to the atmosphere and foster development of sustainable technology. On the other hand, it would require that agricultural resources be dedicated to air travel, nominally a luxury, in a world where agricultural resources appear destined to come under increasing strain merely to satisfy humanity’s basic food and energy needs. A preliminary discussion of these issues is presented. It is hoped that this can serve as the starting point for further discussion, at an international level, to reach consensus on whether marketing of flight on biodiesel as “green air travel” should be allowed to proceed, or whether it should be declared unethical.

http://ehsan13967.persiangig.com/document/biodiesel2.pdf

Global sale of green air travel supported using biodiesel

Engineering methods that couple multi-objective optimisation (MOO) techniques with high delity computational tools are expected to minimise the environmental impact of aviation while increasing the growth, with the potential to reveal innovative solutions. In order to mitigate the compromise between computational e ciency and delity, these methods can be accelerated by harnessing the computational e ciency of Graphic Processor Units (GPUs). The aim of the research is to develop a family of engineering methods to support research in aviation with respect to the environmental and economic aspects. In order to reveal the non-dominated trade-o , also known as Pareto Front(PF), among con icting objectives, a MOO algorithm, called Multi-Objective Tabu Search 2 (MOTS2), is developed, benchmarked relative to state-of-the-art methods and accelerated by using GPUs. A prototype uid solver based on GPU is also developed, so as to simulate the mixing capability of a microreactor that could potentially be used in fuel-saving technologies in aviation. By using the aforementioned methods, optimal aircraft trajectories in terms of ight time, fuel consumption and emissions are generated, and alternative designs of a microreactor are suggested, so as to assess the trade-o s between pressure losses and the micro-mixing capability. As a key contribution to knowledge, with reference to competitive optimisers and previous cases, the capabilities of the proposed methodology are illustrated in prototype applications of aircraft trajectory optimisation (ATO) and micromixing optimisation with 2 and 3 objectives, under operational and geometrical constraints, respectively. In the short-term, ATO ought to be applied to existing aircraft. In the long-term, improving the micro-mixing capability of a microreactor is expected to enable the use of hydrogen-based fuel. This methodology is also benchmarked and assessed relative to state-of-the-art techniques in ATO and micro-mixing optimisation with known and unknown trade-o s, whereas the former could only optimise 2 objectives and the latter could not exploit the computational e ciency of GPUs. The impact of deploying on GPUs a micro-mixing ow solver, which accelerates the generation of trade-o against a reference study, and MOTS2, which illustrates the scalability potential, is assessed. With regard to standard analytical function test cases and veri cation cases in MOO, MOTS2 can handle the multi-modality of the trade-o of ZDT4, which is a MOO benchmark function with many local optima that presents a challenge for a state-of-the-art genetic algorithm for ATO, called NSGAMO, based on case studies in the public domain. However, MOTS2 demonstrated worse performance on ZDT3, which is a MOO benchmark function with a discontinuous trade-o , for which NSGAMO successfully captured the target PF. Comparing their overall performance, if the shape of the PF is known, MOTS2 should be preferred in problems with multi-modal trade-o s, whereas NSGAMO should be employed in

Multi-objective optimisation methods applied to aircraft techno-economic and environmental issues

An experimental jet fuel with a -33 C freezing point was chilled in a wing tank simulator with superimposed fuel heating to improve low temperature flowability Heating consisted of circulating a portion of the fuel to an external heat exchanger and returning the heated fuel to the tank Flowability was determined by the mass percent of unpumpable fuel (holdup) left in the simulator upon withdrawal of fuel at the conclusion of testing The study demonstrated that fuel heating is feasible and improves flowability as compared to that of baseline, unheated tests Delayed heating with initiation when the fuel reaches a prescribed low temperature limit, showed promise of being more efficient than continuous heating Regardless of the mode or rate of heating, complete flowability (zero holdup) could not be restored by fuel heating The severe, extreme-day environment imposed by the test caused a very small amount of subfreezing fuel to be retained near the tank surfaces even at high rates of heating Correlations of flowability established for unheated fuel tests also could be applied to the heated test results if based on boundary-layer temperature or a solid index (subfreezing point) characteristic of the fuel Previously announced in STAR as N82-26483

Heating experiments for flowability improvement of near-freezing aviation fuel

The impact that the supply, quality, and processing costs of future fuels may have on aircraft technology is assessed. The potential range of properties for future jet fuels is discussed along with the establishment of a data base of fuel property effects on propulsion system components. Also, the evolution and evaluation of advanced component technology that would permit the use of broader property fuels and the identification of technical and economic trade-offs within the overall fuel production-air transportation system associated with variations in fuel properties are examined.

/pdf/the-impact-of-fuels-on-aircraft-technology-through-the-year-4gvta87zle.pdf

The impact of fuels on aircraft technology through the year 2000

The Aircraft Energy Efficiency (ACEE) Program was established by NASA to improve the fuel efficiency of commercial transport aircraft and thereby to reduce the amount of fuel consumed by the air transportation industry. One of the final items developed by the program is an improved fairing which is the aft closure for the thrust reverser actuators on the JT8D nacelles on DC-9 aircraft. The reduced-drag fairing uses, in the interest of weight savings, an advanced composite construction. The composite material contains Kevlar 49 fibers in a PMR-15 matrix. Attention is given to the aerodynamic configuration, the material system, and aspects of fabrication development.

Kevlar/PMR-15 polyimide matrix composite for a complex shaped DC-9 drag reduction fairing

Improving fuel efficiency, new sources of jet fuel, and noise and emission control are subjects of NASA's aeronautics program. Projects aimed at attaining a 5% fuel savings for existing engines and a 13-22% savings for the next generation of turbofan engines using advanced components, and establishing a basis for turboprop-powered commercial air transports with 30-40% savings over conventional turbofan aircraft at comparable speeds and altitudes, are discussed. Fuel sources are considered in terms of reduced hydrogen and higher aromatic contents and resultant higher liner temperatures, and attention is given to lean burning, improved fuel atomization, higher freezing-point fuel, and deriving jet fuel from shale oil or coal. Noise sources including the fan, turbine, combustion process, and flow over internal struts, and attenuation using acoustic treatment, are discussed, while near-term reduction of polluting gaseous emissions at both low and high power, and far-term defining of the minimum gaseous-pollutant levels possible from turbine engines are also under study.

J. S. Grobman

Papers

Preparing aircraft propulsion for a new era in energy and the environment