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1
STEPAN, Anca, Georges GHAZI i Ruxandra Mihaela BOTEZ. "Development of an Adaptive Aero-Propulsive Performance Model in Cruise Flight – Application to the Cessna Citation X". INCAS BULLETIN 14, nr 4 (2.12.2022): 167–81. http://dx.doi.org/10.13111/2066-8201.2022.14.4.14.
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To accurately predict the amount of fuel needed by an aircraft for a given flight, a performance model must account for engine and airframe degradation. This paper presents a methodology to identify an aero-propulsive model to predict the fuel flow of an aircraft in cruise, while considering initial modeling uncertainties and performance variation over time due to degradation. Starting from performance data obtained from a Research Aircraft Flight Simulator, an initial aero-propulsive model was identified using different estimation methods. The estimation methods studied in this paper were polynomial interpolation, thin-plate splines, and neural networks. The aero-propulsive model was then structured using two lookup tables: one lookup table reflecting the aerodynamic performance, and another table reflecting the propulsive performance. Subsequently, an adaptative technique was developed to locally and then globally, adapt the lookup tables defining the aero-propulsive model using flight data. The methodology was applied to the Cessna Citation X business jet aircraft, for which a highly qualified level D research aircraft flight simulator was available. The results demonstrated that by using the proposed aero-propulsive performance model, it was possible to predict the aerodynamic performance with an average relative error of 0.99%, and the propulsive performance with an average relative error of 3.38%. These results were obtained using the neural network estimation method.
2
Zhao, Wenyuan, Yanlai Zhang, Peng Tang i Jianghao Wu. "The Impact of Distributed Propulsion on the Aerodynamic Characteristics of a Blended-Wing-Body Aircraft". Aerospace 9, nr 11 (10.11.2022): 704. http://dx.doi.org/10.3390/aerospace9110704.
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Motivated by outstanding aerodynamic performance and limited emissions, the blend-wing-body (BWB) aircraft equipped with a distributed propulsion (DP) system has become a possible layout for civil aircraft in the next generation. Due to the strong aero-propulsive interference (API) between the DP system and the airframe, the conventional integration of pressure and friction stress over the surface may fail to evaluate the aerodynamic power consumption of this layout. Here, the aero-propulsive integrated power balance approach is used alternatively to obtain the aerodynamic power consumption through flow data. We demonstrate that the API effects can enlarge both the lift and aerodynamic power consumption of this layout. The increase in power consumption is attributed to the enhanced viscous dissipation rate within the boundary layer. Wind tunnel experiments further demonstrate that the operation of the DP system can improve the stall characteristics. Our findings encourage limiting the inflow speed of the DP system to alleviate the enhancement in viscous dissipation rate and thus reduce the power consumption.
3
Luo, Shaojun, Tian Zi Eng, Zhili Tang, Qianrong Ma, Jinyou Su i Gabriel Bugeda. "Multidisciplinary Optimization of Aircraft Aerodynamics for Distributed Propulsion Configurations". Applied Sciences 14, nr 17 (3.09.2024): 7781. http://dx.doi.org/10.3390/app14177781.
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The combination of different aerodynamic configurations and propulsion systems, namely, aero-propulsion, affects flight performance differently. These effects are closely related to multidisciplinary collaborative aspects (aerodynamic configuration, propulsion, energy, control systems, etc.) and determine the overall energy consumption of an aircraft. The potential benefits of distributed propulsion (DP) involve propulsive efficiency, energy-saving, and emissions reduction. In particular, wake filling is maximized when the trailing edge of a blended wing body (BWB) is fully covered by propulsion systems that employ boundary layer ingestion (BLI). Nonetheless, the thrust–drag imbalance that frequently arises at the trailing edge, excessive energy consumption, and flow distortions during propulsion remain unsolved challenges. These after-effects imply the complexity of DP systems in multidisciplinary optimization (MDO). To coordinate the different functions of the aero-propulsive configuration, the application of MDO is essential for intellectualized modulate layout, thrust manipulation, and energy efficiency. This paper presents the research challenges of ultra-high-dimensional optimization objectives and design variables in the current literature in aerodynamic configuration integrated DP. The benefits and defects of various coupled conditions and feasible proposals have been listed. Contemporary advanced energy systems, propulsion control, and influential technologies that are energy-saving are discussed. Based on the proposed technical benchmarks and the algorithm of MDO, the propulsive configuration that might affect energy efficiency is summarized. Moreover, suggestions are drawn for forthcoming exploitation and studies.
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Seitz, Arne, Anaïs Luisa Habermann, Fabian Peter, Florian Troeltsch, Alejandro Castillo Pardo, Biagio Della Corte, Martijn van Sluis i in. "Proof of Concept Study for Fuselage Boundary Layer Ingesting Propulsion". Aerospace 8, nr 1 (13.01.2021): 16. http://dx.doi.org/10.3390/aerospace8010016.
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Key results from the EU H2020 project CENTRELINE are presented. The research activities undertaken to demonstrate the proof of concept (technology readiness level—TRL 3) for the so-called propulsive fuselage concept (PFC) for fuselage wake-filling propulsion integration are discussed. The technology application case in the wide-body market segment is motivated. The developed performance bookkeeping scheme for fuselage boundary layer ingestion (BLI) propulsion integration is reviewed. The results of the 2D aerodynamic shape optimization for the bare PFC configuration are presented. Key findings from the high-fidelity aero-numerical simulation and aerodynamic validation testing, i.e., the overall aircraft wind tunnel and the BLI fan rig test campaigns, are discussed. The design results for the architectural concept, systems integration and electric machinery pre-design for the fuselage fan turbo-electric power train are summarized. The design and performance implications on the main power plants are analyzed. Conceptual design solutions for the mechanical and aero-structural integration of the BLI propulsive device are introduced. Key heuristics deduced for PFC conceptual aircraft design are presented. Assessments of fuel burn, NOx emissions, and noise are presented for the PFC aircraft and benchmarked against advanced conventional technology for an entry-into-service in 2035. The PFC design mission fuel benefit based on 2D optimized PFC aero-shaping is 4.7%.
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Baklacioglu, T., i M. Cavcar. "Aero-propulsive modelling for climb and descent trajectory prediction of transport aircraft using genetic algorithms". Aeronautical Journal 118, nr 1199 (styczeń 2014): 65–79. http://dx.doi.org/10.1017/s0001924000008939.
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Abstract In this study, a new aero-propulsive model (APM) was derived from the flight manual data of a transport aircraft using Genetic Algorithms (GAs) to perform accurate trajectory predictions. This new GA-based APM provided several improvements to the existing models. The use of GAs enhanced the accuracy of both propulsive and aerodynamic modelling. The effect of compressible drag rise above the critical Mach number, which was not included in previous models, was considered along with the effects of compressibility and profile camber in the aerodynamic model. Consideration of the thrust dependency with respect to Mach number and the altitude in the propulsive model expression was observed to be a more practical approach. The proposed GA model successfully predicted the trajectory for the descent phase, as well, which was not possible in previous models. Close agreement was observed when comparing the time to climb and time to descent values obtained from the model with the flight manual data.
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Swain, Prafulla Kumar, Ashok K. Barik, Siva Prasad Dora i Rajeswara Resapu. "The propulsion of tandem flapping foil following fishtailed flapping trajectory". Physics of Fluids 34, nr 12 (grudzień 2022): 123609. http://dx.doi.org/10.1063/5.0128223.
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It has always been a challenge to implement the natural flyer and swimmer kinematics into human-made aero/hydro vehicles for the enhancement of their performance. The propulsive performance of underwater vehicles can be enhanced by following the fishtailed kinematics. In the present study, a two-dimensional simulation has been performed on a tandem flapping foil by altering the simple flapping trajectory motion to a fishtailed trajectory by varying the Strouhal number ( St) in the range of 0.1–0.5. The effect of the inter-foil spacing and phasing between the foils on wake interaction is also investigated. The results show that fishtailed trajectory motion and inter-foil spacing of 2 cm–3 cm (where cm is the mean chord length) between the foils would enhance the propulsive efficiency of the downstream foil by up to 41%. The unfavorable spacing between the foils results in adverse wake interaction, which reduces the propulsive efficiency compared to solo flapping foil.
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Yin, F., i A. Gangoli Rao. "Performance analysis of an aero engine with inter-stage turbine burner". Aeronautical Journal 121, nr 1245 (4.09.2017): 1605–26. http://dx.doi.org/10.1017/aer.2017.93.
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ABSTRACTThe historical trends of reduction in fuel consumption and emissions from aero engines have been mainly due to the improvement in the thermal efficiency, propulsive efficiency and combustion technology. The engine Overall Pressure Ratio (OPR) and Turbine Inlet Temperature (TIT) are being increased in the pursuit of increasing the engine thermal efficiency. However, this has an adverse effect on engine NOx emission. The current paper investigates a possible solution to overcome this problem for future generation Very High Bypass Ratio (VHBR)/Ultra High Bypass Ratio (UHBR) aero-engines in the form of an Inter-stage Turbine Burner (ITB). The ITB concept is investigated on a next generation baseline VHBR aero engine to evaluate its effect on the engine performance and emission characteristics for different ITB energy fractions. It is found that the ITB can reduce the bleed air required for cooling the HPT substantially (around 80%) and also reduce the NOx emission significantly (>30%) without penalising the engine specific fuel consumption.
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Corcione, Salvatore, Vincenzo Cusati, Danilo Ciliberti i Fabrizio Nicolosi. "Experimental Assessment of Aero-Propulsive Effects on a Large Turboprop Aircraft with Rear-Engine Installation". Aerospace 10, nr 1 (15.01.2023): 85. http://dx.doi.org/10.3390/aerospace10010085.
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This paper deals with the estimation of propulsive effects for a three-lifting surface turboprop aircraft concept, with rear engine installation at the horizontal tail tips, conceived to carry up to 130 passengers. This work is focused on how the propulsive system affects the horizontal tailplane aerodynamics and, consequently, the aircraft’s static stability characteristics using wind tunnel tests. Both direct and indirect propulsive effects have been estimated. The former produces moments whose values depend on the distance from the aircraft’s centre of gravity to the thrust lines and propeller disks. The latter entails a change in the angle of attack and an increment of dynamic pressure on the tailplane. Several tests were also performed on the body-empennage configuration to investigate the propulsive effects on the aircraft’s static stability without the appearance of any aerodynamic interference phenomena, especially from the canard. The output of the experimental campaign reveals a beneficial effect of the propulsive effects on the aircraft’s longitudinal stability, with an increase in the stability margin of about 2.5% and a reduction in the directional stability derivative of about 4%, attributed to the different induced drag contributions of the two horizontal tail semi-planes. Moreover, the rolling moment coefficient experiences a greater variation due to the propulsion depending on the propeller rotation direction. The outcomes of this paper allow the enhancement of the technical readiness level for the considered aircraft, giving clear indications about the feasibility of the aircraft configuration.
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Minucci, Marco A. S., i Leik N. Myrabo. "Phase distortion in a propulsive laser beam due to aero-optical phenomena". Journal of Propulsion and Power 6, nr 4 (lipiec 1990): 416–25. http://dx.doi.org/10.2514/3.25452.
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Perry, Aaron T., Phillip J. Ansell i Michael F. Kerho. "Aero-Propulsive and Propulsor Cross-Coupling Effects on a Distributed Propulsion System". Journal of Aircraft 55, nr 6 (listopad 2018): 2414–26. http://dx.doi.org/10.2514/1.c034861.
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Omran, Ashraf, Brett Newman i Drew Landman. "Global aircraft aero-propulsive linear parameter-varying model using design of experiments". Aerospace Science and Technology 22, nr 1 (październik 2012): 31–44. http://dx.doi.org/10.1016/j.ast.2011.05.008.
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Ciliberti, Danilo, Pierluigi Della Vecchia, Vincenzo Orticalco i Fabrizio Nicolosi. "Aero-Propulsive Interactions between UAV Wing and Distributed Propellers Due to Their Relative Position". Drones 7, nr 1 (11.01.2023): 49. http://dx.doi.org/10.3390/drones7010049.
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The purpose of this paper is the evaluation of the aero-propulsive effects on a UAV wing model with distributed propulsion. An array of three propellers is placed ahead of the leading edge of a rectangular wing with flap. The investigation was performed with high-fidelity numerical analyses to provide insights into the phenomenology and to screen the interesting positions to be validated in the wind tunnel. The propellers’ array is moved into twelve different positions, allowing longitudinal and vertical translations. The wing has an untwisted and constant section profile, with a single slot trailing-edge flap that is deflected into three positions. The flap span is entirely covered by the propellers’ blowing. Results show an increment of lift, drag, and pitching moment coefficients with distributed propellers enabled. For a given thrust level, the magnitude of such increments depends on the propellers’ positions, the flap configuration, and the angle of attack. The lift enhancement sought in distributed propulsion applications comes at the expense of a significant increase in drag and pitching moment magnitude. In some combinations, the wing’s contribution to the aircraft longitudinal stability is severely affected. Conversely, the propellers’ inflow is altered such that thrust is increased in all the investigated configurations, with a small reduction of propulsive efficiency.
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Jeong, In-Ho, i Hyeong-Geun Kim. "Nonlinear Control for Missile Autopilot Based on Control Allocation for Dual Aero/Propulsive Inputs". Journal of Institute of Control, Robotics and Systems 29, nr 8 (31.08.2023): 584–91. http://dx.doi.org/10.5302/j.icros.2023.23.0055.
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Jasa, John P., Benjamin J. Brelje, Justin S. Gray, Charles A. Mader i Joaquim R. R. A. Martins. "Large-Scale Path-Dependent Optimization of Supersonic Aircraft". Aerospace 7, nr 10 (20.10.2020): 152. http://dx.doi.org/10.3390/aerospace7100152.
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Aircraft are multidisciplinary systems that are challenging to design due to interactions between the subsystems. The relevant disciplines, such as aerodynamic, thermal, and propulsion systems, must be considered simultaneously using a path-dependent formulation to assess aircraft performance accurately. In this paper, we construct a coupled aero-thermal-propulsive-mission multidisciplinary model to optimize supersonic aircraft considering their path-dependent performance. This large-scale optimization problem captures non-intuitive design trades that single disciplinary models and path-independent methods cannot resolve. We present optimal flight profiles for a supersonic aircraft with and without thermal constraints. We find that the optimal flight trajectory depends on thermal system performance, showing the need to optimize considering the path-dependent multidisciplinary interactions.
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Chudoba, B., G. Coleman, L. Gonzalez, E. Haney, A. Oza i V. Ricketts. "Orbital transfer vehicle (OTV) system sizing study for manned GEO satellite servicing". Aeronautical Journal 120, nr 1226 (kwiecień 2016): 573–99. http://dx.doi.org/10.1017/aer.2016.3.
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ABSTRACTIn an effort to quantify the feasibility of candidate space architectures for astronauts servicing Geosynchronous Earth Orbit (GEO) satellites, a conceptual assessment of architecture-concept and operations-technology combinations has been performed. The focus has been the development of a system with the capability to transfer payload to and from geostationary orbit. Two primary concepts of operations have been selected: (a) Direct insertion/re-entry (Concept of Operations 1 – CONOP 1); (b) Launch to low-earth orbit at Kennedy Space Center inclination angle with an orbital transfer to/from geostationary orbit (Concept of Operations 2 – CONOP 2). The study concludes that a capsule and de-orbit propulsion module system sized for the geostationary satellite servicing mission is feasible for a direct insertion/re-entry concept of operation CONOP 1. Vehicles sized for CONOP 2 show overall total mass savings when utilising the aero-assisted orbital transfer vehicle de-orbit propulsion module options compared to the pure propulsive baseline cases. Overall, the consideration of technical, operational and cost factors determine if either the aero-assisted orbital transfer vehicle concepts or the re-usable/expendable ascent/de-orbit propulsion modules is the preferred option.
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Goulos, I., J. Otter, T. Stankowski, D. Macmanus, N. Grech i C. Sheaf. "Design optimisation of separate-jet exhausts for the next generation of civil aero-engines". Aeronautical Journal 122, nr 1256 (19.09.2018): 1586–605. http://dx.doi.org/10.1017/aer.2018.95.
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ABSTRACTThe next generation of civil large aero-engines will employ greater bypass ratios compared with contemporary architectures. This results in higher exchange rates between exhaust performance and specific fuel consumption (SFC). Concurrently, the aerodynamic design of the exhaust is expected to play a key role in the success of future turbofans. This paper presents the development of a computational framework for the aerodynamic design of separate-jet exhaust systems for civil aero-engines. A mathematical approach is synthesised based on class-shape transformation (CST) functions for the parametric geometry definition of gas-turbine exhaust components such as annular ducts and nozzles. This geometry formulation is coupled with an automated viscous and compressible flow solution method and a cost-effective design space exploration (DSE) approach. The framework is deployed to optimise the performance of a separate-jet exhaust for very-high-bypass ratio (VHBR) turbofan engine. The optimisations carried out suggest the potential to increase the engine’s net propulsive force compared with a baseline architecture, through optimum exhaust re-design. The proposed method is able to identify and alleviate adverse flow-features that may deteriorate the aerodynamic behaviour of the exhaust system.
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Dong, Yiwei, Weiguo Yan, Tao Liao, Qianwen Ye i Yancheng You. "Model characterization and mechanical property analysis of bimetallic functionally graded turbine discs". Mechanics & Industry 22 (2021): 4. http://dx.doi.org/10.1051/meca/2021001.
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In advanced propulsive systems, a turbine disc bears vast mechanical and thermal loads under its working conditions of high-temperature gradients and high rotational velocity.The complex working conditions of aero-engine turbine discs place stringent performance requirements on the materials used. With dual organizations and superior composite performances, bimetallic functionally graded turbine discs have become a focus in the research of high thrust-to-weight ratio aero-engines. To study the mechanical properties of new bimetallic functionally graded materials under service conditions, we propose a volumetric fraction expression and adjustable composition distribution parameters that are suitable for simulating the composition distribution of bimetallic functionally graded turbine discs. On this basis, a characterization model for functionally graded materials based on the analysis of the internal thermodynamic properties of bimetallic turbine discs is established. The thermodynamic properties and fatigue performances of functionally graded materials under service conditions are analysed. Mechanical property simulations of functionally graded turbine discs are performed using different composition distribution parameters, and reasonable ranges are determined for the various composition distribution parameters. The results show that bimetallic functionally graded turbine discs are suitable for high-stress-gradient and high-temperature-gradient environments with lower weights than those of current GH4169 alloy turbine discs.
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Daniel, Thomas L. "Forward flapping flight from flexible fins". Canadian Journal of Zoology 66, nr 3 (1.03.1988): 630–38. http://dx.doi.org/10.1139/z88-094.
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The mechanics and energetics of aquatic flight by the clearnose skate (Raja eglanteria) are examined with cinefilm and a new theoretical approach toward flight mechanics. Film analyses show that these animals move with a flapping, flexing wing that has a propulsive wave travelling rearward at twice the forward speed of the animal. A combination of blade-element theory and unsteady airfoil theory is used to examine the mechanics and energetics of this mode of locomotion. The theoretical analysis shows that (i) unsteady effects determine the overall performance of the wings, and (ii) there exist wing shapes that minimize the cost of transport or maximize the thrust. The theory indicates that the wings of swimming skates closely approach the minimum cost of transport. The results are extended to explore other modes of flapping wing propulsion, including those in animals whose wings deform passively in response to hydro- or aero-dynamic loads.
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Cilgin, Mehmet Emin, i Onder Turan. "Entropy Generation Calculation of a Turbofan Engine: A Case of CFM56-7B". International Journal of Turbo & Jet-Engines 35, nr 3 (26.07.2018): 217–27. http://dx.doi.org/10.1515/tjj-2017-0053.
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Abstract Entropy generation and energy efficiency of turbofan engines become greater concern in recent years caused by rises fuel costs and as well as environmental impact of aviation emissions. This study describes calculation of entropy generation for a two-spool CFM56-7B high-bypass turbofan widely used on short to medium range, narrow body aircrafts. Entropy generation and power analyses are performed for five main engine components obtaining temperature-entropy, entropy-enthalpy, pressure-volume diagrams at ≈121 kN take-off thrust force. In the study, maximum entropy production is determined to be 0.8504 kJ/kg K at the combustor, while minimum entropy generation is observed at the low pressure compressor component with the value of 0.0025 kJ/kg K. Besides, overall efficiency of the turbofan is determined to be 14 %, while propulsive and thermal efficiencies of the engine are 35 % and 40 %, respectively. As a conclusion, this study aims to show increase of entropy due to irreversibilities and produced power dimension in engine components for commercial turbofans and aero-derivative cogeneration power plants.
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Rolt, Andrew, Vishal Sethi, Florian Jacob, Joshua Sebastiampillai, Carlos Xisto, Tomas Grönstedt i Lorenzo Raffaelli. "Scale effects on conventional and intercooled turbofan engine performance". Aeronautical Journal 121, nr 1242 (8.06.2017): 1162–85. http://dx.doi.org/10.1017/aer.2017.38.
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ABSTRACTNew commercial aero engines for 2050 are expected to have lower specific thrusts for reduced noise and improved propulsive efficiency, but meeting the ACARE Flightpath 2050 fuel-burn and emissions targets will also need radical design changes to improve core thermal efficiency. Intercooling, recuperation, inter-turbine combustion and added topping and bottoming cycles all have the potential to improve thermal efficiency. However, these new technologies tend to increase core specific power and reduce core mass flow, giving smaller and less efficient core components. Turbine cooling also gets more difficult as engine cores get smaller. The core-size-dependent performance penalties will become increasingly significant with the development of more aerodynamically efficient and lighter-weight aircraft having lower thrust requirements. In this study the effects of engine thrust and core size on performance are investigated for conventional and intercooled aeroengine cycles. Large intercooled engines could have 3%–4% SFC improvement relative to conventional cycle engines, while smaller engines may only realize half of this benefit. The study provides a foundation for investigations of more complex cycles in the EU Horizon 2020 ULTIMATE programme.
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Zhang, Jing, Xianfa Zeng i Lingyu Yang. "Model-based analysis of boundary layer ingestion effect on lateral-directional aerodynamics using differentiated boundary conditions". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 231, nr 13 (14.09.2016): 2452–63. http://dx.doi.org/10.1177/0954410016667148.
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The noteworthy feature of aircraft with distributed propulsion configuration is the integration of a blended-wing-body type airframe and an embedded distributed propulsion system, thus inducing the specific boundary layer ingestion effect. Different boundary layer ingestion effects on the distributed engines may generate asymmetric flow fields on the airframe surface, and then lead to the unique lateral-directional aero-propulsive close coupling. To investigate the lateral-directional aerodynamics influenced by boundary layer ingestion, a new comprehensive computational method based on the differentiated boundary conditions is proposed. This method uses a synthetic three-dimensional computational model including the airframe and multi-engine to analyze the aerodynamic characteristics, and the essential boundary conditions can be extracted from the thermodynamic distributed propulsion system model to represent the different boundary layer ingestion intensities on the left and right engines. Subsequently, detailed model-based analyses of boundary layer ingestion influences on the lateral-directional aerodynamic characteristics are conducted, and the influence regularities under different flight states are revealed. All the results demonstrate that the differentiated boundary layer ingestion intensities on distributed engines can certainly affect the roll and yaw aerodynamic performance of the distributed propulsion configuration aircraft.
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Ciliberti, Danilo, Pierluigi Della Vecchia, Vittorio Memmolo, Fabrizio Nicolosi, Guido Wortmann i Fabrizio Ricci. "The Enabling Technologies for a Quasi-Zero Emissions Commuter Aircraft". Aerospace 9, nr 6 (12.06.2022): 319. http://dx.doi.org/10.3390/aerospace9060319.
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The desire for greener aircraft pushes both academic and industrial research into developing technologies, manufacturing, and operational strategies providing emissions abatement. At time of writing, there are no certified electric aircraft for passengers’ transport. This is due to the requirements of lightness, reliability, safety, comfort, and operational capability of the fast air transport, which are not completely met by the state-of-the-art technology. Recent studies have shown that new aero-propulsive technologies do not provide significant fuel burn reduction, unless the operational ranges are limited to short regional routes or the electric storage capability is unrealistically high, and that this little advantage comes at increased gross weight and operational costs. Therefore, a significant impact into aviation emissions reduction can only be obtained with a revolutionary design, which integrates disruptive technologies starting from the preliminary design phase. This paper reviews the recent advances in propulsions, aerodynamics, and structures to present the enabling technologies for a low emissions aircraft, with a focus on the commuter category. In fact, it is the opinion of the European Community, which has financed several projects, that advances on the small air transport will be a fundamental step to assess the results and pave the way for large greener airplanes.
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Memmolo, V., F. Orefice, F. Nicolosi i F. Ricci. "Design of near-zero emission aircraft based on refined aerodynamic model and structural analysis". IOP Conference Series: Materials Science and Engineering 1226, nr 1 (1.02.2022): 012067. http://dx.doi.org/10.1088/1757-899x/1226/1/012067.
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Abstract During recent years, aircraft manufacturers focused their attention on environmentally friendly and aerodynamically efficient aircraft concepts that could allow a radical reduction of emissions. The use of hybrid-electric powertrain is one of the most effective ways to design near-zero emission aircraft. These aircraft are highly performing and sophisticated. Hence, the design process must be extremely accurate and should make use of multidisciplinary design optimization. It is indeed crucial to establish both aerodynamic and structural models to simulate the aircraft performance and design required according to top level aircraft requirements. Despite the largely discussed literature about preliminary design of such an unconventional aircraft, there is still a lack of reliable weight estimation approaches, simulation-based mission analysis and optimization tools. In order to step towards higher technological readiness levels, the purpose of this paper is to describe and apply a design platform for conventional, turboelectric, hybrid-electric and full-electric aircraft, integrating aero-propulsive interactions, accurate power system modelling and medium-fidelity structural weight estimation. In particular, the comprehensive structural analysis of the aircraft wing opportunely designed according to certification specification and equipped with different powertrain architectures shows that it is worth looking into structural dynamics from preliminary design to estimate aircraft weight properly. Meanwhile, the mission analysis reveals performance benefits by implementing distributed engines all over the wingspan.
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Parker, R., i M. Lathoud. "Green aero-engines: Technology to mitigate aviation impact on environment". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 224, nr 3 (12.01.2010): 529–38. http://dx.doi.org/10.1243/09544062jmes1515.
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Despite consistent, continued efforts by the aviation industry to reduce emissions, further technological advances are required to mitigate its impact on the global climate. This article first outlines aviation's importance in the global challenge and its specific constraints relative to other industries. It then investigates the current understanding of aviation's climate impact and the ongoing Rolls-Royce efforts to develop technologies to mitigate it. This includes improving the engine's propulsive efficiency, thermal efficiency, and combustion process. This article also discusses paradigm shifts that might redefine the way this industry operates in the global environment.
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Figueira, João C., Sean Bazzocchi, Stephen Warwick i Afzal Suleman. "Nonlinear Aero-Propulsive Modeling for Fixed-Wing eVTOL UAV from Flight Test Data". Journal of Aircraft, 18.11.2024, 1–13. http://dx.doi.org/10.2514/1.c037964.
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This paper presents a methodology for constructing an aero-propulsive system identification model for a fixed-wing propeller-driven aircraft with limited flight data. Developing a flight dynamics model is an iterative process involving costly and time-consuming flight testing to collect relevant data. To maximize the utilization of available data, this study employs a time-domain system identification procedure on flight data from various maneuvers and flights. The methodology incorporates multivariate orthogonal functions to capture the nonlinear terms representing the coupled effects of the propeller and airframe dynamics. A stepwise regression is then employed to identify the most pertinent model parameters. Estimation of variables associated with the propulsive contribution is accomplished through an electrical propulsive model, identified using command and battery data from static thrust and flight tests. Aero-propulsive derivatives are determined using the output-error method, where the accuracy is assessed based on a colored noise correction. To validate the predictability of the flight dynamics model, out-of-sample data are employed. The construction of the electrical propulsive model and identification of aerodynamic derivatives from flight data were specifically carried out for a particular eVTOL flight test vehicle; however, the techniques employed are generalizable and applicable to other aircraft models.
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Keller, Dennis. "Towards higher aerodynamic efficiency of propeller-driven aircraft with distributed propulsion". CEAS Aeronautical Journal, 17.08.2021. http://dx.doi.org/10.1007/s13272-021-00535-5.
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AbstractThe scope of the present paper is to assess the potential of distributed propulsion for a regional aircraft regarding aero-propulsive efficiency. Several sensitivities such as the effect of wingtip propellers, thrust distribution, and shape modifications are investigated based on a configuration with 12 propulsors. Furthermore, an initial assessment of the high-lift performance is undertaken in order to estimate potential wing sizing effects. The performance of the main wing and the propellers are thereby equally considered with the required power being the overall performance indicator. The results indicate that distributed propulsion is not necessarily beneficial regarding the aero-propulsive efficiency in cruise flight. However, the use of wing tip propellers, optimization of the thrust distribution, and wing resizing effects lead to a reduction in required propulsive power by $$-2.9$$ - 2.9 to $$-3.3\,\%$$ - 3.3 % compared to a configuration with two propulsors. Adapting the leading edge to the local flow conditions did not show any substantial improvement in cruise configuration to date.
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Seitz, Arne, Anaïs Luisa Habermann i Martijn van Sluis. "Optimality considerations for propulsive fuselage power savings". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, 8.04.2020, 095441002091631. http://dx.doi.org/10.1177/0954410020916319.
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The paper discusses optimality constellations for the design of boundary layer ingesting propulsive fuselage concept aircraft under special consideration of different fuselage fan power train options. Therefore, a rigorous methodical approach for the evaluation of the power saving potentials of propulsive fuselage concept aircraft configurations is provided. Analytical formulation for the power-saving coefficient metric is introduced, and, the classic Breguet–Coffin range equation is extended for the analytical assessment of boundary layer ingesting aircraft fuel burn. The analytical formulation is applied to the identification of optimum propulsive fuselage concept power savings together with computational fluid dynamics numerical results of refined and optimised 2D aero-shapings of the bare propulsive fuselage concept configuration, i.e. fuselage body including the aft–fuselage boundary layer ingesting propulsive device, obtained during the European Union-funded DisPURSAL and CENTRELINE projects. A common heuristic for the boundary layer ingesting efficiency factor is derived from the best aero-shaping cases of both projects. Based thereon, propulsive fuselage concept aircraft design optimality is parametrically analysed against variations in fuselage fan power train efficiency, systems weight impact and fuselage-to-overall aircraft drag ratio in cruise. Optimum power split ratios between the fuselage fan and the underwing main fans are identified. The paper introduces and discusses all assumptions necessary in order to apply the presented evaluation approach. This includes an in-depth explanation of the adopted system efficiency definitions and drag/thrust bookkeeping standards.
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Bhandarkar, Anand, M. S. R. Chandra Murty, P. Manna i Debasis Chakraborty. "CFD Driven Aero-Propulsive Design of a Ducted Ramjet Missile". Journal of Aerospace Sciences and Technologies, 29.07.2023, 281–88. http://dx.doi.org/10.61653/joast.v71i3.2019.149.
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Detailed Computational Fluid Dynamics (CFD) simulations are carried out for a ducted ramjet missile. Combined internal and external flow fields are numerically simulated by solving 3D RANS equations along with Menter’s SST turbulence model. Aero-propulsive configuration is evolved progressively by improving radome shape, intake ramps, intake bleed system, diverter height etc. Numerical simulations have revealed that ogive radome has less drag compared to power law shaped radome and provide better flow characteristics at the intake entry leading to superior intake performance. Appropriate boundary layer diverter height and bleed system in the intake improve the intake performance. Aero-propulsive performance of the complete vehicle is estimated for different Mach numbers and angles of attack. It is demonstrated that improved performance of the ducted ramjet missile can be obtained through use of high fidelity numerical method.
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Simmons, Benjamin M., James L. Gresham i Craig A. Woolsey. "Aero-Propulsive Modeling for Propeller Aircraft Using Flight Data". Journal of Aircraft, 29.07.2022, 1–16. http://dx.doi.org/10.2514/1.c036773.
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Awad, Mohamed, i Eike Stumpf. "Aero-propulsive interaction model for conceptual distributed propulsion aircraft design". Aircraft Engineering and Aerospace Technology, 8.02.2022. http://dx.doi.org/10.1108/aeat-06-2021-0178.
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Purpose This research aims to present an aero-propulsive interaction model applied to conceptual aircraft design with distributed electric propulsion (DeP). The developed model includes a series of electric ducted fans integrated into the wing upper trailing edge, taking into account the effect of boundary layer ingestion (BLI). The developed model aims to estimate the aerodynamic performance of the wing with DeP using an accurate low-order computational model, which can be easily used in the overall aircraft design's optimization process. Design/methodology/approach First, the ducted fan aerodynamic performance is investigated using a low-order computational model over a range of angle of attack required for conventional flight based on ducted fan design code program and analytical models. Subsequently, the aero-propulsive coupling with the wing is introduced. The DeP location chordwise is placed at the wing's trailing edge to have the full benefits of the BLI. After that, the propulsion integration process is introduced. The nacelle design's primary function is to minimize the losses due to distortion. Finally, the aerodynamic forces of the overall configuration are estimated based on Athena Vortex Lattice program and the developed ducted fan model. Findings The ducted fan model is validated with experimental measurements from the literature. Subsequently, the overall model, the wing with DeP, is validated with experimental measurements and computational fluid dynamics, both from the literature. The results reveal that the currently developed model successfully estimates the aerodynamic performance of DeP located at the wing trailing edge. Originality/value The developed model's value is to capture the aero-propulsive coupling accurately and fast enough to execute multiple times in the overall aircraft design's optimization loop without increasing runtime substantially.
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Habermann, Anaïs Luisa, Anubhav Gokhale i Mirko Hornung. "Numerical investigation of the effects of fuselage upsweep in a propulsive fuselage concept". CEAS Aeronautical Journal, 6.01.2021. http://dx.doi.org/10.1007/s13272-020-00487-2.
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AbstractIn recent years, aircraft concepts employing wake-filling devices to reduce mission fuel burn have gained increasing attention. The study presented here aims at a detailed physical understanding of the effects of integrating a propulsive fuselage device on a commercial aircraft. Compared to an isolated, axisymmetric fuselage-propulsor configuration, a propulsive fuselage device experiences an increased circumferential inlet distortion due to three-dimensional geometric features of the aircraft. This study uses three-dimensional CFD simulations to investigate the effect of fuselage upsweep on the aero-propulsive performance of an aircraft configuration featuring a boundary layer ingestion device. It is shown that fuselage upsweep has a negative impact on the performance of a propulsive fuselage device as compared to an axisymmetric configuration. Increasing the upsweep angle by $$\Delta \alpha _{{{\text{SW}},{\text{PFC}}}} = 3.5^\circ$$ Δ α SW , PFC = 3 . 5 ∘ leads to an increase in required fuselage fan shaft power by 19%. Furthermore, it is demonstrated that the negative effects of fuselage upsweep on the propulsor’s performance can be effectively mitigated by a circumferential variation in the propulsor nacelle thickness.
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Balasubramanian, R., Jessy Prabhu Dayal, R. Krishnamurthy i Debasis Chakraborty. "Aero-Propulsive Characterization of a Flight Vehicle with Two Side-Jets". Journal of Aerospace Sciences and Technologies, 31.07.2023, 8–16. http://dx.doi.org/10.61653/joast.v68i1.2016.224.
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Numerical simulations were carried out to study the aero-propulsive characteristics of a flight vehicle using in-house developed Reynolds Averaged Navier-Stokes code CERANS. The analyses involved subsonic external flow with inclined supersonic dual sustainer jets at various angles of attack, roll orientations and side slip. The control characteristics of the configuration are evaluated for the flow with and without sustainer jets. Numerical simulations indicated that the jet plume exhausting out of the scarf sustainer nozzle grazed and clung to the airframe for a considerable downstream distance causing serious damage to the airframe. This numerical study led to an important design change of the sustainer nozzle shape from ‘scarf’ to ‘conical’ which alleviated plume interference problem with the airframe.
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Saccone, Guido, Ali Can Ispir, Bayindir Huseyin Saracoglu, Luigi Cutrone i Marco Marini. "Computational evaluations of emissions indexes released by the STRATOFLY air-breathing combined propulsive system". Aircraft Engineering and Aerospace Technology, 7.06.2022. http://dx.doi.org/10.1108/aeat-01-2022-0024.
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Purpose The purpose of this study is to provide the description of a computational methodology to model the combined propulsive systems of hydrogen propelled air-breathing scramjet vehicles and to evaluate the pollutant and climate-changing emissions. Design/methodology/approach Emissions indexes of nitrogen oxide (EINO) and water vapour released by the air turbo rocket (ATR) and dual mode ramjet (DMR) engines of the STRATOFLY air-breathing, hypersonic scramjet vehicle, propelled by hydrogen/air were evaluated. ATR engine operation was assessed for several cruise conditions in both subsonic and supersonic flight regimes in Ecosimpro software, which is an object-oriented thermodynamic design and simulation platform. ATR combustor inlet flow conditions play a key role in the computation of species mass fractions, and these conditions are highly dependent on turbomachinery performance and engine flight regime. A propulsive operational database was created by varying mass flow rates of fuel and flight conditions such as cruise speed and altitude to investigate possible engine operations. The all-inlet conditions in this map are provided to the Cantera-Python chemical/combustion chemistry solver implementing a specially designed and formulated 0D kinetic-thermodynamic methodology successfully used to model and simulate the electric spark ignition required to activate the combustion process of the reacting mixture in the ATR combustion chambers, whereas the coupled aero-thermodynamic/aero-propulsive 0D/1D code i.e. Scramjet PREliminary Aerothermodynamic Design (SPREAD), designed and developed by the Italian Aerospace Research Centre (CIRA) was used for DMR calculations. Results show low emissions of NO according to the optimized design of the ATR; on the other hand, a tuning of operational conditions is needed for DMR, with its complete re-design to be more conclusive. Analogously, the released amount of water vapour is in good agreement with the required combustion efficiency and the expected propulsive performance. Findings Results show low emissions of NO according to the optimized design of the ATRs; on the other hand, a tuning of operational conditions is needed for DMR, with its complete re-design to be more conclusive. Analogously, the released amount of water vapour is in good agreement with the required combustion efficiency and the expected propulsive performance. Originality/value Applications of innovative 0D/1D chemical kinetic methodology and in-house codes.
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Simmons, Benjamin M., i Patrick C. Murphy. "Aero-Propulsive Modeling for Tilt-Wing, Distributed Propulsion Aircraft Using Wind Tunnel Data". Journal of Aircraft, 2.03.2022, 1–17. http://dx.doi.org/10.2514/1.c036351.
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Lee, Sang-Don, i Chang-Hun Lee. "Multi-phase and dual aero/propulsive rocket landing guidance using successive convex programming". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, 10.11.2022, 095441002211383. http://dx.doi.org/10.1177/09544100221138350.
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This paper aims to suggest a new landing guidance algorithm for reusable launch vehicles (RLVs) to enable generation of fuel-efficient trajectories based on successive convex programming. To this end, a dual aero/propulsive landing guidance problem is first formulated to fully exploit the additional moment generated by the aerodynamic control to reduce the propulsion demand required for attitude control. As the result of the aerodynamic landing phase could greatly affect the fuel-optimal trajectory during the vertical landing phase, the formulation is further extended to the multi-phase optimal guidance problem using state-triggered constraints. The proposed guidance strategy is then obtained by solving the formulated optimal control problem based on the successive convex optimization framework using an interior point method The main contribution of this study lies in forming new RLV landing guidance problems to get an optimal trajectory and transforming the corresponding nonconvex problem into a convex optimization problem by introducing appropriate combinations for convexification techniques. Additionally, this paper introduces several practical constraints, such as the maximum slew rate of aerodynamic control fins and nozzle angles, which are not considered in previous works. In this paper, the performance of the proposed method with the potential for online computation is investigated through numerical simulations.
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Moirou, N. G. M., N. E. Mutangara i D. S. Sanders. "Fundamental considerations in the design and performance assessment of propulsive fuselage aircraft concepts". Aeronautical Journal, 28.11.2024, 1–26. http://dx.doi.org/10.1017/aer.2024.124.
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Abstract Propulsive fuselage aircraft complement the two under-wing turbofans of current aircraft with an embedded propulsion system within the airframe to ingest the energy-rich fuselage boundary layer. The key design features of this embedding are examined and related to an aero-propulsive performance assessment undertaken in the absolute reference frame which is believed to best evaluate these effects with intuitive physics-based interpretations. First, this study completes previous investigations on the potential for energy recovery for different fuselage slenderness ratios to characterise the aerodynamics sensitivity to morphed fuselage-tail design changes and potential performance before integrating fully circumferential propulsors. Its installation design space is then explored with macro design parameters (position, size and operating conditions) where an optimum suggests up to 11% fuel savings during cruise and up to 16% when introducing compact nacelles and re-scaling of the under-wing turbofans. Overall, this work provides valuable insights for designers and aerodynamicists on the potential performance of their concepts to meet the environmental targets of future aircraft.
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Goulos, Ioannis, John Otter, Tomasz Stankowski, David MacManus, Nicholas Grech i Christopher Sheaf. "Aerodynamic Design of Separate-Jet Exhausts for Future Civil Aero-engines—Part II: Design Space Exploration, Surrogate Modeling, and Optimization". Journal of Engineering for Gas Turbines and Power 138, nr 8 (15.03.2016). http://dx.doi.org/10.1115/1.4032652.
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The aerodynamic performance of the bypass exhaust system is key to the success of future civil turbofan engines. This is due to current design trends in civil aviation dictating continuous improvement in propulsive efficiency by reducing specific thrust and increasing bypass ratio (BPR). This paper aims to develop an integrated framework targeting the automatic design optimization of separate-jet exhaust systems for future aero-engine architectures. The core method of the proposed approach is based on a standalone exhaust design tool comprising modules for cycle analysis, geometry parameterization, mesh generation, and Reynolds-averaged Navier–Stokes (RANS) flow solution. A comprehensive optimization strategy has been structured comprising design space exploration (DSE), response surface modeling (RSM) algorithms, as well as state-of-the-art global/genetic optimization methods. The overall framework has been deployed to optimize the aerodynamic design of two civil aero-engines with separate-jet exhausts, representative of current and future engine architectures, respectively. A set of optimum exhaust designs have been obtained for each investigated engine and subsequently compared against their reciprocal baselines established using the current industry practice in terms of exhaust design. The obtained results indicate that the optimization could lead to designs with significant increase in net propulsive force, compared to their respective notional baselines. It is shown that the developed approach is implicitly able to identify and mitigate undesirable flow-features that may compromise the aerodynamic performance of the exhaust system. The proposed method enables the aerodynamic design of optimum separate-jet exhaust systems for a user-specified engine cycle, using only a limited set of standard nozzle design variables. Furthermore, it enables to quantify, correlate, and understand the aerodynamic behavior of any separate-jet exhaust system for any specified engine architecture. Hence, the overall framework constitutes an enabling technology toward the design of optimally configured exhaust systems, consequently leading to increased overall engine thrust and reduced specific fuel consumption (SFC).
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Hoogreef, Maurice F. M., i Johannes S. E. Soikkeli. "Flight dynamics and control assessment for differential thrust aircraft in engine inoperative conditions including aero-propulsive effects". CEAS Aeronautical Journal, 27.06.2022. http://dx.doi.org/10.1007/s13272-022-00591-5.
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AbstractDifferential thrust can be used for directional control on distributed electric propulsion aircraft. This paper presents an assessment of flight dynamics and control under engine inoperative conditions at minimum control speed for a typical distributed propulsion aircraft employing differential thrust. A methodology consisting of an aerodynamic data acquisition module and a non-linear six-degrees-of-freedom flight dynamics model is proposed. Directional control is achieved using a controller to generate a yaw command, which is distributed to the propulsors through a thrust mapping approach. A modified version of the NASA X-57 aircraft is selected for case studies, where the engine inoperative condition is considered to impact the three leftmost propulsors during climb at minimum control speed. The objective also includes the assessment of the impact of the aero-propulsive coupling for such an aircraft during a failure case. Results show that during the recovery manoeuvre, the aircraft experiences a 78% reduction in total thrust and 30% reduction in total lift caused by the aggressive yaw control effort required to control the heading of the aircraft. Consequently, the powered-stall speed is increased, and the aircraft temporarily loses altitude during the recovery manoeuvre. Differential thrust provides sufficient yaw authority during the engine inoperative condition, and is, therefore, seen to potentially replace the functionality of the rudder for the climb condition that was studied. Additionally, reduction of the vertical tail area was explored and seen to be possible if the response time of the system is low enough. For the studied configuration, this required a response within 400 ms for reduced vertical tail areas.
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Kavvalos, Mavroudis, Rainer Schnell, Maximilian Mennicken, Marco Trost i Konstantinos G. Kyprianidis. "On the Performance of Variable-Geometry Ducted E-Fans". Journal of Engineering for Gas Turbines and Power, 29.07.2024, 1–13. http://dx.doi.org/10.1115/1.4066074.
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Abstract Electrically-driven ducted fans (e-fans), either underwing-mounted or located at the aft-fuselage, can potentially improve the system overall efficiency in hybrid-electric propulsion architectures by increasing their thrust share over the thrust generated by the main engines. However, the low design pressure ratio of such e-fans make them prone to operability issues at off-design conditions, i.e. take-off, where nozzle pressure ratio is close or below the critical value. This paper investigates the operational limitations of such e-fans, proving the necessity of variable geometry. A component zooming approach is deployed by integrating a streamline curvature method within an aero-engine performance tool to investigate the e-fan installed performance and operability. The concepts of variable pitch fan (VPF) and variable area nozzle (VAN) are systematically explored to quantify any performance benefits, while the unavoidable added-weight challenges due to variable geometry are taken into account. Although e-fans with low design pressure ratio (PR) are more susceptible to operability issues compared to higher PR e-fans, the former show improved overall efficiency levels, mainly dominated by propulsive efficiency. It is found that variable geometry not only tackles operability but it can improve the off-design overall efficiency of e-fans even more. VPF mostly affects the component efficiency by reshaping the e-fan performance maps, while VAN has a greater impact on propulsive efficiency by moving the operating points.
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Qin, Jiachen, Zhou Zhou, Guowei Yang, Zhuang Shao i Jia Zong. "Aero-Propulsive Coupling Modeling and Dynamic Stability Analysis of Distributed Electric Propulsion Tandem-Wing UAV with Rapid Ascent Capability". Aerospace Science and Technology, lipiec 2024, 109406. http://dx.doi.org/10.1016/j.ast.2024.109406.
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Simmons, Benjamin M. "System Identification Approach for eVTOL Aircraft Demonstrated Using Simulated Flight Data". Journal of Aircraft, 1.02.2023, 1–16. http://dx.doi.org/10.2514/1.c036896.
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This paper describes a system identification method for electric vertical takeoff and landing (eVTOL) aircraft. The approach merges fixed-wing and rotary-wing modeling techniques with new strategies to develop a modeling method for eVTOL vehicles using flight-test data. The eVTOL aircraft system identification approach is demonstrated through application to the NASA Langley Aerodrome No. 8 tandem tilt-wing, distributed electric propulsion aircraft using a high-fidelity flight dynamics simulation. Orthogonal phase-optimized multisine inputs are applied to each control surface and propulsor at numerous flight conditions throughout the flight envelope to collect informative flight data. An aero-propulsive model is identified at each flight condition using the equation-error method in the frequency domain. The local model parameters are then blended to create a global model across the nominal flight envelope. The identified models are shown to provide a good fit to modeling data with good prediction capability. The methodology is developed with a discussion of unique eVTOL vehicle aerodynamic characteristics and practical strategies intended to inform future flight-based system identification efforts for eVTOL aircraft.
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Simmons, Benjamin M., James L. Gresham i Craig A. Woolsey. "Flight-Test System Identification Techniques and Applications for Small, Low-Cost, Fixed-Wing Aircraft". Journal of Aircraft, 24.06.2023, 1–19. http://dx.doi.org/10.2514/1.c037260.
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This paper provides an overview of flight-test system identification methods applied in the Virginia Tech Nonlinear Systems Laboratory that focus on modeling small, inexpensive, fixed-wing aircraft controlled by a ground-based pilot. The general aircraft system identification approach is outlined with details provided on the flight-test facilities, experiment design methods, instrumentation systems, flight-test operations, data processing techniques, and model identification methods enabling small aircraft flight dynamics model development. Specific small aircraft system identification challenges are overcome, including low-cost control surface servo-actuators and instrumentation systems, as well as a greater sensitivity to atmospheric disturbances and limited piloting cues. Four recent system identification research advancements using the general system identification process are featured, including application of uncorrelated pilot inputs for remotely piloted aircraft, aero-propulsive model development for propeller aircraft, spin aerodynamic model development, and nonlinear dynamic modeling without mass properties information. Although this paper provides a summary of several research efforts, the core system identification approach is presented with sufficient detail to allow the methods to be readily adapted to other research efforts leveraging small, low-cost aircraft.
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Carnevale, Mauro, Feng Wang, Anthony B. Parry, Jeffrey S. Green i Luca di Mare. "Fan Similarity Model for the Fan–Intake Interaction Problem". Journal of Engineering for Gas Turbines and Power 140, nr 5 (19.12.2017). http://dx.doi.org/10.1115/1.4038247.
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Very high bypass ratio turbofans with large fan tip diameter are an effective way of improving the propulsive efficiency of civil aero-engines. Such engines, however, require larger and heavier nacelles, which partially offset any gains in specific fuel consumptions. This drawback can be mitigated by adopting thinner walls for the nacelle and by shortening the intake section. This binds the success of very high bypass ratio technologies to the problem of designing an intake with thin lips and short diffuser section, which is well matched to a low speed fan. Consequently, the prediction of the mutual influence between the fan and the intake flow represents a crucial step in the design process. Considerable effort has been devoted in recent years to the study of models for the effects of the fan on the lip stall characteristics and the operability of the whole installation. The study of such models is motivated by the wish to avoid the costs incurred by full, three-dimensional (3D) computational fluid dynamics (CFD) computations. The present contribution documents a fan model for fan–intake computations based on the solution of the double linearization problem for unsteady, transonic flow past a cascade of aerofoils with finite mean load. The computation of the flow in the intake is reduced to a steady problem, whereas the computation of the flow in the fan is reduced to one steady problem and a set of solutions of the linearized model in the frequency domain. The nature of the approximations introduced in the fan representation is such that numerical solutions can be computed inexpensively, while the main feature of the flow in the fan passage, namely the shock system and an approximation of the unsteady flow encountered by the fan are retained. The model is applied to a well-documented test case and compares favorably with much more expensive 3D, time-domain computations.
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Perullo, Christopher A., Jimmy C. M. Tai i Dimitri N. Mavris. "Effects of Advanced Engine Technology on Open Rotor Cycle Selection and Performance". Journal of Engineering for Gas Turbines and Power 135, nr 7 (12.06.2013). http://dx.doi.org/10.1115/1.4024019.
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Recent increases in fuel prices and increased focus on aviation's environmental impacts have reignited focus on the open rotor engine concept. This type of architecture was extensively investigated in previous decades but was not pursued through to commercialization due to relatively high noise levels and a sudden, sharp decrease in fuel prices. More recent increases in fuel prices and increased government pressure from taxing carbon-dioxide production mean the open rotor is once again being investigated as a viable concept. Advances in aero-acoustic design tools have allowed industry and academia to re-investigate the open rotor with an increased emphasis on noise reduction while retaining the fuel burn benefits due to the increased propulsive efficiency. Recent research with conceptual level multidisciplinary considerations of the open rotor has been performed (Bellocq et al., 2010, “Advanced Open Rotor Performance Modeling For Multidisciplinary Optimization Assessments,” Paper No. GT2010-2963), but there remains a need for a holistic approach that includes the coupled effects of the engine and airframe on fuel burn, emissions, and noise. Years of research at Georgia Institute of Technology have led to the development of the Environmental Design Space (EDS) (Kirby and Mavris, 2008, “The Environmental Design Space,” Proceedings of the 26th International Congress of the Aeronautical Sciences). EDS serves to capture interdependencies at the conceptual design level of fuel burn, emissions, and noise for conventional and advanced engine and airframe architectures. Recently, leveraging NASA environmentally responsible aviation (ERA) modeling efforts, EDS has been updated to include an open rotor model to capture, in an integrated fashion, the effects of an open rotor on conventional airframe designs. Due to the object oriented nature of EDS, the focus has been on designing modular elements that can be updated as research progresses. A power management scheme has also been developed with the future capability to trade between fuel efficiency and noise using the variable pitch propeller system. Since the original GE open rotor test was performed using a military core, there is interest in seeing the effect of modern core-engine technology on the integrated open rotor performance. This research applies the modular EDS open rotor model in an engine cycle study to investigate the sensitivity of thermal efficiency improvements on open rotor performance, including the effects on weight and vehicle performance. The results are that advances in the core cycle are necessary to enable future bypass ratio growth and the trades between core operating temperatures and size become more significant as bypass ratio continues to increase. A general benefit of a 30% reduction in block fuel is seen on a 737-800 sized aircraft.
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Jeschke, Peter, Wolfgang Koschel, Christian Klumpp i Daniel Weintraub. "Teaching Aero-Engine Performance: From Analytics to Hands-On Exercises Using Gas Turbine Performance Software". Journal of Engineering for Gas Turbines and Power, 19.08.2024, 1–11. http://dx.doi.org/10.1115/1.4066244.
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Abstract In this paper, we present an approach for teaching turbojet engine performance that combines mathematical analysis with the use of performance software to provide students with a comprehensive and in-depth understanding of engine performance and how it is affected by design parameter choices. In the first part, we present the derivation of a universally valid analytical model for turbojet engine cycle design, which is the basis of the propulsion courses at RWTH Aachen University. The analytical model allows for the calculation of specific thrust as well as thermal and propulsive efficiencies as a function of pressure ratios and burner exit temperature. These are all expressed as differentiable functions. Their mathematical extremes form a basis for examining the intricate relationships in turbojet engine design. In the second part, we move from theory to practice. We utilize the GasTurb software, computing turbojet engine cycles for a wide range of cycle design parameters. The analytically derived trends are validated and errors introduced by simplifications are assessed. Differences between the analytical approach and software-based performance simulations of real engines, like temperature-dependent gas properties and secondary air systems, are emphasized and discussed, thus providing a bridge to real-world applications. In summary, this paper describes a two-step approach to teaching turbojet engine design using analytics and performance software. Each approach alone can be used to enrich and extend existing performance courses. Combining the approaches has significant benefits, improving understanding and inspiring students to pursue further research in the field of propulsion.