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1.	Grönstedt, Tomas, 1970, et al. (author) Low Pressure System Component Advancements and Its Influence on Future Turbofan Engine Emissions 2009 In: Proceedings of ASME Turbo Expo 2009: Power for Land, Sea and Air, GT2009. Conference paper (peer-reviewed)abstract Within the European research project EnVIronmenTALly Friendly Aero Engines, VITAL, a number of low pressure system component technologies are being investigated. The emerging progress will allow the design of new power plants providing a step change in engine fuel burn and noise. As part of the VITAL project a Technoeconomic and Environmental Risk Assessment tool, the TERA2020, is being developed. Within this tool, means to assess the impact of component technology progress on the engine/aircraft system level has been implemented. Sensitivities relating parameters traditionally used to describe component performance, such as allowable shaft torque, low pressure turbine stage loading, fan blade weight and system level parameters have been established. This allows a direct assessment of the impact of component research progress on the VITAL power plant CO2 and noise emissions.
2.	Abdalla, Alvaro, et al. (author) The Effect of Engine Dimensions on Supersonic Aircraft Performance 2013 In: 4:th CEAS Air & Space Conference. Conference paper (peer-reviewed)abstract In aircraft design a critical part of the design isthe engine selection. This is typically making aselection from exiting engines. Looking at a nextgeneration future fighters, however, where thetime of deployment may be 20-30 years in thefuture this is not a valid approach as there willbe an evolution in the engine designs. E.g. anew European fighter aircraft will most likelybe a collaborative project also involving thedevelopment of an engine for that aircraft. Inthis study conceptual engine-airframe co-designis demonstrated, using models of comparablefidelity for both the engine design and theaircraft design. This co-design leads to a deeperunderstanding of the tradeoffs from both sides,and means that also more radical designs andinnovations can be evaluated in a fair way.
3.	Abedi, Hamidreza, 1979, et al. (author) Preliminary Analysis of Compression System Integrated Heat Management Concepts Using LH 2 -Based Parametric Gas Turbine Model 2022 In: Aerospace. - : MDPI AG. - 2226-4310. ; 9:4 Journal article (peer-reviewed)abstract The investigation of the various heat management concepts using LH2 requires the development of a modeling environment coupling the cryogenic hydrogen fuel system with turbofan performance. This paper presents a numerical framework to model hydrogen-fueled gas turbine engines with a dedicated heat-management system, complemented by an introductory analysis of the impact of using LH2 to precool and intercool in the compression system. The propulsion installations comprise Brayton cycle-based turbofans and first assessments are made on how to use the hydrogen as a heat sink integrated into the compression system. Conceptual tubular compact heat exchanger designs are explored to either precool or intercool the compression system and preheat the fuel to improve the installed performance of the propulsion cycles. The precooler and the intercooler show up to 0.3% improved specific fuel consumption for heat exchanger effectiveness in the range 0.5–0.6, but higher effectiveness designs incur disproportionately higher pressure losses that cancel-out the benefits.
4.	Ali, Fakhre, 1986, et al. (author) A Noise Assessment framework for Subsonic Aircraft and Engines 2016 In: ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition, GT 2016; Seoul; South Korea. - 9780791849682 ; vol 1 Conference paper (peer-reviewed)abstract This paper proposes a preliminary subsonic aircraft and engine noise assessment framework, capable of computing the aircraft total noise level at all three certification points (i.e. Approach, Lateral, and Flyover) defined by the International Civil Aviation Organisation. The proposed framework is numerically integrated to account for the complete aircraft noise sources (i.e. the fuselage, wings, landing gear, as well as noise sources resulting from the engine component level, (i.e. fan, compressor, combustor, turbine, and jet). The developed framework is based on a wide-range of empirical and semi-empirical correlations collected from the public domain literature. The fidelity of the framework also caters for flight effects such as atmospheric attenuation, spherical spreading, Doppler shift, lateral attenuation, retarded time and ground reflection. A conversion between the sound pressure level SPL [SPLdB] to effective perceived noise level EPNL [EPNdB] is also included to allow for a consistent comparison with the certification procedure.Through the successful deployment of the proposed framework a generic aircraft model, representative of a modern commercial carrier aircraft has been investigated, operating under representative operational conditions. The sound pressure level corresponding to various aircraft and engine component have been thoroughly investigated and verified with trends acquired based on the theory. Furthermore, the predictions made by theframework corresponding to the aforementioned threecertification points have also been verified against the noise level measurements provided by the International Civil Aviation Organization. The results acquired exhibit good correlation against the verification data for total noise levels at the microphones. Furthermore, a component level comparison is also presented which exhibit good agreement with verification data. The deployed methodology can essentially be regarded asan enabling technology to support the effective and efficient implementation of framework(s) (i.e. Technoeconomic, Environmental and Risk Assessment) targeted to evaluate the existing and advanced aircraft and engine architectures in terms of operational performance and environmental impact.
5.	Ander, Mats, 1964, et al. (author) Development, accomplishment and evaluation of a project course in applied mechanics---Lessons learnt 2009 In: Svenska mekanikdagarna, Södertälje 2009, 15-17-juni, Session 7:4-Utbildning, sid 99 (1 page abstract). ; , s. 99- Conference paper (other academic/artistic)abstract Development, accomplishment and evaluation of a project course in applied mechanics---Lessons learnt M. Ander , T. Grönstedt, T. Abrahamsson and G. JohanssonThis presentation concerns teaching and learning from working in projects within the Chalmers Master programme in Solid and fluid mechanics. The academic tradition requires teaching solid and fluid mechanics as separated subjects of applied mechanics. The researchers/teachers and students belonging to either discipline do not meet on daily basis and thus two separate cultures develop; CFD for fluids and FEM for solids.However, in industry today fresh engineers will meet challenges in multidisciplinary problems and they are expected to be able to know how to treat them. As a remedy to better prepare for their engineering profession, a project course in applied mechanics has been developed. The outline of the course follows the CDIO[1] learning approach: Conceive, Design, Implement and Operate. Starting off from back of the envelope calculations, where all students are required to address all disciplines, the project proceeds towards distinct specializations. The students, divided into groups of six to seven members, focus on ‘student specialists’ roles in solid/structural mechanics-FEM, fluid dynamics, and experimental modal analysis EMA, simulating a true multidisciplinary working environment. The projects studied incorporate a fluid structure interaction core problem, but are required to pose challenges within each specialisation. The task is formulated as a competition to find better solutions or as an investigation of existing methods to solve a problem at hand. The examination is based on individual assignments, group work, presentation of a final report and opposition. As resources for analysing the problems, the students have access to wind tunnel testing, EMA-equipment, computer rooms with commercial software for CFD and FEM. This year we have introduced the ANSYS workbench as a common platform for fluid–structure interaction simulations, allowing the teams to work more closely together. The student perspective is dominated by the urge to approach real world problems with industrial tools. A better contact and understanding between students as well as between teachers/researchers in the different disciplines of applied mechanics are achieved by this approach. Some outstanding challenges are the limited time frame of the course, the time consuming communication required within the teachers team and the student frustration arising from having to address open end problems. [1]www.cdio.org
6.	Andersson, Josefin, 1994, et al. (author) Propulsion Installation Modelling for geared Ultra-high bypass ratio engine cycle design 2020 Conference paper (other academic/artistic)abstract About 3% of the greenhouse gas emissions in the EU are derived from aviation. By 2020, the global international aviation emissions are assumed to be approximately 70% higher than those in 2005 and a strong continued growth in travel demand is expected at least up until 2035. A radical reduction of emissions have to occur on multiple fronts ranging from incremental improvements of advanced propulsion systems to new fuels and electrification. The desire to get higher efficiencies has contributed to the movement from turbojet engines to today's high bypass ratio turbofan engines. The fuel consumption and propulsive efficiency of turbofan engines are highly dependent on the fan pressure ratio (FPR). Decreasing FPR gives an improved fuel and propulsive efficiency as long as installation losses do not exceed potential benefits. As part of the Clean Sky project IVANHOE, new types of nacelles will be developed to enable installation of propulsion systems with radically increased bypass ratio and reduced FPR. In this work the process of describing and selecting a suitable propulsion system is described. The cycle is defined by a multidisciplinary analysis considering nacelle drag, propulsion system weight and engine performance. Effects of variation in turbine cooling with cycle change and small size turbomachinery efficiency is considered defining the core size and pressure ratio. Variations in installed SFC with fan diameter choice is quantified along a suboptimal line of fan pressure ratio and bypass ratio for a specific optimal overall pressure ratio. The final cycle choice is presented.
7.	Assato, Marcelo, et al. (author) PERFORMANCE BENEFITS OF A FAN ON BLADE – FLADE – FOR A VARIABLE CYCLE ENGINE 2022 In: 33th Congress of the International Council of the Aeronautical Sciences. - 2958-4647. - 9781713871163 - 9781713871163 ; 7, s. 4888-4902 Conference paper (peer-reviewed)abstract Variable cycle engines promise to enable adaptive cycles that give close to optimal performance over a wide range of conflicting mission requirements, such as low altitude high speed flight and supercruise still providing excellent range. Modelling such engines pose challenges for general purpose software since variable geometry gas paths modify the underlying set of equations being solved. It is possible to use multiple engine models transferring design data between the models. This, however, creates a high risk for inconsistency and modelling error. It is more attractive if the solutions obtained could be determined using the same model. In this work an in-house software was developed to model an Adaptive Cycle Engine (ACE). This development was used to show how variable cycle mode switches can be integrated into general purpose performance tools. The variable cycle engine uses a FLADE, which is a "fan on blade" component, to extend its range and to provide improved subsonic performance. The individual impact of the components, its effect on propulsion performance parameters and in the engine installation were analyzed as the main results. The contribution from this paper is thus two-fold, firstly the paper goes ahead and proposes new methods for the simulation of mode switching in generic performance tools by introducing dynamic equation systems. Secondly, the paper then studies the FLADE component and its potential performance benefits if added to a conventional turbofan architecture.
8.	Avellan, Rickard, 1976, et al. (author) AN ASSESSMAn assessment of a turbofan engine using catalytic interturbine combustionENT OF A TURBOFAN ENGINE USING CATALYTIC INTERTURBINE COMBUSTION 2009 In: 2009 ASME Turbo Expo; Orlando, FL; United States; 8 June 2009 through 12 June 2009. - 9780791848852 ; 2009:GT2009-59950, s. 383-392 Conference paper (peer-reviewed)abstract The potential for using catalytic combustion in aero engines is discussed. Some preliminaries relating to NOx formation and material capabilities are analyzed. Various means to integrate catalytic combustors in aero engines are described. In particular, catalytic interturbine combustion is investigated both in terms of technical feasibility and through a preliminary design exercise. A thermodynamic design point study is presented analyzing a configuration with a combustor located concentrically around the engine core receiving pressurized air through an interstage high pressure compressor bleed. A parameter study of the compressor bleed ratio is presented for the configuration. A substantial reduction in NOx emissions at the expense of an increase in mission fuel consumption is observed.
9.	Avellan, Rickard, 1976, et al. (author) Preparing for Proof-of-concept of a Novel Propeller for Open Rotor Engines 2015 In: ISABE-2015-20097. Conference paper (peer-reviewed)abstract This article describes the development of a novel high-speed propeller concept. Large-scale propeller tests are extremely expensive and thus not appropriate at early R&D development phases. A convenient approach is to use computational methods validated by small-scale tests with propellers manufactured from low-cost materials and rapid manufacturing methods. The present paper is describing this cross validation work explaining differences between numerics and experiments. Preferred materials and manufacturing methods for high-speed future wind tunnel tests are discussed. We also discuss the progress of development of the aerodynamic design of the concept propeller.
10.	Camilleri, William, et al. (author) Concept description and assessment of the main features of a geared intercooled reversed flow core engine 2015 In: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering. - : SAGE Publications. - 0954-4100 .- 2041-3025. ; 229:9, s. 1631-1639 Journal article (peer-reviewed)abstract Intercooled turbofan cycles allow higher overall pressure ratios to be reached which gives rise to improved thermal efficiency. Intercooling also allows core mass flow rate to be reduced which facilitates higher bypass ratios. A new intercooled core concept is proposed in this paper which promises to alleviate limitations identified with previous intercooled turbofan designs. Specifically, these limitations are related to core losses at high overall pressure ratios as well as difficulties with the installation of the intercooler. The main features of the geared intercooled reversed flow core engine are described. These include an intercooled core, a rear-mounted high-pressure spool fitted rearwards of the low-pressure spool as opposed to concentrically as well as a mixed exhaust. In these studies, the geared intercooled reversed flow core engine has been compared with a geared intercooled straight flow core engine with a more conventional core layout. This paper compares the mechanical design of the high-pressure spools and shows how different high-pressure compressor and high-pressure turbine blade heights can affect over-tip leakage losses. In the reversed configuration, the reduction in high-pressure spool mean diameter allows for taller high-pressure compressor and turbine blades to be adopted which reduces over-tip leakage losses. The implication of intercooler sizing and configuration, including the impact of different matrix dimensions, is assessed for the reversed configuration. It was found that a 1-pass intercooler would be more compact although a 2-pass would be less challenging to manufacture. The mixer performance of the reversed configuration was evaluated at different levels of mixing effectiveness. This paper shows that the optimum ratio of total pressure in the mixing plane for the reversed flow core configuration is about 1.02 for a mixing effectiveness of 80%. Lower mixing effectiveness would result in a higher optimum ratio of total pressure in the mixing plane and fan pressure ratio.
11.	Capitao Patrao, Alexandre, 1988, et al. (author) Aerodynamic and aeroacoustic comparison of optimized high-speed propeller blades 2018 In: 2018 Joint Propulsion Conference. - Reston, Virginia : American Institute of Aeronautics and Astronautics. Conference paper (peer-reviewed)abstract The Boxprop is a high-speed propeller concept intended for aircraft engines, which features blade pairs connected at the tip in order to decrease tip vortex strength, possibly reducing noise and improving aerodynamic performance relative to conventional high-speed propellers. This paper investigates the aerodynamic and aeroacoustic performance of three aerodynamically optimized high speed propellers; a 6-bladed conventional propeller, a 12-bladed conventional propeller, and a 6-bladed Boxprop. Performance results will be be compared for the three designs, with a focus on sectional performance and wake flow characteristics, and will show that the 6-bladed Boxprop performance lies somewhat in-between its 6 and 12-bladed conventional counterparts. The noise level at various observer positions is presented, and shows that the noise roughly follows the values of efficiency for the three propellers, with the Boxprop noise level being higher than the 12-bladed conventional propeller, but lower than the 6-bladed one. The lower blade loading and higher efficiency of the Boxprop relative to the 6-bladed conventional propeller results in slightly lower levels of noise at cruise.
12.	Capitao Patrao, Alexandre, 1988, et al. (author) An Optimization Platform for High Speed Propellers 2016 Conference paper (other academic/artistic)abstract To improve the efficiency by which current power plants translate jet energy into useful thrust the use of turboprop and in particular open rotor aircraft are being revisited. One challenge in association with developing new powerplants for such aircraft is high speed propeller design in general and noise prediction in particular.The Boxprop was invented in 2009 by GKN Aerospace in order to mitigate the effects of the tip vortex on noise and to improve upon the aerodynamics of a conventional propeller blade. The Boxprop is composed of a double-bladed propeller joined at the tips, and the design has the potential to eliminate the tip vortex, and thereby decrease that particular noise source. The complex and highly three-dimensional shape of an advanced propeller blade is challenging to model with classical propeller design methods, requiring instead more sophisticated optimization methods.This paper presents an optimization platform developed for high speed propellers, and illustrates its use by performing a reduced aerodynamic optimization of the Boxprop. The optimization process starts by performing a Latin Hypercube Sampling of the design space, and analyzes the resulting geometries using CFD. A meta-model employing radial basis functions is then used to interpolate on the obtained CFD results, which the GA uses to find optimal candidates along the obtained Pareto front. These designs are then evaluated using CFD, and their data added to the meta-model. The process iterates until the meta-model converges.The results of this paper demonstrate the capability of the presented optimization platform, and applying it on the Boxprop has resulted in valuable design improvements and insights. The obtained designs show less blade interference, more efficiently loaded blades, and less produced swirl. The methodology for geometry generation, meshing and optimizing is fast, robust, and readily extendable to other types of optimization problems, and paves the way for future collaborative research in the area of turbomachinery.
13.	Capitao Patrao, Alexandre, 1988, et al. (author) Compact heat exchangers for hydrogen-fueled aero engine intercooling and recuperation 2024 In: Applied Thermal Engineering. - 1359-4311. ; 243 Journal article (peer-reviewed)abstract This study investigates the application of compact heat exchangers for the purpose of intercooling and recuperation systems for short-to-medium range aircraft equipped with hydrogen-fueled turbofan engines. The primary objective is to assess the potential effects of engine-integrated compact heat exchangers on fuel consumption and emissions. The paper encompasses the conceptual design of integrated heat exchangers and associated ducts, followed by aerodynamic optimization studies to identify suitable designs that minimize air-side pressure losses and ensure flow uniformity at the inlet of the high-pressure compressor. Pressure drop correlations are then established for selected duct designs and incorporated into a system-level performance model, allowing for a comparison of their impact on specific fuel consumption, NOx emissions, and fuel burn against an uncooled baseline engine. The intercooled-recuperated engine resulted in the most significant improvement in take-off specific fuel consumption, with a reduction of up to 7.7% compared to the baseline uncooled engine, whereas the best intercooled engine resulted in an improvement of about 4%. Furthermore, the best configuration demonstrated a decrease in NOx emissions by up to 37% at take-off and a reduction in mission fuel burn by 5.5%. These enhancements were attributed to reduced compression work, pre-heating of the hydrogen fuel, and lower high-pressure compressor outlet temperatures.
14.	Capitao Patrao, Alexandre, 1988, et al. (author) The heat transfer potential of compressor vanes on a hydrogen fueled turbofan engine 2024 In: Applied Thermal Engineering. - 1359-4311. ; 236 Journal article (peer-reviewed)abstract Hydrogen is a promising fuel for future aviation due to its CO2-free combustion. In addition, its excellent cooling properties as it is heated from cryogenic conditions to the appropriate combustion temperatures provides a multitude of opportunities. This paper investigates the heat transfer potential of stator surfaces in a modern high-speed low-pressure compressor by incorporating cooling channels within the stator vane surfaces, where hydrogen is allowed to flow and cool the engine core air. Computational Fluid Dynamics simulations were carried out to assess the aerothermal performance of this cooled compressor and were compared to heat transfer correlations. A core air temperature drop of 9.5 K was observed for this cooling channel design while being relatively insensitive to the thermal conductivity of the vane and cooling channel wall thickness. The thermal resistance was dominated by the air-side convective heat transfer, and more surface area on the air-side would therefore be required in order to increase overall heat flow. While good agreement with established heat transfer correlations was found for both turbulent and transitional flow, the correlation for the transitional case yielded decent accuracy only as long as the flow remains attached, and while transition was dominated by the bypass mode. A system level analysis, indicated a limited but favorable impact at engine performance level, amounting to a specific fuel consumption improvement of up to 0.8 % in cruise and an estimated reduction of 3.6 % in cruise NOx. The results clearly show that, although it is possible to achieve high heat transfer rate per unit area in compressor vanes, the impact on cycle performance is constrained by the limited available wetted area in the low-pressure compressor.
15.	Capitao Patrao, Alexandre, 1988, et al. (author) Wake Analysis of an Aerodynamically Optimized Boxprop High Speed Propeller 2019 In: Journal of Turbomachinery. - : ASME International. - 1528-8900 .- 0889-504X. ; 141:9 Journal article (peer-reviewed)abstract The Boxprop is a novel, double-bladed, tip-joined propeller for high-speed flight. The concept draws inspiration from the box wing concept and could potentially decrease tip vortex strength compared with conventional propeller blades. Early Boxprop designs experienced significant amounts of blade interference. By performing a wake analysis and quantifying the various losses of the flow, it could be seen that these Boxprop designs produced 45% more swirl than a conventional reference blade. The reason for this was the proximity of the Boxprop blade halves to each other, which prevented the Boxprop from achieving the required aerodynamic loading on the outer parts of the blade. This paper presents an aerodynamic optimization of a 6-bladed Boxprop aiming at maximizing efficiency and thrust at cruise. A geometric parametrization has been adopted which decreases interference by allowing the blade halves to be swept in opposite directions. Compared with an earlier equal-thrust Boxprop design, the optimized design features a 7% percentage point increase in propeller efficiency and a lower amount of swirl and entropy generation. A vortex-like structure has also appeared downstream of the optimized Boxprop, but with two key differences relative to conventional propellers. (1) Its formation differs from a traditional tip vortex and (2) it is 46% weaker than the tip vortex of an optimized 12-bladed conventional propeller.
16.	Capitao Patrao, Alexandre, 1988, et al. (author) Wake and Loss Analysis for a Double Bladed Swept Propeller 2016 In: Proceedings of ASME Turbo Expo 2016: Turbine Technical Conference and Exposition, Seoul, South Korea, Jun 13-17, 2016. ; 1 Conference paper (peer-reviewed)abstract Inspired by Prandtl’s theory on aircraft wings with minimum induced drag, the authors introduced a double-bladed propeller, the Boxprop, intended for high-speed flight. The basic idea is to join the propeller blades pair-wise at the tip to improve aerodynamics and mechanical properties compared to the conventional propeller. The rather complex geometry of the double blades gives rise to new questions, particularlyregarding the aerodynamics.This paper presents a propeller wake energy analysis method which gives a better understanding of the potential performance benefits of the Boxprop and a means to improve its design.CFD analysis of a five bladed Boxprop demonstrated its ability to generate typical levels of cruise thrust at a flight speed of Mach 0.75. The present work shows that the near tip velocity variations in the wake are weaker for this propeller than a conventional one, which is an indication that a counter rotatingpropeller designed with a Boxprop employed at the front may exhibit lower interaction noise.
17.	Capitao Patrao, Alexandre, 1988, et al. (author) Wake Energy Analysis Method Applied to the Boxprop Propeller Concept 2018 In: Aerospace Science and Technology. - : Elsevier BV. - 1270-9638. ; 79, s. 689-700 Journal article (peer-reviewed)abstract Inspired by Prandtl's theory on aircraft wings with minimum induced drag, the authors have introduced a double-bladed propeller, the Boxprop, intended for high-speed flight. The basic idea is to join the propeller blades pairwise at the tip to decrease tip vortex strength and improve mechanical properties compared to a conventional propeller. The present work develops a wake analysis method allowing an energy breakdown of the flow as well as making the irreversibility of the flow explicit by using the entropy lost work concept. The method quantifies the strength of flow features such as tip vortices and wakes in terms of engine power. In contrast to existing work, this method removes assumptions of uniform flow, no radial flow, and constant static pressure in the propeller jet. The results of the wake analysis method can be summarized into three key findings 1) the energy in the tip-vortex of the Boxprop design is comparatively speaking non-existent, 2) the swirl energy level of the Boxprop is higher and this turbomachine is thus more in need of a downstream counter-rotating blade to recover the energy, 3) the Boxprop develops a much larger part of its thrust closer to the hub. Analysis of this aspect of the flow reveals that blade interference approaching the tip, where the blades in a pair are more closely spaced, is quite pronounced. In turn, this indicates that maximum efficiency Boxprop designs are more likely to be obtained by having larger axial separation of the two blades.
18.	Costa, Fabíola Paula, et al. (author) Aerodynamic Analysis of Conventional and Boundary Layer Ingesting Propellers 2023 In: Journal of Engineering for Gas Turbines and Power. - : ASME International. - 1528-8919 .- 0742-4795. ; 145:1 Journal article (peer-reviewed)abstract The boundary layer ingestion (BLI) concept has emerged as a novel technology for reducing aircraft fuel consumption. Several studies designed BLI-fans for aircraft. BLI-propellers, although, have still received little attention, and the choice of open-rotors or ducted propellers is still an open question regarding the best performance. The blade design is also challenging because the BLI-propulsors ingest a nonuniform flow. These aspects emphasize further investigation of unducted and ducted BLI-propulsors and the use of optimization frameworks, coupled with computational fluid dynamics simulations, to design the propeller to adapt to the incoming flow. This paper uses a multi-objective NSGA-II optimization framework, coupled with three-dimensional RANS simulations and radial basis function (RBF) metamodeling, used for the design and optimization of three propeller configurations at cruise conditions: (a) conventional propeller operating in the freestream, (b) unducted BLI-propeller, and (c) ducted BLI-propeller, both ingesting the airframe boundary layer. The optimization results showed a significant increase in chord and a decrease in the blade angles in the BLI configurations, emphasizing that these geometric parameters optimization highly affects the BLI-blade design. The unducted BLI-propeller needs approximately 40% less shaft power than the conventional propeller to generate the same amount of propeller force. The ducted BLI-propeller needs even less power, 47%. The duct contributes to the tip vortex weakening, recovering the swirl, and turning into propeller force, as noticed from 80% of the blade span to the tip. However, the unducted and ducted BLI-configurations presented a higher backward force, 26% and 46%, respectively, compared to the conventional propeller, which can be detrimental and narrow the use of these configurations.
19.	Da Silva, Lucilene Moraes, et al. (author) Numerical investigation of film and impingement cooling schemes for gas turbine application 2018 In: Proceedings of the ASME Turbo Expo. ; 5A-2018 Conference paper (peer-reviewed)abstract In modern gas turbine engines, many sophisticated cooling schemes are used to maintain the turbine blade temperature in acceptable levels. These schemes, such as convective cooling, film cooling, impingement cooling and the use of pin fins, can be combined to increase the cooling effectiveness. Jet impingement cooling, pin fins and convective cooling are internal cooling techniques, in which the cooling is achieved based on coolant flow through internal blade channels decreasing the blade metal temperature. Film cooling is an external cooling technique, in which the cold fluid (air) is injected into the hot gas flow through discrete holes providing a coolant film at blade surface, protecting the blade metal. In this way, the present work refers to the numerical investigation of internal and external cooling strategies applied in gas turbines. The methodology developed to analyze such strategies is based on the flat-plate approach with laboratory length scales and Computational Fluid Dynamics (CFD) techniques, being the flow, in the study domain, considered viscous, turbulent and compressible. A commercial CFD program is used to solve the general equations of fluid mechanics with Reynolds Average Navier-Stokes (RANS) technique for steady state regime and Shear Stress Transport (SST) turbulence model to determine the flow eddy viscosity. The combined effects of internal and external cooling is studied through a highly sophisticated scheme, called louver, which combines the effects of impingement and film cooling. Pin fins and ribs turbulator geometries applied in the channel between the impingement and the film cooling have the purpose of evaluating the impact of these geometries on the film cooling effectiveness over the flat surface in comparison to the louver scheme without turbulator. This study concluded that, pin fins proved to be the most promise solution because they increased in 7% the film cooling effectiveness. Ribs also have a good potential to increase the effectiveness, because an increase of 4% in film cooling effectiveness was observed. In addition, the effects of the turbulator are dependent on their location, since the turbulator positioned near the film cooling hole exit showed improvements in the film cooling effectiveness in relation to the turbulator near of the impingement cooling jet.
20.	Dahal, Karna, 1984, et al. (author) Techno-economic review of alternative fuels and propulsion systems for the aviation sector 2021 In: Renewable and Sustainable Energy Reviews. - : Elsevier BV. - 1879-0690 .- 1364-0321. ; 151 Research review (peer-reviewed)abstract Substitution of conventional jet fuel with low-to zero-carbon-emitting alternative aviation fuels is vital for meeting the climate targets for aviation. It is important to understand the technical, environmental, and economic performance of alternative aviation fuels and prospective engine and propulsion technologies for future aircraft. This study reviews alternative fuels and propulsion systems, focusing on costs and technical maturity, and presents conceptual aircraft designs for different aviation fuels. The cost review includes minimum jet fuel selling price (MJFSP) for alternative aviation fuels. Direct operating cost (DOC) is estimated based on the conceptual aircraft designs and the reviewed MJFSP. The DOCs for bio-jet fuel (5.0–9.2 US cent per passenger-kilometer (¢/PAX/km)), fossil and renewable liquefied hydrogen (5.9–10.1 and 8.1–23.9 ¢/PAX/km, respectively), and electro-methane and electro-jet fuel (5.6–16.7 and 9.2–23.7 ¢/PAX/km, respectively) are higher than for conventional jet fuel (3.9–4.8 ¢/PAX/km) and liquefied natural gas (4.2–5.2 ¢/PAX/km). Overall, DOC of renewable aviation fuels is 15–500 % higher than conventional jet fuels. Among the bio-jet fuels, hydroprocessed esters and fatty acids (23–310 $/GJ) and alcohol-to-jet (4–215 $/GJ) pathways offer the lowest MJFSPs. The implementation of alternative fuels in existing aircraft engines and the design and development of appropriate propulsion systems and aircraft are challenging. The overall cost is a key factor for future implementation. Bio-jet fuel is most promising in the near term while hydrogen and electrofuels in the long term. The level of carbon tax on fossil jet fuels needed for the latter options to be competitive depend on the hydrogen production cost.
21.	De Campos, Gustavo Bonolo, et al. (author) Propulsive efficiency of boundary layer ingestion propellers 2018 In: 31st Congress of the International Council of the Aeronautical Sciences, ICAS 2018. Conference paper (peer-reviewed)abstract The pursuit of lower fuel consumption for aircraft is promoting a departure from contemporary arrangements. One example is the development of more synergetic airframe and propulsion system designs, which are expected to increase significantly aircraft efficiency mainly by means of boundary layer ingestion. By integrating propulsion and airframe, both systems will significantly impact each other. This mutual interference requires the development of novel performance evaluation methods that consider such effects. This manuscript introduces a propulsive efficiency equation for boundary layer ingestion propellers based on the power balance method. Two formulations are presented for numerical and analytical evaluations. The equation is bounded between 0 and 1 and allows a meaningful evaluation of shaft to propulsive powers conversion, which results in an accurate determination of thrust and drag. This manuscript is the first advance of a project that will develop an optimizing tool for boundary layer ingestion propellers based on computational fluid dynamic simulations. The results will be presented in subsequent manuscripts.
22.	Ekstrand, Henrik, 1975, et al. (author) An environmental assessment of air traffic speed constraints in the departure phase of flight: A case study at Gothenburg Landvetter Airport, Sweden 2012 In: Transportation Research Part D: Transport and Environment. - : Elsevier BV. - 1361-9209. ; 17:8, s. 610-618 Journal article (peer-reviewed)abstract This paper considers the environmental effects of airtraffic management speed constraints during the departure phase of flight. We present a CO2 versus noise trade-off study that compares aircraft departure procedures subject to speed constraints with a free speed scenario. A departure route at Gothenburg Landvetter Airport in Sweden is used as a case study and the analysis is based on airline flight recorded data extracted from the Airbus A321 aircraft. Results suggest that CO2 emissions could be reduced by 180 kg per flight if all departure speed constraints were removed at a cost of increased noise exposure below 70 dB(A).
23.	Ekstrand, Henrik, 1975, et al. (author) Derated Climb Trajectories for Subsonic Transport Aircraft 2009 In: PROCEEDINGS XIX INTERNATIONAL SYMPOSIUM ON AIR BREATHING ENGINES. Conference paper (peer-reviewed)abstract Minimising the overall operating cost with regard toengine deterioration during takeoff by using deratedtakeoff thrust is well understood by aircraft andengine manufacturers. Some aircraft have thepossibility to use derated climb thrust as well, whichis not always fully understood by the operators. Thepossibility of using derated climb thrust for reducingmaintenance costs is discussed. It is shown that byusing derated climb thrust D2, the HPT blade life canbe increased by 7 % at the expense of a 0.7 %increase in fuel consumption during the climb phase,affecting the overall flight mission fuel consumptionby approximately 0.1 %.
24.	Giuliani, Fabrice, et al. (author) EFFECTS OF A CONTROLLED PHASE-SHIFT ON THE OUTLET CONDITIONS OF A SET OF PULSE DETONATORS 2009 In: PROCEEDINGS XIX International Symposium on Air Breathing Engines. Conference paper (peer-reviewed)abstract A study on innovative combustion system for future aeroengine core concepts is done in the frame ofthe NEWAC project. A part of the high pressure core is replaced by a pulse detonation combustor. The ambition is to achieve a technical leap in TSFC reduction. In order toprovide technical assessments on both the feasibility and the performance of such a concept, specific tools were developed at TU Graz and Chalmers and are herebypresented and validated. The approach consists in a simultaneous averaged approach at system level,combined to a real-time simulation of the flow intermittency and its possible impact on the ambient. Theeffect of a phase-shift on the operation of neighbour tubescomposing a PDC is analysed into details.
25.	Grewe, V., et al. (author) Evaluating the climate impact of aviation emission scenarios towards the Paris agreement including COVID-19 effects 2021 In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 12:1 Journal article (peer-reviewed)abstract Aviation is an important contributor to the global economy, satisfying society’s mobility needs. It contributes to climate change through CO2 and non-CO2 effects, including contrail-cirrus and ozone formation. There is currently significant interest in policies, regulations and research aiming to reduce aviation’s climate impact. Here we model the effect of these measures on global warming and perform a bottom-up analysis of potential technical improvements, challenging the assumptions of the targets for the sector with a number of scenarios up to 2100. We show that although the emissions targets for aviation are in line with the overall goals of the Paris Agreement, there is a high likelihood that the climate impact of aviation will not meet these goals. Our assessment includes feasible technological advancements and the availability of sustainable aviation fuels. This conclusion is robust for several COVID-19 recovery scenarios, including changes in travel behaviour.

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