Challenges of future aircraft propulsion: A review of distributed propulsion technology and its potential application for the all electric commercial aircraft

https://www.repository.cam.ac.uk/bitstream/handle/1810/245229/futureACtechAAM.pdf?sequence=1

The potential of future aircraft technology for noise and pollutant emissions reduction

Consideration of the environmental impact of aircraft has become critical in commercial aviation. The continued growth of air traffic has caused increasing demands to reduce aircraft emissions, imposing new constraints on the design and development of future airplane concepts. In this paper, an aircraft design optimisation framework is used to design aircraft that minimise specific environmental metrics. Multidisciplinary design optimisation is used to optimise aircraft by simultaneously considering airframe, engine and mission. The environmental metrics considered in this investigation are CO2 emissions — which are proportional to fuel burn — and landing-takeoff NOx emissions. The results are compared to those of an aircraft with minimum direct operating cost. The design variables considered in the optimisation problems include aircraft geometry, engine parameters, and cruise settings. An augmented Lagrangian particle swarm optimiser and a genetic algorithm are used to solve the single objective and multi-objective optimisation problems, respectively.

Aircraft conceptual design for optimal environmental performance

This paper presents the Multidisciplinary Integrated Conceptual Aircraft Design and Optimization (MICADO) environment that has been developed during the last years at the Institute of Aeronautics and Astronautics (ILR) of RWTH Aachen University. The MICADO environment allows for automated aircraft design and assessment with a minimum of user input, i.e. a set of top-level requirements and specications. The homogeneous software environment allows for fast parameter studies and optimizations in a wide parameter space and with low computational eort. Due to the integrated design and assessment approach, variations of top-level requirements, local parameter changes as well as integration of new technologies or systems are captured into overall aircraft evaluation parameters such as block fuel or costs. The MICADO software architecture in terms of control and data ow, program structure and parameterization principles is presented. Further, the aircraft design and assessment methodology including the underlying models are discussed, as well as applications of MICADO for aircraft design studies and operational studies. Finally, functionalities and strengths of the proposed methodology are demonstrated by a case study, in which MICADO is used for the design and optimization of a conventional short-range aircraft. For the designed aircraft, variations of initial sizing parameters as well of Mach number and wing sweep angle are performed and overall aircraft design results are discussed.

An Integrated Environment for Preliminary Aircraft Design and Optimization

This paper presents a review, classification schemes, critique, a simple meta-analysis and future research implication of fuel consumption optimization (FCO) literature in the air transport sector. This review is based on 277 articles published in various publication outlets between 1973 and 2014. A review of 277 articles related to the FCO in air transport was carried out. It provides an academic database of literature between the periods of 1973– 2014 covering 69 journals and proposes a classification scheme to classify the articles. Twelve hundred of articles were identified and reviewed for their direct relevance to the FCO in air transport. Two hundred seventy seven articles were subsequently selected, reviewed and classified. Each of the 277 selected articles was categorized on four FCO dimensions (Aircraft technology & design, aviation operations & infrastructure, socioeconomic & policy measures, and alternate fuels & fuel properties). The articles were further classified into six categories of FCO research methodologies (analytical - conceptual, mathematical, statistical, and empirical- experimental, statistical, and case studies) and optimization techniques (linear programming, mixed integer programming, dynamic programming, gradient based algorithms, simulation modeling, and nature based algorithms). In addition, a simple meta-analysis was also carried out to enhance understanding of the development and evolution of research in the FCO. This has resulted in the identification of 277 articles from 69 journals by year of publication, journal, and topic area based on the two classification schemes related to FCO research, published between, 1973 to December- 2014. In addition, the study has identified the 4 dimensions and 98 decision variables affecting the fuel consumption. Also, this study has explained the six categories of FCO research methodologies (analytical - conceptual, mathematical, statistical, and empirical-experimental, statistical, and case studies) and optimization techniques (linear programming, mixed integer programming, dynamic programming, gradient based algorithms, simulation modeling, and nature based algorithms). The findings of this study indicate that the analytical-mathematical research methodologies represent the 47 % of FCO research. The results show that there is an increasing trend in research of the FCO. It is observed that the number of published articles between the period 1973 and 2000 is less (90 articles), so we can say that there are 187 articles which appeared in various journals and other publication sources in the area of FCO since 2000. Furthermore there is increased trend in research on FCO from 2000 onward. This is due to the fact that continuously new researchers are commencing their research activities in FCO research. This shows clearly that FCO research is a current research area among many research groups across the world. Lastly, the prices of jet fuel have significantly increased since the 2005. The aviation sector’s fuel efficiency improvements have slowed down since the 1970s–1980s due to the slower pace of technological development in engine and aerodynamic designs and airframe materials. We conclude that FCO models need to address the composite fuel consumption problem by extending models to include all the dimensions, i.e. aircraft technology & design, aviation operations & infrastructure, socioeconomic & policy measures, and alternative fuels & fuel properties. FCO models typically comprise all the four dimensions and this reality need to be taken into account in global FCO models. In addition, these models should have objectives or constraints to evaluate the aircraft sizes according to market structure, impact of various policy measures on fuel burn, and near term potential alternative fuel options in the global FCO problem. In the models reviewed, we evaluated that, only the few authors considered these factors. The literature identifies 98 decision variables affecting the fuel consumption related to various dimensions in air transport. So we can conclude that this analysis could represent the informational framework for FCO research in air transport. Our analysis provides a roadmap to guide future research and facilitate knowledge accumulation and creation concerning the application of optimization techniques in fuel consumption of air transport. The addressed dimensions & decision variables could be of potential value to future researchers on the aviation fuel consumption optimization research and is also capable of further refinements. In future, for fuel consumption optimization the explored decision variables could be checked for their reliability and validity and a statistically significant model with minimum number of decision variable could be developed. Further, on the basis of this statistical significant model and with the best market requirement for transport aircraft, the researchers can frame the objective function for fuel consumption minimization problem & decide their dependent variables, independent variables, constant, and constraints. Furthermore, this study will also provide the base for fuel conservation, energy efficiency, and emission reduction in the aviation sector.

/pdf/fuel-consumption-optimization-in-air-transport-a-review-1ok1bqkivd.pdf

Fuel consumption optimization in air transport: a review, classification, critique, simple meta-analysis, and future research implications

Commercial aircraft operations impact the atmosphere through emissions of greenhouse gases and greenhouse gas precursors and through the formation of contrails and cirrus clouds. Aircraft are attributed with emitting approximately 2% of all anthropogenic carbon dioxide (CO2), and the total radiative forcing caused by aircraft emissions is a factor of two to four times greater than radiative forcing due to aircraft CO2 emissions alone [IPCC 1999]. Non-CO2 radiative forcing results primarily from emissions of oxides of nitrogen (NOx) and the formation of contrails and cirrus clouds. The magnitudes of climate impacts due to both of these phenomena depend strongly on cruise altitude. Additionally, aircraft fuel burn and NOx emissions rate depend on ight altitude. This study combines altitude variation of fuel consumption, emissions rate, and emissions eects to examine the relative climate impacts of dierent aircraft designs, as measured by the global mean temperature change resulting from 100 years of sustained aircraft operation. A simple time- and altitudevarying climate model is presented and integrated with an aircraft conceptual design code. Optimization studies are performed to compare economic and environmental performance of aircraft congurations. First, we optimize for a minimum-cost conguration, which is used as a reference for comparing performance of a variety of green designs. By optimizing an aircraft for minimum fuel burn or minimum NOx emissions, savings of up to 16% in fuel burn and 50% in NOx emissions are possible compared with a minimum-cost design. However, these aircraft achieve small reductions in global warming impacts of at most 7%. More signicant reductions in global warming impacts can be attained by designing aircraft to y at lower altitudes. A 30% reduction in global warming impacts can be reached by designing aircraft to cruise at about 28,000 ft and Mach 0.75, which increases operating costs by 1 to 2% relative to a minimum cost aircraft. A 50% reduction in global warming impacts can be achieved by aircraft designed to cruise at 25,000 ft and Mach 0.72, with a 1.5 to 3% increase in total operating costs. Up to a 75% reduction in global warming impacts can be attained by designing aircraft to cruise as low as 18,000 ft. Unfortunately, there is considerable uncertainty in estimating the global warming eects of NO x emissions and cloud formation. To address this, studies are performed to examine the sensitivity of results to variation in the magnitude of radiative forcing due to NOx emissions and cloud formation. Regardless of whether these forcings are much greater or less than current best estimates, there is still a potential net global warming impact savings of 20 to 55% possible by designing aircraft to cruise 10,000 ft lower and at a 12% lower Mach number than the minimum-cost conguration.

http://adl.stanford.edu/aa260/Lecture_Notes_files/asm2009slides.pdf

Aircraft Design: Trading Cost and Climate Impact

The Silent Aircraft Initiative produced an aircraft design that combined many new and novel technologies to give a solution that was predicted to be fuel-efficient as well as extremely quiet. The study presented in this paper seeks to assess the benefits and penalties of each of the proposed technologies. A method has been developed that estimates the overall change in fuel consumption and engine noise caused by modifications to an aircraft design. The method sizes a propulsion system for a specified design and determines adjustments to the cruise performance based on changes in the engine components, the installation system, and system weight. The offdesign performance is also calculated so that the noise can be estimated. The method has been applied to show what contribution each silent aircraft technology made to the overall goal of the project. It also shows the tradeoffs between noise and fuel consumption for various technologies and indicates that there are configurations that can achieve both lower fuel burn and lower engine noise. The method has been used to identify a low-risk configuration of the silent aircraft, for which a new design is presented.

/pdf/assessment-of-technologies-for-the-silent-aircraft-odx3ryi209.pdf

Assessment of Technologies for the Silent Aircraft Initiative

Assessment of Future Aircraft Technologies on Engine Noise and Fuel Consumption


 In this paper, a life cycle cost-based optimization analysis is carried out to compare the energy and cost performance of diverse sustainable designs of a residential building. These designs include code optimal, net zero energy building, and passive house. It is found that in the case where natural gas is employed, a total energy savings of 77% is optimal. The cost optimal design for electrification achieves 100.12% of energy savings relative to the baseline design but results slightly high life cycle cost than that of the gas cost optimal design. In addition, the results indicate that due to the additional capital costs for the required energy efficient measures, the passive house case is less economically optimal than NZEB design options. Overall, the most cost-optimal designs are found to be for natural gas heated homes with marginally better energy performance than the applicable currently energy efficiency code with 10 kW solar panels.

Emily Schwartz

Papers

Aircraft Design: Trading Cost and Climate Impact

Assessment of Technologies for the Silent Aircraft Initiative

Assessment of Future Aircraft Technologies on Engine Noise and Fuel Consumption

Comparative Analysis Optimal Designs for Passive, Electrified, and Net Zero Energy Residential Buildings