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Relevant bibliographies by topics / Turbofan engines

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Academic literature on the topic 'Turbofan engines'

Author: Grafiati

Published: 4 June 2021

Last updated: 27 July 2024

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Journal articles on the topic "Turbofan engines"

1

Wilde, G. L. "A New Approach to the Design of the Large Turbofan Power Plant." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 209, no. 2 (April 1995): 85–104. http://dx.doi.org/10.1243/pime_proc_1995_209_277_02.

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The lower direct operating costs of the Big Twin subsonic transports encourage the building of ever larger turbofan engines installed on the wings. The steadily improving reliability of the turbofans and the good safety statistics of twin-engined aircraft over many years encourages this trend. Fuel economy is still the dominant factor in determining the design layout of turbofan engines. It requires the combination of the highest possible thermal efficiency of the gas generator core of the engine with optimum propulsion efficiency of the power plant as a whole in cruise flight, allowing for engine nacelle drag and nacelle to wing interference drag. High thermal efficiency and high propulsion efficiency together, lead to relatively small volume flow rate gas generators and high volume flow rate propulsion fans. The resulting geometrical mismatch between the compressors and turbines of the principal turbomachinery components within the engine, introduces losses that penalize the performance gains expected from theoretical considerations of thermodynamics cycle and component efficiencies alone. The paper presents two possible turbofan design layouts intended to overcome the limitation of current turbofan power plant designs. The aim is to design a power plant with the highest thrust per unit frontal area combined with the highest air miles per gallon in cruise flight.

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Mazzawy, Robert S. "Next Generation of Transport Engines." Mechanical Engineering 132, no. 12 (December 1, 2010): 54. http://dx.doi.org/10.1115/1.2010-dec-6.

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This article discusses the features of very high bypass ratio turbofans and open rotor engines. Each of these engine options has its pros and cons to consider. The very large bypass ratio turbofan engine maintains that the proven capability of containment of blade failures is inherently quieter due to ability to incorporate acoustic treatment in the fan duct and is not subject to high fan tip losses associated with direct exposure to higher cruise level flight speeds. The duct does not come for free, however, and installed weight becomes a primary concern as the increased bypass ratio drives up the engine diameter. Additionally, the fan is subject to higher local airfoil incidence when the fan nozzle un-chokes at low flight speed. The open rotor engine can achieve potentially greater improvements in propulsive efficiency than a turbofan but lacks the containment and noise reduction benefits of a duct. The rotor is also exposed to flight speed, driving up tip losses at today's accepted cruise flight speeds.

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Cheng, Dingding, Lijun Liu, and Zhen Yu. "A novel multivariable nonlinear robust control design for turbofan engines." Transactions of the Institute of Measurement and Control 44, no. 5 (October 1, 2021): 1029–44. http://dx.doi.org/10.1177/01423312211039641.

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Traditional steady-state control methods are applied to turbofan engines operating in the small region near certain operating conditions, which need to switch controllers for operating in the large region and then may lead to instability and performance degradation of the closed-loop system. In this paper, a novel multivariable nonlinear robust control method for turbofan engines is proposed to improve the control performance within the large region. To enlarge the controllable region, a polynomial state-space model describes the nonlinear characteristics of turbofan engines. Based on the analysis of the closed-loop control system, by using the Lyapunov function theorems, a polynomial robust controller is designed to ensure the stability and desired nonlinear control performance of turbofan engines. Compared with the classical PI, mixed sensitivity, and H∞ control, simulation results show that the proposed method has better transient responses, disturbance rejection, and other control performance for the turbofan engine within the large region.

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Jakubowski, Robert. "Study of Bypass Ratio Increasing Possibility for Turbofan Engine and Turbofan with Inter Turbine Burner." Journal of KONES 26, no. 2 (June 1, 2019): 61–68. http://dx.doi.org/10.2478/kones-2019-0033.

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Abstract Current trends in the high bypass ratio turbofan engines development are discussed in the beginning of the paper. Based on this, the state of the art in the contemporary turbofan engines is presented and their change in the last decade is briefly summarized. The main scope of the work is the bypass ratio growth analysis. It is discussed for classical turbofan engine scheme. The next step is presentation of reach this goal by application of an additional combustor located between high and low pressure turbines. The numerical model for fast analysis of bypass ratio grows for both engine kinds are presented. Based on it, the numerical simulation of bypass engine increasing is studied. The assumption to carry out this study is a common core engine. For classical turbofan engine bypass ratio grow is compensated by fan pressure ratio reduction. For inter turbine burner turbofan, bypass grown is compensated by additional energy input into the additional combustor. Presented results are plotted and discussed. The main conclusion is drawing that energy input in to the turbofan aero engine should grow when bypass ratio is growing otherwise the energy should be saved by other engine elements (here fan pressure ratio is decreasing). Presented solution of additional energy input in inter turbine burner allow to eliminate this problem. In studied aspect, this solution not allows to improve engine performance. Specific thrust of such engine grows with bypass ratio rise – this is positive, but specific fuel consumption rise too. Classical turbofan reaches lower specific thrust for higher bypass ratio but its specific fuel consumption is lower too. Specific fuel consumption decreasing is one of the goal set for future aero-engines improvements.

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Avdeev, S. V. "Mathematical model of turbofan engine weight estimation taking into account the engine configuration and size." VESTNIK of Samara University. Aerospace and Mechanical Engineering 20, no. 1 (April 20, 2021): 5–13. http://dx.doi.org/10.18287/2541-7533-2021-20-1-5-13.

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The paper presents a new correlation-regression model of estimating the turbofan engine weight considering the effect of the engines design schemes and dimensions. The purpose of this study was to improve the efficiency of the conceptual design process for aircraft gas turbine engines. Information on 183 modern turbofan engines was gathered using the available sources: publications, official websites, reference books etc. The statistic information included the values of the total engine air flow, the total turbine inlet gas temperature, the overall pressure ratio and the bypass ratio, as well as information on the structural layout of each engine. The engines and the related statistics were classified according to their structural layout and size. Size classification was based on the value of the compressor outlet air flow through the gas generator given by the parameters behind the compressor. Depending on the value of this criterion, the engines were divided into three groups: small-sized, medium-sized gas turbine engines, and large gas turbine engines. In terms of the structural layout, all engines were divided into three groups: turbofan engines without a mixing chamber, engines with a mixing chamber and afterburning turbofan engines. Statistical factors of the improved weight model were found for the respective groups of engines, considering their design and size. The coefficients of the developed model were determined by minimizing the standard deviations. Regression analysis was carried out to assess the quality of the developed model. The relative average error of approximation of the developed model was 8%, the correlation coefficient was 0,99, and the standard deviation was 10,2%. The model was found to be relevant and reliable according to Fisher's test. The obtained model can be used to assess the engine weight at the stage of conceptual design and for its optimization as part of an aircraft.

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Kroeger, Jim. "Large and Small Turbofans." Mechanical Engineering 138, no. 09 (September 1, 2016): 80–82. http://dx.doi.org/10.1115/1.2016-sep-7.

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This article presents a study on common design challenges of large and small turbofans. Turbofan engines powering large transport aircraft have demonstrated much different design objectives than business-jet turbofans including thrust, range, mission type, development cost, unit price, maintainability standards, and production quantities. Prolific use of ‘thermal barrier coating’ has helped turbine designers compensate for the inability to distribute a large quantity of small diameter film holes over the turbine blade surface. The historical trends in overall pressure ratio observed for both large and small turbofans have parallel slopes. Small turbofans lag behind the larger engines due to the miniaturization required for low flowrates characteristic of the smaller engines. These trends are qualitatively demonstrated, showing the growth in both the overall engine pressure ratio and turbine inlet temperature for several decades. It has been noted in this paper that the importance of high-performance impeller designs and intricate turbine blade cooling concepts for very low compressor exit corrected flows has not yet been fully appreciated.

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Cilgin, Mehmet Emin, and Onder Turan. "Entropy Generation Calculation of a Turbofan Engine: A Case of CFM56-7B." International Journal of Turbo & Jet-Engines 35, no. 3 (July 26, 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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Sun, Shuang, Yu Liao, Shuo Ding, Yinte Lei, Song Li, Zhijie Hu, and Hualong Dong. "Analysis of the Application and Benefits of Aircraft Electric Wheel Systems during Taxi and Take-Off." International Transactions on Electrical Energy Systems 2023 (November 18, 2023): 1–13. http://dx.doi.org/10.1155/2023/3118713.

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An electric wheel hybrid power system is designed for driving a large single-aisle passenger aircraft during the take-off and ground taxi phases, which consists of an APU, an energy storage system, and a motor. In the taxi phase, the electric wheel hybrid power system works alone, and the turbofan engine does not work, reducing fuel consumption and pollution emissions. During the take-off rolling phase, the electric wheel hybrid power system and turbofan engine work together to reduce the thrust requirement of the turbofan engine. This article establishes an aircraft kinematic model, hybrid power system model, and a mechanical wheel model. The feasibility of the collaborative work of the electric wheels and the turbofan engines is verified by simulations. By utilizing the established hybrid system of electric motor wheels, the fuel consumption can be reduced, and the emissions of CO, HC, and NOX can also be diminished to varying degrees. The input of motor power leads to lower turbine inlet temperature, thereby enhancing the turbofan engine’s service life by approximately 4.3% and saving operational costs.

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Langston, Lee S. "Not So Simple Machines." Mechanical Engineering 135, no. 01 (January 1, 2013): 30–35. http://dx.doi.org/10.1115/1.2013-jan-3.

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This article talks about evolving technologies in making efficient gears for different auto engines. Gears are integral to a new engine that has the potential to change commercial aviation. Pratt & Whitney’s geared turbofan (GTF) jet engine will have significantly better fuel economy and much quieter operation. The P&W GTF combines existing jet engine technology with the well-established mechanical engineering technology of gears. Due to its high bypass ratio, the geared turbofan engine is 16% more efficient than standard jet engines. A key facility for developing the GTF gearbox has been a specially designed four-square gear test rig at P&W’s Middletown plant. The orientation of the GTF test gearboxes can be adjusted with respect to gravity to simulate different flight conditions. After an extensive program using a four-square rig and a long history of gearbox experience associated with their very popular turboprop gas turbines at Pratt & Whitney Canada, P&W engineers are convinced their new GTF engines will have a bright future.

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Bakhtyar, Aminullah, Ahmad Farzad Faqiri, Noman Tasal, Mahboobullah Mutahar, and Suhrab Sheybani. "Airflow Simulation in a Turbofan Engine: A Study of Flow Behavior." Indian Journal of Production and Thermal Engineering 3, no. 6 (October 30, 2023): 1–5. http://dx.doi.org/10.54105/ijpte.c7905.103623.

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The efficient functioning of modern turbofan engines relies heavily on a deep understanding of airflow dynamics within critical components. This research paper presents a comprehensive investigation into airflow simulation within a turbofan engine, employing advanced computational techniques. The study focuses on flow behavior and makes use of SolidWorks for 3D modeling and ANSYS for simulation. The investigation centers on analyzing key flow parameters such as velocity, pressure, and temperature. The methodology involves creating an accurate 3D model of the turbofan engine excluding the compressor, combustion chamber, and turbine using SolidWorks to capture fine geometry and details. Subsequently, ANSYS is utilized to simulate the airflow within the turbofan engine, simulating realistic conditions and enabling the detailed analysis of flow behavior. The results of this study advance knowledge of turbofan engine technology and lay the groundwork for additional study and advancement in the area of aviation propulsion systems. In response to the evolving requirements of the aviation sector, the knowledge acquired from this research will serve as a priceless asset in the development of engines that are characterized by enhanced dependability, a reduced ecological footprint, and heightened fuel efficiency.

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Dissertations / Theses on the topic "Turbofan engines"

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Joo, Won-Gu. "Intake/engine flowfield coupling in turbofan engines." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319865.

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Lambie, David. "Inlet distortion and turbofan engines." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305300.

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Santos, Gustavo Di Fiore dos. "A methodology for noise prediction of turbofan engines." Instituto Tecnológico de Aeronáutica, 2006. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=291.

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A computional model is developed for prediction of noise emission from na existing or new turbofan engine. This model allows the simulation of noise generation from high bypass ratio turbofan engines, appropriate for use with computational programs for gas turbine performance developed at ITA. Analytical and empirical methods are used for spectrum shape, spectrum level, overall noise and free-field directivity noise. The most significant noise sources in turbofan engines are modeled: fan, compressor, combustion chamber, turbine, jet (separate streams or mixed jet), with corrections for forward speed, atmospheric attenuation, ground reflection, and nacelle acoustic treatment (perforate liners). The procedures for component noise prediction are combined to yield total turbofan engine noise emission, as a funtion of engine operation condition and of observer (distance and directivity angle).

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Pietroniro, Asuka Gabriele. "Modelling coaxial jets relevant to turbofan jet engines." Thesis, KTH, Mekanik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-200909.

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Simulations of subsonic turbulent coaxial hot jets were conducted on two types ofunstructured grids within the framework of STAR-CCM+. The study case is based on atypical airliner turbofan engine model with a core nozzle and a fan nozzle, having a bypassratio of five. The two meshes used are a polyhedral one, suitable for complex surfaces, and atrimmed one mainly made of hexahedral cells. The sensitivity of the study case to variousinputs is attested using second and third order upwind schemes, modelling turbulence with aSST k-omega model. The project proves to be a valid feasibility study for a steady-statesolution on which an aeroacoustic analysis could be based in future works.

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Pietroniro, Asuka Gabrielle. "Modelling coaxial jets relevat to turbofan jet engines." Thesis, KTH, Mekanik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-204020.

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Simulations of subsonic turbulent coaxial hot jets were conducted on two types ofunstructured grids within the framework of STAR-CCM+. The study case is based on atypical airliner turbofan engine model with a core nozzle and a fan nozzle, having a bypassratio of five. The two meshes used are a polyhedral one, suitable for complex surfaces, and atrimmed one mainly made of hexahedral cells. The sensitivity of the study case to variousinputs is attested using second and third order upwind schemes, modelling turbulence with aSST k-omega model. The project proves to be a valid feasibility study for a steady-statesolution on which an aeroacoustic analysis could be based in future works.
Simuleringar av subsoniska turbulenta koaxiala varma flöden genomfördes på två typer avostrukturerade nät inom ramen för STAR-CCM+. Studiefallet är baserat på en modell av enturbofläktmotor för ett typiskt trafikflygplan, med en inre samt yttre dysa och med ett bypassförhållandeav fem. De två beräkningsnät som används är ett polyedriskt nät, lämplig förkomplexa ytor, och ett trimmat nät huvudsakligen uppbyggt av sexsidiga celler. Känslighetenav studiefallet beroende på olika indata intygas med hjälp av andra och tredje ordningens”upwind-schemes”, där turbulensen modelleras med en SST k-omega modell. Projektet visarsig vara en giltig förstudie för en steadystate-lösning på vilken en aeroakustisk analys skullekunna baseras i framtida arbeten.

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Kapekov, Ali. "Development of an innovative cooling concept for turbofan engines." Thesis, KTH, Energiteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-246103.

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This paper is submitted in support of a candidature for the Double Degree in Vehicle Engineering with a specialization in Aerospace between KTH Royal Institute of Technology, Sweden, and Ecole Centrale Lyon, France. The present report emphasizes a research project for current or next generation turbofan engines used in civil aviation, and especially its equipment integration from a thermal management point of view. The cooling and ventilation of such equipment in the core compartment is especially harsh. Its optimization had been considered through a complete analysis described in an exhaustive paper which is only available internally at Airbus or for thesis examiners because of confidentiality issues. Considering only Two-Phase flow heat transfer, the heat pipes are deeply explained in order to familiarize the reader. An achievable heat pipe is modelled help to a 1D simulation software called LMS Imagine.Lab AMESim (Siemens PLM). The modelling is illustrated and correlated with experimental values for commercial heat pipes. Finally two other two-phase flow heat transfer systems are duly noted, with a short description of the theory that led to model adaptation and GUIs development using Matlab.
Det här examensarbetet har genomförts för att uppfylla krav för dubbelexamen inom fordonsteknik med specialisering flyg och rymdteknik på KTH i Sverige och Ecole Centrale Lyon i Frankrike. Rapporten fokuserar på ett forskningsprojekt som behandlar teknologi för hantering av värmeöverföring i nuvarande eller framtida flygmotorer som används inom civil luftfart. Kylningen och ventilationen av flygmotorer och dess integration betraktas som särskilt krävande och komplext. Inom projektet har en optimering med tillhörande analyser har genomförts och resultat av dessa beskrivs i en uttömmande rapport tillgänglig för internt bruk på Airbus. Endast en kortfattad sammanställning presenteras i denna rapport som är tillgänglig för allmänhet. För att läsaren ska bekantas djupare med två-fas värmeöverföring, värmerörsteknologi (”heat pipes”) förklaras utförligt i rapporten. Ett passande värmerör design har tagits fram och modellerats med hjälp av 1D simuleringsverktyg LMS Imagine Lab AMESim från Siemens PLM. Den modellerade värmerör har illustrerats och korrelerats med experimentella värden för kända kommersiella värmerör. Slutligen, ytterligare två två-fas värmeöverföringssystem analyseras och noteras med en kort beskrivning av teorin som ledde till modellanpassning och GUI-utveckling i Matlab programmet.

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Kwan, Pok Wang. "Flow management in heat exchanger installations for intercooled turbofan engines." Thesis, University of Oxford, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.711622.

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Almeida, Odenir de. "Aeroacoustics of dual-stream jets with application to turbofan engines." Instituto Tecnológico de Aeronáutica, 2009. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=805.

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A Computational Aeroacoustics (CAA) and a novel semi-empirical model is developed for predicting the noise generated by the jet flow through dual stream (coaxial) nozzles, as found in modern turbofan engines. The acoustic source model was developed in a 2D and 3D framework, based on the Lilley's Equations, following the traditional MGBK method from NASA Langley Research Center. The semi-empirical model was based on the Four-Source model from the Institute of Sound and Vibration (ISVR). This suite of methodologies provided a mean of investigating the mechanisms of noise generation and propagation of subsonic coaxial jet flows, as well as the noise prediction at different operating conditions. The work done contributed to the development and improvement of a numerical tool for jet noise prediction of dual-stream exhaust systems, commonly employed in turbofan engines. Such research also subsidies the improvement of semi-empirical methods used in the Center of Reference in Gas Turbine (ITA) for the noise prediction of turbofans in all operating conditions.

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Adetifa, Oluwaseun Emmanuel. "Prediction of supersonic fan noise generated by turbofan aircraft engines." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/388030/.

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Prediction of Supersonic Fan Noise Generated by Turbofan Aircraft Engines was focussed on improving the capability of predicting supersonic fan noise from modern high-bypass-ratio turbofan aero-engines. The shift from single core jet engines to highbypass-ratio turbofan engines brought about a reduction in the overall aircraft engine noise principally by reducing the jet-broadband noise. However, this new design meant the size of the fan of a high-bypass-ratio turbofan engine, over subsequent years, has increased in diameter. This increase allowed for the speed of the tips of the fan blades to reach and exceed the speed of sound. At high power engine operation conditions, especially at take-off conditions, the noise levels observed from such engines is very high. A major component of this noise is the supersonic fan noise which is also referred to as buzz-saw noise. Shocks are produced at the fan blade tips at this high power engine operation condition. These shocks propagate upstream, against the inflow, following a helical path dictated by the rotation of the fan. The pressure field produced at the tip of the fan is represented as a series of shock waves and expansion waves. As this pressure field advances, it interacts with the incoming flow and acoustic treatment in the intake duct. The shocks in the pressure field are all unique and are of different amplitudes. This is because the fan blades, although manufactured to tight tolerances, are not perfectly alike. Also, the arrangement of these fan blades on the fan hub will also lead to unavoidable differences among the fan blades. These minute differences are reflected in the amplitudes of the shocks, making each shock slightly different from the others. Shocks in the pressure field propagate with respect to the magnitude of their pressure amplitude. Therefore, the shocks travel at different speeds. In the course of propagation, faster shocks catch up with slower ones, and they merge into a single shock, even as the shocks’ amplitudes are attenuated. The difference in speeds and the interactions among the shocks ensure a transfer of energy among the harmonics of the pressure field. This process is nonlinear; the work in this thesis is focussed on modelling the nonlinear propagation of the shocks pressure pattern. These interactions greatly enhance the lower frequency harmonics of the pressure field shifting the dominance from the blade passage frequency and its harmonics. Further upstream, the dominance of the low frequency harmonics is unmistakable. Subsequently the pressure field is radiated from the aircraft intake duct. The resultant radiated pressure field is that which is perceived by an observer in the far-field. The models presented in this thesis capture the main features of this nonlinear propagation and radiation of the pressure field generated at the fan blade tips, and generates predictions for supersonic fan noise levels in the intake duct and in the far-field. A time domain model named SPRID (Sawtooth Propagation in Rigid Intake Ducts) developed is presented. This model predicts the supersonic fan noise levels in ducts without any acoustic treatment, and has been validated against a benchmark frequency domain nonlinear propagation model (FDNS), and also measured data from a modelscale fan rig test provided by Rolls-Royce PLC. The need to incorporate the effect of acoustic liners in the modelling led to the development of a new model which employs the combined time-frequency domain approach. In this model, the nonlinear propagation of the pressure field is simulated in the time domain, while the acoustic liner effects are implemented in the frequency domain. This model also has been validated with measured data. The combined time-frequency domain prediction method was improved to incorporate more complex features of supersonic fan noise propagation. Features such as the change in duct radius along the duct axis and the consequent change in mean flow speeds, and boundary layer effects on the liner absorption have been included in a more advanced model. The advanced nonlinear model is a more representative model of real aircraft intake duct. Also, a theoretical radiation model (GX-Munt) was utilized to predict supersonic fan noise in the far-field. In this thesis, a whole study of supersonic fan noise, starting from source generation at the fan plane up to the radiation to the farfield is presented. The thesis includes an extensive literature review, research on the generation of a source sawtooth for propagation utilizing measured data, and development of equations for nonlinear propagation in axisymmetric intake ducts. Results of the parametric studies using the advanced nonlinear propagation model reliably show all the effects of nonlinear distortion of the shock waves, variation in intake geometry, flow speeds, and variations in the acoustic liner absorption as a consequence of changes in boundary-layer thickness. Comparisons made against measured data, from modelscale fan rig tests conducted by Rolls-Royce PLC, show good and reasonable agreement. The advanced nonlinear propagation model achieves improved prediction capability for supersonic fan noise.

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Spillere, André Mateus Netto. "Towards optimal design of acoustic liners in turbofan aero-engines." reponame:Repositório Institucional da UFSC, 2017. https://repositorio.ufsc.br/xmlui/handle/123456789/182589.

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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Mecânica, Florianópolis, 2017.
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Motores turbofan são largamente utilizados em aeronaves comerciais e são uma das principais fontes de ruído. O ruído desse motores pode ser dividido em diferentes componentes, sendo que o ruído proveniente do fan é de grande importância no processo de certificação da aeronave. Este é geralmente dominado pela presença de tons e suas harmônicas, tornando desejável utilizar um tratamento acústico com grande atenuação em uma faixa estreita de frequência. Isto é obtido por meio de liners acústicos, que podem ser interpretados como um arranjo de ressonadores de Helmholtz. Tradicionalmente, os liners são caracterizados por meio de sua impedância acústica. Esta abordagem possui várias vantagens: (i) a impedância acústica pode ser estimada por modelos semi-empíricos de baixo custo; (ii) várias técnicas experimentais são reportadas na literatura para extrair a impedância do liner, como os métodos inversos, diretos e técnicas in situ; (iii) o conceito de impedância ótima para dutos pode ser desenvolvida, e portanto o liner pode ser projetado para alcançar a impedância ótima; (iv) a previsão de atenuação sonora em dutos é baseada na impedância acústica do liner. Estes quatro itens são abordados neste trabalho. Primeiramente, modelos semi-empíricos preditivos de liner são analisados e comparados com resultados experimentais. Os modelos são baseados na soma de diversos efeitos e dão uma ideia de quais afetam a impedância acústica do liner. Na sequência, técnicas experimentais são investigadas. O método clássico de acoplamento modal é modificado para incluir um modelo de impedância, resultando em curvas contínuas. Além disso, efeitos de condição de contorno na edução de impedância são considerados, e alternativas à condição de contorno de Ingard-Myers são implementadas. A diferença entre resultados na impedância quando a fonte sonora está a montante ou a jusante da amostra também é discutida. Em seguida, o conceito de impedância ótima para dutos circulares na ausência e presença de escoamento uniforme é apresentado, assim como aplicações para geometria de motores aeronáuticos turbofan. Finalmente, a previsão de atenuação sonora baseada em escoamento uniforme e cisalhante é comparada.
Abstract : Turbofan aero-engines are largely employed in commercial aircraft and are one of the main sources of noise. Engine noise can be divided into several components, and fan noise plays a major role in the aircraft certification process. It is generally dominated by the presence of a tone and its harmonics, making desirable to use an acoustic treatment with large attenuation at a narrow bandwidth. This is accomplished by means of acoustic liners, which can be seen as an array of Helmholtz resonators. Usually, the liner is characterized by its acoustic impedance. This approach has several advantages: (i) the acoustic impedance can be predicted by low-cost semi-empirical models; (ii) many experimental techniques are reported in the literature to extract the liner impedance, such as inverse methods, straightforward methods and in situ techniques; (iii) the concept of optimal impedance for ducts can be developed, and therefore the liner can be designed to achieve the optimal impedance; (iv) the sound attenuation prediction in ducts is based on the liner acoustic impedance. These four items are covered in this work. Firstly, liner prediction semi-empirical models are analysed and compared to experimental results. The models are based on the sum of several effects and give an insight into what alters the liner acoustic impedance. On the following, the experimental techniques are investigated. The classical mode matching method is modified to include an impedance model, resulting in smooth impedance curves. Also, the effect of boundary conditions in the educed impedance is considered, and alternatives to the Ingard-Myers boundary condition are implemented. The difference between upstream and downstream acoustic source positions in the educed impedance is also discussed. Next, the concept of optimal impedance for circular ducts in the absence and presence of mean flow is presented, as well some applications to turbofan aero-engine geometries. Finally, sound attenuation predictions based on uniform and shear flow are compared.

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Books on the topic "Turbofan engines"

1

Richter, Hanz. Advanced Control of Turbofan Engines. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-1171-0.

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Richter, Hanz. Advanced control of turbofan engines. New York, NY: Springer, 2012.

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Meyer, Harold D. Aeroacoustic analysis of turbofan noise generation. Cleveland, Ohio: Lewis Reserch Center, 1996.

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A, Kirchgessner Thomas, and United States. National Aeronautics and Space Administration., eds. Airflow calibration and exhaust pressure temperature survey of an F-404, S/N 215-209, turbofan engine. [Washington, DC]: National Aeronautics and Space Administration, 1987.

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Hang kong wo lun feng shan fa dong ji. [Peking]: Guo fang gong ye chu ban she, 1985.

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Christopher, Snyder, Knip Gerald, and United States. National Aeronautics and Space Administration., eds. Advanced core technology: Key to subsonic propulsion benefits. [Washington, DC]: National Aeronautics and Space Administration, 1989.

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A, Wynosky T., and United States. National Aeronautics and Space Administration., eds. Energy efficient engine program: Advanced turbofan nacelle definition study. [Washington, DC: National Aeronautics and Space Administration, 1985.

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Litt, John. A real-time simulator of a turbofan engine. [Washington, DC]: National Aeronautics and Space Administration, 1989.

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C, DeLaat John, Merrill Walter C, United States. Army Aviation Research and Technology Activity., and United States. National Aeronautics and Space Administration., eds. A real-time simulator of a turbofan engine. [Washington, DC]: National Aeronautics and Space Administration, 1989.

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C, DeLaat John, Merrill Walter C, United States. Army Aviation Research and Technology Activity., and United States. National Aeronautics and Space Administration., eds. A real-time simulator of a turbofan engine. [Washington, DC]: National Aeronautics and Space Administration, 1989.

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Book chapters on the topic "Turbofan engines"

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Greatrix, David R. "Turbofan Engines." In Powered Flight, 233–68. London: Springer London, 2012. http://dx.doi.org/10.1007/978-1-4471-2485-6_7.

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El-Sayed, Ahmed F. "Turbine-Based Engines: Turbojet, Turbofan, and Turboramjet Engines." In Fundamentals of Aircraft and Rocket Propulsion, 403–529. London: Springer London, 2016. http://dx.doi.org/10.1007/978-1-4471-6796-9_6.

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Richter, Hanz. "Sliding Mode Control of Turbofan Engines." In Advanced Control of Turbofan Engines, 111–39. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4614-1171-0_6.

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Richter, Hanz. "Introduction." In Advanced Control of Turbofan Engines, 1–18. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4614-1171-0_1.

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Richter, Hanz. "Engine Models and Simulation Tools." In Advanced Control of Turbofan Engines, 19–33. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4614-1171-0_2.

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Richter, Hanz. "Engine Control by Classical Methods." In Advanced Control of Turbofan Engines, 35–50. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4614-1171-0_3.

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Richter, Hanz. "Engine Control by Robust State Feedback." In Advanced Control of Turbofan Engines, 51–90. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4614-1171-0_4.

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Richter, Hanz. "Gain Scheduling and Adaptation." In Advanced Control of Turbofan Engines, 91–110. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4614-1171-0_5.

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Richter, Hanz. "Engine Limit Management with Linear Regulators." In Advanced Control of Turbofan Engines, 141–76. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4614-1171-0_7.

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Richter, Hanz. "Engine Limit Management with Sliding Modes." In Advanced Control of Turbofan Engines, 177–201. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4614-1171-0_8.

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Conference papers on the topic "Turbofan engines"

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Pakmehr, Mehrdad, Marion Mounier, Nathan Fitzgerald, George Kiwada, James Paduano, Eric Feron, and Alireza Behbahani. "Distributed Control of Turbofan Engines." In 45th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2009. http://dx.doi.org/10.2514/6.2009-5532.

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Luis Fajardo Rodriguez and Ruxandra Mihaela Botez. "Civil turbofan engines thrust generic model." In IECON 2012 - 38th Annual Conference of IEEE Industrial Electronics. IEEE, 2012. http://dx.doi.org/10.1109/iecon.2012.6389521.

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Lin, Ching-Fang, and Jianhua Ge. "H-infinity control for turbofan engines." In Guidance, Navigation, and Control Conference and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1998. http://dx.doi.org/10.2514/6.1998-4296.

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Feng, Zhengping, Jianguo Sun, and Qiuhong Li. "ZP/LTR Control for Turbofan Engines." In ASME Turbo Expo 2000: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/2000-gt-0043.

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Among the control methods which have loop transfer recovery ability, such as the LQG/LTR approach, the design of target feedback loop (TFL) is one important step of the procedure for control system design because the performance of the control system designed is limited by its TFL. However in the LQG/LTR approach, the performance in crossing frequency region of TFL designed by Kalman filter or LQ regulator is undesirable, and this results in poor dynamic performance of the control system. In this paper zero placement (ZP) technique is utilized to design TFL for minimum phase plant. The TFL designed by ZP has two advantages over TFL designed by Kalman filter: (1) It has desirable performance in crossing frequency region; (2) Its transfer function approaches to a diagonal matrix at most under the meaning of least square. Obviously if the TFL is recovered well, then the control system has two corresponding features: good dynamic performance and good decoupling performance. Also the ZP/LTR control for a turbofan engine is studied, and simulation results show that the ZP/LTR control system has superior performance to the LQG/LTR control system.

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Tomita, Jesui´no Takachi, Cleverson Bringhenti, Joa˜o Roberto Barbosa, and Antonio Batista de Jesus. "Nacelle Design for Mixed Turbofan Engines." In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-91212.

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Nacelles are responsible for good engine performance and considerable percentage of total aircraft drag, thus fuel consumption. Energy conservation and cost of fuel, among others, require good nacelle design. CFD calculations of the flow around it are a major design tool to predict shock waves, internal boundary layer in the nacelle forebody, high velocity zones and wake. Commercially available software may be used to calculate and visualize the flow at the most critical parts of the nacelle, allowing design modifications aiming at optimizations. This paper overviews the literature on nacelles, the methodologies involved in the design. A case study is presented for a long duct nacelle design, using an axis-symmetric model. Performance characteristics at important operating conditions are also presented.

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Kurzke, Joachim. "Fundamental Differences Between Conventional and Geared Turbofans." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59745.

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The potential for improving the thermodynamic efficiency of aircraft engines is limited because the aerodynamic quality of the turbomachines has already achieved a very high level. While in the past increasing burner exit temperature did contribute to better cycle efficiency, this is no longer the case with today’s temperatures in the range of 1900...2000K. Increasing the cycle pressure ratio above 40 will yield only a small fuel consumption benefit. Therefore the only way to improve the fuel efficiency of aircraft engines significantly is to increase bypass ratio — which yields higher propulsive efficiency. A purely thermodynamic cycle study shows that specific fuel consumption decreases continuously with increasing bypass ratio. However, thermodynamics alone is a too simplistic view of the problem. A conventional direct drive turbofan of bypass ratio 6 looks very different to an engine with bypass ratio 10. Increasing bypass ratio above 10 makes it attractive to design an engine with a gearbox to separate the fan speed from the other low pressure components. Different rules apply for optimizing turbofans of conventional designs and those with a gearbox. This paper describes various criteria to be considered for optimizing the respective engines and their components. For illustrating the main differences between conventional and geared turbofans it is assumed that an existing core of medium pressure ratio with a two stage high pressure turbine is to be used. The design of the engines is done for takeoff rating because this is the mechanically most challenging condition. For each engine the flow annulus is examined and stress calculations for the disks are performed. The result of the integrated aero-thermodynamic and mechanical study allows a comparison of the fundamental differences between conventional and geared turbofans. At the same bypass ratio there will be no significant difference in specific fuel consumption between the alternative designs. The main difference is in the parts count which is much lower for the geared turbofan than for the conventional engine. However, these parts will be mechanically much more challenging than those of a conventional turbofan. If the bypass ratio is increased significantly above 10, then the geared turbofan becomes more and more attractive and the conventional turbofan design is no longer a real option. The maximum practical bypass ratio for ducted fans depends on the nacelle drag and how the installation problems can be solved.

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Ramdin, Shivan, Wilfried Visser, Juan Regueiro, and Tim Rootliep. "Systematic Approach for Modelling Modern Turbofan Engines." In ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/gt2023-103548.

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Abstract Turbofan engine technology has evolved over several decades resulting in highly efficient and reliable propulsion systems for commercial airliners. Maintenance costs have decreased, but still represent a major part of the overall aircraft operating costs. To further minimize these, engine maintenance needs to be planned timely and strategically. Advanced diagnostics and health monitoring methods are being developed at KLM Engine Services (ES) to improve engine maintenance. For health monitoring, gas path analysis is used which requires accurate engine performance models. The modelling task is complicated further by the reduced number of measured gas path parameters with modern turbofan engines. This paper presents a systematic approach to overcome these complications. An engine model usually comprises of a cycle reference point, representing a design point such as maximum take-off thrust. As a first step, a genetic algorithm is used to determine the set of unknown cycle reference point parameters and component efficiencies best matching a set of known engine measurement data. Additionally, physical relations were used as constraints to compensate for the missing data. Off-design performance is calculated by solving a set of non-linear algebraic equations which depend on the unknown component performance maps. The customary method of deriving the performance maps by scaling similar maps at the cycle reference point only, often suffers from large deviations at off-design conditions. Consequently, these ‘baseline’ maps require corrections across the entire operating envelope. In the second step of the method, genetic algorithms determine the best off-design performance estimations at multiple measured operating points by finding the optimal coefficients of polynomial scaling functions for map parameters such as efficiency, corrected pressure ratio and mass flow. The modelling method has been verified by developing CF6-80C2 and GEnx-1B turbofan engine models using test cell data. The GEnx-1B engine model has subsequently been validated using on-wing operating data. The largest validation error was attained at cruise flight conditions and was found to be equal to 3.9%. The resulting method provides a systematic way to deal with missing data and can be used for developing accurate engine models for better gas path analysis reliability, resulting in more effective engine maintenance.

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Tong, Michael T. "Aero-Engines AI - A Machine-Learning App for Aircraft Engine Concepts Assessment." In ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/gt2023-102024.

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Abstract Effective deployment of machine-learning (ML) models could drive a high level of efficiency in aircraft engine conceptual design. Aero-Engines AI is a user-friendly app that has been created to deploy trained machine-learning (ML) models to assess aircraft engine concepts. It was created using tkinter, a GUI (graphical user interface) module that is built into the standard Python library. Employing tkinter greatly facilitates the sharing of ML application as an executable file which can be run on Windows machines (without the need to have Python or any library installed). The app gets user input for a turbofan design, preprocesses the input data, and deploys trained ML models to predict turbofan thrust specific fuel consumption (TSFC), engine weight, core size, and turbomachinery stage-counts. The ML predictive models were built by employing supervised deep-learning and K-nearest neighbor regression algorithms to study patterns in an existing open-source database of production and research turbofan engines. They were trained, cross-validated, and tested in Keras, an open-source neural networks API (application programming interface) written in Python, with TensorFlow (Google open-source artificial intelligence library) serving as the backend engine. The smooth deployment of these ML models using the app shows that Aero-Engines AI is an easy-to-use and a time-saving tool for aircraft engine design-space exploration during the conceptual design stage. Current version of the app focuses on the performance prediction of conventional turbofans. However, the scope of the app can easily be easily expanded to include other engine types (such as turboshaft and hybrid-electric systems) after their ML models are developed. Overall, the use of a machine-learning app for aircraft engine concept assessment represents a promising area of development in aircraft engine conceptual design.

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Aguilar, Rene, Cesar Celis, and Marcio Pontes. "Numerical Study of the Effects of Confined Airfoils Usage in High Bypass Ratio Turbofan Engines." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-24196.

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Abstract Turbofan engines are the main power plants used in the commercial airline industry. Increasing the bypass ratio (BPR) in turbofan engines enhances their propulsive efficiency and reduces both noise and harmful gas emissions. Over the years the aero engine industry has devoted huge efforts and enormous amounts of money to improve turbofans’ propulsive efficiency through the increase of their BPR. Based on the current technology however, there is a practical limit to how much BPR can be increased before significant penalties associated with increased both engine weight and nacelle drag erode the benefits. This work numerically studies thus the benefits of using confined airfoils in the engine bypass flow region to counteract the turbofan engine weight and alleviate the efforts over the aircraft wing structure. Accordingly, a description of the proposed engine-airfoils arrangement, relative dimensions and airfoils adequate placement inside the engine bypass duct is initially presented. Two different flight conditions, take-off and cruise, are numerically assessed next using computational fluid dynamics (CFD) based approaches to characterize the particular bypass flow behavior. The numerical work includes the study of engine configurations similar to those used in long-range aircraft. A structured multi-domain mesh, in conjunction with both Reynolds-average Navier Stokes (RANS) and steady-state mixing planes approaches, are used in the numerical model utilized. The main results indicate that using confined airfoils produces substantial lift respect to the engine weight. Engine weight reductions of up to 23% are observed because of the use of confined airfoils in the engines bypass ducts.

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Debiasi, Marco, and Dimitri Papamoschou. "Cycle analysis for quieter supersonic turbofan engines." In 37th Joint Propulsion Conference and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2001. http://dx.doi.org/10.2514/6.2001-3749.

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Reports on the topic "Turbofan engines"

1

Dugas, R. M. Effects of Test Cell Recirculation on High-Bypass Turbofan Engines during Simulated Altitude Tests. Fort Belvoir, VA: Defense Technical Information Center, August 1986. http://dx.doi.org/10.21236/ada171418.

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Chippa, Christopher. Sea Level Operation Demonstration of F404-GE-400 Turbofan Engine with JP-5/Bio-Fuel Mixture. Fort Belvoir, VA: Defense Technical Information Center, March 2010. http://dx.doi.org/10.21236/ada517278.

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