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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.
9
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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Wei, Kaixiang. "Turbofan and turbojet engines: Working process and future development." Theoretical and Natural Science 12, no. 1 (November 17, 2023): 114–19. http://dx.doi.org/10.54254/2753-8818/12/20230447.
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This article is based on the fundamental thermodynamics theory to analyze the difference between the turbojet and turbofan engines. The result of this article is that the turbofan engine is suitable for commercial use since it consumes less fuel and has a higher bypass ratio than the turbojet engine. But low bypass ratio engines can serve the military since they have a smaller volume and higher speed, suitable for air combat. The turbojet engine can travel at a supersonic speed since it has extremely high jet flow from the nozzle and much higher fuel consumption, so it is for military use. This article also analyses two cases: i) How the number of fan blades and outlet guide vans affects the noise of the engine produced. ii) When airplanes fly through volcanic ash, how does the ash damage the airplane and the engine? The engineer found that 55 outlet guide vans are better than 37. To prevent airplanes from flying through volcanic ash, satellite weather photos start to show the volcanic ash area.
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Gorji-Bandpy, Mofid, and Mohammadreza Azimi. "TECHNOLOGIES FOR JET NOISE REDUCTION IN TURBOFAN ENGINES." Aviation 16, no. 1 (April 5, 2012): 25–32. http://dx.doi.org/10.3846/16487788.2012.679770.
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Turbofan engines are commonly used for commercial transport due to their advantages of higher performance and lower noise. Jet noise is one of the principal noise sources of turbofan aeroplane engines and remains an acute environmental problem that requires advanced solutions. The ever-increasing demand for quieter engines requires the exploration of alternative techniques that could be used by themselves or in conjunction with existing methods. Significant progress continues to be made with noise reduction for turbofan engines. Analytical and semiempirical models have been developed to investigate the influence of some design tools when they are employed in a multidisciplinary optimisation framework. This paper discusses the major components of jet noise in turbofan engines and presents a review of jet noise reduction technologies.
13
Welch, G. E., S. M. Jones, and D. E. Paxson. "Wave-Rotor-Enhanced Gas Turbine Engines." Journal of Engineering for Gas Turbines and Power 119, no. 2 (April 1, 1997): 469–77. http://dx.doi.org/10.1115/1.2815598.
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The benefits of wave rotor topping in small (300- to 500-kW [400- to 700-hp] class) and intermediate (2000- to 3000-kw [3000- to 4000-hp] class) turboshaft engines, and large (350- to 450-kN [80,000- to 100,000-lbf] class) high-bypass-ratio turbofan engines are evaluated. Wave rotor performance levels are calculated using a one-dimensional design/analysis code. Baseline and wave-rotor-enhanced engine performance levels are obtained from a cycle deck in which the wave rotor is represented as a burner with pressure gain. Wave rotor topping is shown to enhance the specific fuel consumption and specific power of small- and intermediate-sized turboshaft engines significantly. The specific fuel consumption of the wave-rotor-enhanced large turbofan engine can be reduced while it operates at a significantly reduced turbine inlet temperature. The wave-rotor-enhanced engine is shown to behave off-design like a conventional engine. Discussion concerning the impact of the wave rotor/gas turbine engine integration identifies technical challenges.
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Li, Shengyuan. "Development trends and future expectations of jet engine." Applied and Computational Engineering 11, no. 1 (September 25, 2023): 129–36. http://dx.doi.org/10.54254/2755-2721/11/20230221.
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Nowadays, nearly all large commercial aircraft are powered by gas turbine engines. Having been developed for about 80 years of engines applied on commercial aircraft, from low bypass ratio turbojet engines to high bypass ratio turbofan engines since the first turbojet engine was patented in 1930 by Frank Whittle, gas turbine engines still have a high potential to improve the performance. Currently, motor thermodynamic efficiency can still rise in the following decades; composite materials, for instance, gamma titanium aluminum and polymer matrix composites, are becoming widely used in airliner propulsion due to their lightweight and high-temperature capability. Accordingly, environmental issues related to gas emissions have also become vital due to the continued flourishing of commercial airliners. In this paper, the development of gas turbine engines applied on commercial airliners from low bypass ratio turbojet engine "Nene1" to high bypass ratio turbofan engine "GE9X," and the current advancement of jet engines applied will be discussed in order to gain possible improvement on the performance of jet engines. Current conditions and expectations of jet engines will be discussed with specific examples, focusing on efficiency, materials and manufacturing, and environmental issues. In the paper, the engines mentioned are all related to commercial aircraft.
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Buraimah, I. J. "Using modern clustering techniques for parametric fault diagnostics of turbofan engines." Civil Aviation High Technologies 23, no. 6 (December 31, 2020): 20–27. http://dx.doi.org/10.26467/2079-0619-2020-23-6-20-27.
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The 21st century aviation and aerospace technologies have evolved and become more complex and technical. Turbofan jet engines as well as their cousins, the rocket engines (liquid/solid) have gone through several design upgrades and enhancements during the course of their design and exploitation. These technological upgrades have made engines very complex and expensive machines which need constant monitoring during their working phase. As the demand and use of such engines is growing steadily, both in the civilian and military sectors, it becomes necessary to monitor and predict the behavior of parametric data generated by these complex engines during their working phases. In this paper flight parameters such as Exhaust Gas Temperature (EGT), Engine Fan Speeds (N1 and N2), Fuel Flow (FF), Oil Temperature (OT), Oil Pressure (OP), Vibration and others where used to determine engine fault. All turbo fan engines go through several distinctly different working phases: Take-off phase, Cruise phase and Landing phase. Recording generated parametric data during these different phases leads to a massive amount of in-flight data and maintenance reports, which makes the task of designing and developing a fault diagnostic system highly challenging. It becomes imperative to use modern techniques in data analysis that can handle large volumes of generated data and provide clear visual results for determining the technical status of the engine under investigation/monitoring. These modern techniques should be able to give clear and objective assessment of the object under investigation. Cluster analysis methods based on Neural Networks such as c-means, k-means, self-organizing maps and DBSCAN algorithm have been used to build clusters. Differences in cluster groupings/patterns between healthy engine and engine with degraded performance are compared and used as the bases for defining faults. Fault diagnosis plays a crucial role in aircraft engine management. Timely and accurate detection of faults is the foundation on which maintenance turnaround times, operational costs and flight safety are based. The data used in this paper for analysis was obtained from flight data recorder during one flight cycle. The final decision on a fault is taken by an engineer.
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Fan, Qiwei. "Challenges to aviation in the global warming context." Theoretical and Natural Science 25, no. 1 (December 20, 2023): 89–99. http://dx.doi.org/10.54254/2753-8818/25/20240927.
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The aviation sector has undergone substantial growth, leading to a corresponding increase in emissions attributed to this industry. This escalation in emissions has notably contributed to the intensification of global warming. This research provides a comprehensive examination of various prospective solutions to mitigate these emissions. Among the proposed solutions is the adoption of an intercooled turbofan engine. This specific engine type holds the promise of realizing a 3.1% reduction in fuel consumption compared to traditional engines. Furthermore, the incorporation of a recuperator in an intercooled turbofan engine could potentially lead to a significant decrease in fuel consumption by up to 30%, alongside a remarkable 20% improvement in engine efficiency. The discourse also extends to the subject of hydrogen-powered aviation, underscoring its substantial potential in achieving emissions reduction goals. However, the associated challenges, especially those related to hydrogen storage, are also explored in this study. The forthcoming era of jet engine technology may witness the amalgamation of intercooled turbofan engines and hydrogen energy sources as a viable pathway for substantial emissions reduction.
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Aghasharifian Esfahani, Majid, Mohammadmehdi Namazi, Theoklis Nikolaidis, and Soheil Jafari. "Advanced Control Algorithm for FADEC Systems in the Next Generation of Turbofan Engines to Minimize Emission Levels." Mathematics 10, no. 10 (May 23, 2022): 1780. http://dx.doi.org/10.3390/math10101780.
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New propulsion systems in aircrafts must meet strict regulations and emission limitations. The Flightpath 2050 goals set by the Advisory Council for Aviation Research and Innovation in Europe (ACARE) include reductions of 75%, 90%, and 65% in CO2, NOx, and noise, respectively. These goals are not fully satisfied by marginal improvements in gas turbine technology or aircraft design. A novel control design procedure for the next generation of turbofan engines is proposed in this paper to improve Full Authority Digital Engine Control (FADEC) systems and reduce the emission levels to meet the Flightpath 2050 regulations. Hence, an Adaptive Network–based Fuzzy Inference System (ANFIS), nonlinear autoregressive network with exogenous inputs (NARX) techniques, and the block-structure Hammerstein–Wiener approach are used to develop a model for a turbofan engine. The Min–Max control structure is chosen as the most widely used practical control algorithm for gas turbine aero engines. The objective function is considered to minimize the emission level for the engine in a pre-defined maneuver while keeping the engine performance in different aspects. The Genetic Algorithm (GA) is applied to find the optimized control structure. The results confirm the effectiveness of the proposed approach in emission reduction for the next generation of turbofan engines.
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Tuninetti, Víctor, and Héctor Sepúlveda. "Computational Mechanics for Turbofan Engine Blade Containment Testing: Fan Case Design and Blade Impact Dynamics by Finite Element Simulations." Aerospace 11, no. 5 (April 24, 2024): 333. http://dx.doi.org/10.3390/aerospace11050333.
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The harsh environment during airplane take-off and flights with complex operating conditions require a high dynamic and impact resistance capability of airplane engines. The design, development, and performance evaluation of new turbofan engines are generally performed through numerical simulations before a full-scale model or prototype experiment for certification. Simulations of fan blade containment tests can reduce trial–error testing and are currently the most convenient and inexpensive alternative for design; however, certification failure is always a risk if the calibration of material models is not correctly applied. This work presents a three-dimensional computational model of a turbofan for designing new engines that meet the certification requirements under the blade containment test. Two calibrated Johnson–Cook plasticity and damage laws for Ti64 are assessed in a simulation of a turbofan blade containment test, demonstrating the ability of the models to be used in the safe design of aircraft engine components subjected to dynamic impact loads with large deformations and adequate damage tolerance.
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Mawid, M. A., T. W. Park, B. Sekar, and C. Arana. "Application of Pulse Detonation Combustion to Turbofan Engines." Journal of Engineering for Gas Turbines and Power 125, no. 1 (December 27, 2002): 270–83. http://dx.doi.org/10.1115/1.1494098.
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The potential performance gain of utilizing pulse detonation combustion in the bypass duct of a turbofan engine for possible elimination of the traditional afterburner was investigated in this study. A pulse detonation turbofan engine concept without an afterburner was studied and its performance was assessed. The thrust, specific fuel consumption (SFC), and specific thrust of a conventional turbofan with an afterburner and the new pulse detonation turbofan engine concept were calculated and compared. The pulse detonation device performance in the bypass duct was obtained by using multidimensional CFD analysis. The results showed that significant performance gains can be obtained by using the pulse detonation turbofan engine concept as compared to the conventional afterburning turbofan engine. In particular, it was demonstrated that for a pulse detonation bypass duct operating at a frequency of 100 Hz and higher, the thrust and specific thrust of a pulse-detonation turbofan engine can nearly be twice as much as those of the conventional afterburning turbofan engine. SFC was also shown to be reduced. The effects of fuel-air mixture equivalence ratio and partial filling on performance were also predicted. However, the interaction between pulse detonation combustion in the bypass duct and the engine fan, for potential fan stall, and engine nozzle have not been investigated in this study.
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Liu, Xiaofeng, Liuqi Xiong, Yiming Zhang, and Chenshuang Luo. "Remaining Useful Life Prediction for Turbofan Engine Using SAE-TCN Model." Aerospace 10, no. 8 (August 16, 2023): 715. http://dx.doi.org/10.3390/aerospace10080715.
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Turbofan engines are known as the heart of the aircraft. The turbofan’s health state determines the aircraft’s operational status. Therefore, the equipment monitoring and maintenance of the engine is an important part of ensuring the healthy and stable operation of the aircraft, and it is vital to monitor the remaining useful life (RUL) of the engine. The monitored data of turbofan engines have high dimensions and a long time span, which cause difficulties in predicting the remaining useful life of the engine. This paper proposes a residual life prediction model based on Autoencoder and a Temporal Convolutional Network (TCN). Among them, Autoencoder is used to reduce the dimension of the data and extract features from the engine monitoring data. The TCN network is trained on the obtained low-dimensional data to predict the remaining useful life. The model mentioned in this article is verified on the NASA public data set (C-MAPSS) and compared with common machine learning methods and other deep neural networks. The SAE-TCN model achieved better scores on the FD001 independent testing data set with an RMSE of 18.01 and a score of 161. The average relative error of the model relative to other common learning models is 0.9499 in RMSE and 0.2656 in Scoring Function. The experimental results show that the model proposed in this paper performs the best in the evaluation, and this conclusion has important implications for engine health.
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Rosell, Daniel, and Tomas Grönstedt. "Design Considerations of Low Bypass Ratio Mixed Flow Turbofan Engines with Large Power Extraction." Fluids 7, no. 1 (January 1, 2022): 21. http://dx.doi.org/10.3390/fluids7010021.
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The possibility of extracting large amounts of electrical power from turbofan engines is becoming increasingly desirable from an aircraft perspective. The power consumption of a future fighter aircraft is expected to be much higher than today’s fighter aircraft. Previous work in this area has concentrated on the study of power extraction for high bypass ratio engines. This motivates a thorough investigation of the potential and limitations with regards to performance of a low bypass ratio mixed flow turbofan engine. A low bypass ratio mixed flow turbofan engine was modeled, and key parts of a fighter mission were simulated. The investigation shows how power extraction from the high-pressure turbine affects performance of a military engine in different parts of a mission within the flight envelope. An important conclusion from the analysis is that large amounts of power can be extracted from the turbofan engine at high power settings without causing too much penalty on thrust and specific fuel consumption, if specific operating conditions are fulfilled. If the engine is operating (i) at, or near its maximum overall pressure ratio but (ii) further away from its maximum turbine inlet temperature limit, the detrimental effect of power extraction on engine thrust and thrust specific fuel consumption will be limited. On the other hand, if the engine is already operating at its maximum turbine inlet temperature, power extraction from the high-pressure shaft will result in a considerable thrust reduction. The results presented will support the analysis and interpretation of fighter mission optimization and cycle design for future fighter engines aimed for large power extraction. The results are also important with regards to aircraft design, or more specifically, in deciding on the best energy source for power consumers of the aircraft.
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Rolt, Andrew, Vishal Sethi, Florian Jacob, Joshua Sebastiampillai, Carlos Xisto, Tomas Grönstedt, and Lorenzo Raffaelli. "Scale effects on conventional and intercooled turbofan engine performance." Aeronautical Journal 121, no. 1242 (June 8, 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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Baig, M. F., and N. Sayeed. "Model-based reasoning for fault diagnosis of twin-spool turbofans." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 212, no. 2 (February 1, 1998): 109–16. http://dx.doi.org/10.1243/0954410981532171.
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A simplified rule-based expert system can be of great use to maintenance engineers involved in on-line health monitoring of aero-engines. The development of a rule base has been done on the following lines: 1 A design and off-design mathematical model of the turbofan has been developed. 2 Healthy and fault-implanted engines have been run at various off-design conditions to see the effect of faults on certain aero-thermodynamic performance parameters, with appropriate selection of independent parameter(s). 3 From these calculated values, fault matrices have been developed for sea-level static conditions taking the net thrust as an independent parameter. 4 From these fault matrices, rules have been developed which form the knowledge core of the expert shell. These rules have been developed for Garrett TFE 731-2, a moderate bypass and overall pressure ratio, generic twin-spool turbofan and so the package (off-design code plus expert system) can serve as a pedagogical tool for training of engineers in the aero-engine industry and academic institutions.
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Кислов, Олег Владимирович, and Михаил Анатольевич Шевченко. "ОСОБЕННОСТИ РАСЧЕТА И РЕГУЛИРОВАНИЯ ДВУХКОНТУРНОГО ТУРБОРЕАКТИВНОГО ДВИГАТЕЛЯ С ФОРСАЖНОЙ КАМЕРОЙ СГОРАНИЯ В НАРУЖНОМ КОНТУРЕ НА ПРЯМОТОЧНЫХ РЕЖИМАХ РАБОТЫ." Aerospace technic and technology, no. 6 (November 27, 2020): 15–23. http://dx.doi.org/10.32620/aktt.2020.6.02.
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A promising direction in aviation is the creation of anaircraft for supersonic cruise speeds (Mach 3...4). It is known that ramjet engines are more preferable for Mach numbers larger 3. However, they do not have starting thrust and uneconomical at subsonic flight speeds. At the same time, at subsonic flight speeds, turbofan engines are the most expedient. The combination of the positive properties of turbofan engines at subsonic speeds and a ramjet engines at supersonic speeds is possible by using duct-burning turbofan engine, which can operate at the ramjet mode with the blocked gas turbine duct at supersonic flight conditions. At this mode, duct-burning turbofan engine turns into ramjet engine, which, however, has special features due to the presence of fan in front of the combustion chamber, which operates in turbine mode or in zero power mode and also because of the outlet jet, which has annular shape, flows out from the duct causes the appearance of bottom drag. The presence of bottom drag requires both the development of a mathematical model for its calculation and taking into account its influence on the choice of the control law for the nozzle outlet area. The article presents a mathematical model of the working process of duct-burning turbofan engine at ramjet mode, taking into account the presence of fan in the flow path and bottom drug. Using the developed mathematical model, the regularities of changes in the internal and effective thrust, as well as the specific fuel consumption, depending on the relative fuel consumption and the critical section of the nozzle at a given altitude and flight speed are established. The critical section of the nozzle is the main regulating factor, and the relative fuel consumption is related to the main regulating factor - the fuel consumption. These patterns are useful for choosing a control program.There is such a combination of regulating factors whichprovides two extremes in the regularities of trust and specific fuel consumption changes: the mode of minimum specific fuel consumption and the mode of maximum thrust. In addition, the influence of gas underexpansion in the nozzle on the thrust-economic parameters of the engine and the required area of the nozzle outlet section were estimated. The obtained regularities are advisable to use when engine control program is chosen.
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Suh, Young B. "Takeoff characteristics of turbofan engines." Journal of Aircraft 27, no. 5 (May 1990): 458–61. http://dx.doi.org/10.2514/3.25299.
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Ulitenko, Yurii, Maryna Minenok, and Igor Kravchenko. "Аналіз впливу місця впорскування води на характеристики турбореактивного двоконтурного двигуна з форсажною камерою згоряння." Aerospace Technic and Technology, no. 4sup2 (August 24, 2023): 35–42. http://dx.doi.org/10.32620/aktt.2023.4sup2.04.
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An important direction for the development of high-speed aircraft is the expansion of the range of operation of aircraft engines as part of their power plants. Currently, the range of operation of aircraft engines in terms of altitude and flight speed is limited by the ability of construction materials to withstand the temperature of the working body. Therefore, to expand the range of operation, it is necessary to either change the construction materials or use technologies that involve cooling the working body. The water injection system in a turbofan engine with an afterburner allows cooling of the working body without significant interference with the structural profile of the engine, which significantly saves design time and development cost. In addition, water injection has long been used for a short-term increase in engine thrust, which is an additional advantage of using this system. The choice of the place of water injection into the engine tract has a great influence on its characteristics and on the ability of the high-speed aircraft to perform the assigned tasks. Therefore, the design of the engine must take place with an understanding of the intended purpose of the high-speed aircraft. This article analyzes the influence of the place of water injection on the characteristics of a turbofan engine with an afterburner. I will consider water injection at the inlet to the fan and at the inlet to the high-pressure compressor. The influence of injection site and flight conditions on water consumption is shown. Operating conditions were found in which it is impossible to use a turbofan engine with an afterburner due to restrictions not related to the temperature of the working fluid. The results of calculations regarding the influence of the water injection site on the main thermodynamic parameters and traction characteristics of the engine are given. The application of the obtained results will increase the thermodynamic efficiency and extend the operating range of two-circuit turbofan engines with afterburners using modern materials. The results of this work will also make it possible to shorten the period of development of competitive engines for high-speed aircraft through a targeted search for their rational thermodynamic and structural-geometric outline.
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Zhou, Zeyang, and Jun Huang. "Study of the Radar Cross-Section of Turbofan Engine with Biaxial Multirotor Based on Dynamic Scattering Method." Energies 13, no. 21 (November 5, 2020): 5802. http://dx.doi.org/10.3390/en13215802.
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With the continuous advancement of rotor dynamic electromagnetic scattering research, the radar cross-section (RCS) of turbofan engines has attracted more and more attention. In order to solve the electromagnetic scattering characteristics of a biaxial multirotor turbofan engine, a dynamic scattering method (DSM) based on dynamic simulation and grid transformation is presented, where the static RCS of the engine and its components is calculated by physical optics and physical theory of diffraction. The results show that the electromagnetic scattering of the engine is periodic when the engine is working stably, while the rotors such as fans and turbines are the main factors affecting the dynamic electromagnetic scattering and the ducts greatly increase the overall RCS level of the engine. The proposed DSM is effective and efficient for studying the dynamic electromagnetic scattering characteristic of the turbofan engine.
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Liu, Hangyu. "Current Status of Jet Engines and Their future." Highlights in Science, Engineering and Technology 43 (April 14, 2023): 280–86. http://dx.doi.org/10.54097/hset.v43i.7430.
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Jet engines have important application value and status in the aerospace field, which directly affects the development of aircraft and spacecraft. This year, jet engines have gradually become the focus and hotspot of scholars at home and abroad. Through the method of literature comparison and analysis, this paper focuses on analysing two common jet engines, namely turbofan engine and pulse jet engine, and makes a detailed analysis and comparison of their working principles and applications; for the future development of parts, three-dimensional (3D) printing technology as an example, the use of different kinds of 3D printing, electron beam melting and selective laser melting to print jet engine parts and how to reduce errors is studied, and various techniques for improving high temperature parts are analysed., and looked forward to the future development trend of jet engines and put forward their own views. The research work in this paper will promote the development of jet engine and provide reference for engineers and technicians.
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Awang Saifudin, Awang Raisudin, and Nurul Musfirah Mazlan. "Computational Exploration of a Two-Spool High Bypass Turbofan Engine's Component Deterioration Effects on Engine Performance." Applied Mechanics and Materials 629 (October 2014): 104–8. http://dx.doi.org/10.4028/www.scientific.net/amm.629.104.
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Aircraft engines are exposed to degradation due to several factors such as environmental air pollution, fuel content and ageing or degradation of engine’s components, which are experienced within specified time. While the turbofan in operation, its components deteriorate and consequently affect its performance. This study is aimed to computationally investigate the effect of components degradation on engine performance. A high bypass turbofan engine operated at cruise is selected for this evaluation and the simulation was performed using the Gas Turbine Simulation Program (GSP). The affected components considered are turbines and compressors with deterioration rate ranging from 0% to 5%. The effect of selected deterioration rate on engine thrust and thrust specific fuel consumption (TSFC) is studied. Results obtained show an agreement with literature where reduction in engine thrust and TSFC are observed. Turbine’s fouling has been found to be more severe than erosion in terms of power and efficiency losses. However, in terms of the overall performance, the erosion effect is more severe than fouling.
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Liu, Xue, Jian Ma, and Dengwei Song. "Personalized Transfer Learning Framework for Remaining Useful Life Prediction Using Adaptive Deconstruction and Dynamic Weight Informer." Axioms 12, no. 10 (October 12, 2023): 963. http://dx.doi.org/10.3390/axioms12100963.
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The precise remaining useful life (RUL) prediction of turbofan engines benefits maintenance decisions. The training data quantity and quality are crucial for effective prediction modeling and accuracy improvement. However, the performance degradation process of the same type of turbofan engine usually exhibits different trajectories because of engines’ differences in degradation degrees, degradation rates, and initial health states. In addition, the initial part of the trajectory is a stationary health stage, which contains very little information on degradation and is not helpful for modeling. Considering the differential degradation characteristics and the requirement for accurate prediction modeling of the same type of turbofan engines with individual differences, we specifically propose a personalized transfer learning framework for RUL prediction by answering three key questions: when, what, and how to transfer in prediction modeling. The framework tries to maximumly utilize multi-source-domain data (samples of the same type of engines that run to failure) to improve the training data quantity and quality. Firstly, a transfer time identification method based on a dual-baseline performance assessment and the Wasserstein distance is designed to eliminate the worthless part of a trajectory for transfer and prediction modeling. Then, the transferability of each sample in the multi-source domain is measured by an approach, named the time-lag ensemble distance measurement, and then the source domain is ranked and adaptively deconstructed into two parts according to transferability. Ultimately, a new training loss function considering the transferability of the weighted multi-source-domain data and a two-stage transfer learning scheme is introduced into an informer-based RUL prediction model, which has a great advantage for long-time-series prediction. The simulation data of 100 of the same type of turbofan engine with individual differences and five comparison experiments validate the effectiveness and accuracy of the proposed method.
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Goulos, I., J. Otter, T. Stankowski, D. Macmanus, N. Grech, and C. Sheaf. "Design optimisation of separate-jet exhausts for the next generation of civil aero-engines." Aeronautical Journal 122, no. 1256 (September 19, 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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Langston, Lee S. "Gears Steer New Engine Designs." Mechanical Engineering 139, no. 09 (September 1, 2017): 54–55. http://dx.doi.org/10.1115/1.2017-sep-7.
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This article reviews the development of geared turbofan (GTF) engines. GTF engines have a hub-mounted epicyclic gearbox that drives the front-mounted fan at lower rotational speeds than the engine turbine section that powers the fan. The turbine driving the fan is most efficient at high-rotational speeds. The fan operates most efficiently and creates less noise at lower rpm. The operating gear reduction ratio also permits increasing the engine’s bypass ratio with larger fans. Gear trains are one of the oldest known machines, and none is more closely identified by the general public with the profession of mechanical engineering. Pratt & Whitney is in production of their first generation of GTF engines in the 18,000–30,000 lbt range, which power twin engine single-aisle, narrow body 70–200 passenger aircraft. The GTF combines existing jet engine technology with the well-established mechanical engineering technology of gears.
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Xu, Wenhao, Muxuan Pan, Jiakun Qin, and Jinquan Huang. "Reference and Limit Governors for Limit Protection of Turbofan Engines." Energies 12, no. 14 (July 21, 2019): 2803. http://dx.doi.org/10.3390/en12142803.
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This paper proposes a novel architecture of limit protection including the references governors and limit governors and applies this architecture to limit protection in turbofan engines. References governors are designed as add-on schemes to a pre-stability engine control system that modifies reference commands to avoid constraints violation. Limit governors are proposed as an assistant part for references governors adjusting constraints to prevent references from stopping updates. The use of output admissible sets for a class of variable constraints is exploited to form invariant sets. Simulation results based on a turbofan engine model show that references governors with limit governors can effectively enforce the multiple constraints and provide enhanced engine thrust when steady violation occurs.
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Hu, Lichen, Feiyu Long, Borui Xie, and Xuanzhou Zhuang. "Four variants of turbofan, turbojet, turboprop and ramjet engines and their future prospects." Applied and Computational Engineering 11, no. 1 (September 25, 2023): 137–42. http://dx.doi.org/10.54254/2755-2721/11/20230222.
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A jet engine is a sophisticated machine that has revolutionized the aviation industry. It is a type of internal combustion engine that uses air as its oxidizer and fuel to produce thrust. The third law of motion, which states that there is an equivalent and opposite response to every action, governs how the engine functions. Compressed air is combined with fuel, ignited in the combustion chamber, and then expelled out of the jet engine at a high rate of speed to create propulsion. The development of jet engines has been a long and arduous process, with many different designs and configurations over the years. Early jet engines were inefficient, noisy, and prone to failure. However, technological advances have created more efficient and reliable engines in various applications, from commercial aviation to military aircraft and even spacecraft. The efficiency and reliability of jet engines have transformed air travel, enabling faster and more efficient travel over long distances. This has increased global connectivity, economic growth, and cultural exchange. However, jet engines also have environmental impacts, such as noise pollution and greenhouse gas emissions, which have led to the development of more environmentally friendly engines.
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Guérin, S., R. Schnell, and R. G. Becker. "Performance prediction and progress towards multi-disciplinary design of contra-rotating open rotors." Aeronautical Journal 118, no. 1208 (October 2014): 1159–79. http://dx.doi.org/10.1017/s0001924000009830.
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Abstract At DLR’s Institute of Propulsion Technology, the prediction tools and multi-disciplinary optimisation strategies developed for turbofan engines have been extended to contra-rotating open rotors (CROR). Thereby the objective has been to appraise and improve the performance of CROR engines and thus to reduce their environmental impact. The present paper reviews the intermediate progress achieved in this scope. The prediction is based on analytical and CFD methods and covers the fields of engine performance analysis, aerodynamics and acoustics. The aerodynamic and acoustic results could be partly validated through the comparison to experimental data obtained from wind-tunnel tests. In a multi-disciplinary approach the aforementioned aspects are optimised together. First results of an aero-acoustic optimisation are presented. Furthermore this paper undertakes some comparison between high-bypass ratio turbofan engines and open-rotor concepts.
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Langston, Lee S. "For Jet Engine Wing Mounting." Mechanical Engineering 140, no. 09 (September 1, 2018): S52—S53. http://dx.doi.org/10.1115/1.2018-sep4.
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The mounting of a jet engine under the wing of an airliner can be a daunting task for turbofan engineers. Thrust forces generated by gas path momentum flow changes in a jet engine are transmitted by pressure (and friction) forces on stators and struts attached to the engine case. Case engine mounts then transmit the thrust forces (as high as 100,000 pounds thrust on the largest engines) to the wing pylons to pull the plane forward. The mounts must also support the engine weight (as high as 20,000 pounds) and carry nacelle flight loads. Engine bypass ratios are increasing (12:1 on the new geared fan engines), with fan sizes ever growing (178 inch diameter fan on the new GE9X). Mounting these new engines under a wing can present new challenges. During the early days of its introduction in the late 1960’s, Boeing’s iconic 747 jumbo jet had engine mount problems. These are examined, together with their solution.
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Hrncirzdenek and Chris Hickenbottom. "A Practical Example of Applying Machine Learning to a Real Turbofan Engine Issue: NEOP." PHM Society European Conference 8, no. 1 (June 27, 2024): 7. http://dx.doi.org/10.36001/phme.2024.v8i1.4103.
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There are high expectations for the use of Machine Learning algorithms in Engine Health Management, but the practical application for use with turbofan engines is often hindered by small sample sizes and noisy data. This paper discusses a case in which Machine Learning techniques were combined with domain expertise to develop a classifier called Non-seal Erratic Oil Pressure (NEOP). This classifier is used as an engineering tool to support manual review of engines flagged with Honeywell’s OPX (Oil Pressure Transducer) algorithm. The purpose of the classifier is to assist a human in analyzing engine trend data from the HTF7000 turbofan engine, when the OPX algorithm identifies an engine with erratic oil pressure. The NEOP history provides an additional data source when deciding if aft sump maintenance is needed to replace a worn carbon seal, or if the erratic signal is associated with some other cause. The OPX algorithm has enabled the prevention and avoidance of costly unscheduled engine failures resulting in millions of dollars in documented savings, and the NEOP algorithm helps to ensure that the conclusions from the OPX process continue to result in the appropriate engines being identified for maintenance inspection and corrective action.
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Tkachenko, Andrey, Evgeny Filinovaroslav Ostapyuk, Viktor Rybakov, and Daria Kolmakova. "Thermodynamic designing of the small-scale gas turbine engine family with common core." MATEC Web of Conferences 220 (2018): 03007. http://dx.doi.org/10.1051/matecconf/201822003007.
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The paper describes the method of selecting the working process parameters of a family of small-scale gas turbine engines (GTE) with common core. As an example, the thermodynamic design of a family of small-scale gas turbine engines (SGTE) with common core was carried out. The engine family includes a small-scale turbojet engine (STJE) and a gas turbine plant (GTP), which electric generator is driven by power turbine. The selection of rational values for the working process parameters of STJE and GTP was carried out in CAE system ASTRA on the basis of nonlinear optimization of these parameters, taking into account functional and parametric constraints. The quantitative results of deterioration in the performance of the engines of the family with common core are obtained in comparison with the engines with the optimum core for each type. However, the advanced creation of a common core can reduce the cost and timing of the engine creation, ensure its higher reliability (due to the development of the base common core) and reduce the cost of its production. The method of selecting the parameters of the working process of the GTE family with common core presents the solution to more complex problems, such as the possibility of developing a family consisting of five engines: a turbojet engine, turbofan engine, turbofan engine with a complex cycle, GTE with power turbine (GTE-PT), GTE-PT with recovery.
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SZRAMA, Sławomir. "F-16 turbofan engine monitoring system." Combustion Engines 177, no. 2 (May 1, 2019): 23–35. http://dx.doi.org/10.19206/ce-2019-205.
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The multirole F-16 is the most advanced aircraft in the Polish Air Forces. It has been equipped with the very modern, sophisticated and advanced turbofan engine F100-PW-229. Due to the fact, that there is only one engine, its reliability, durability, efficiency and performance are the crucial factors for the safety reasons. In the article author researched maintenance system of the F100 turbofan engines, to describe Engine Monitoring System features. Engine Monitoring System (EMS) is the key element in the engine prognostic and health monitoring. The EMS provides engine fault indicators to the pilots and technicians and with the engine performance trending affects the F-16 flight safety risk and enhanced engine maintenance management concept. The main goal of this article was to provide information on the F-16 Engine Monitoring System and its impact on the aircraft airworthiness and F-16 fleet readiness resulting from the engine reliability. It is also an introduction to the F-16 Engine Health Management concept.
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Ahmed, Fawwad, Ahmad Aizaz, and Zahid Mahmood. "Mechanical Design to Adapt Changes to Existing Universal Test Bed Facility of Turbojet Engine for the Turbofan Engine." Advanced Materials Research 983 (June 2014): 374–78. http://dx.doi.org/10.4028/www.scientific.net/amr.983.374.
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The existing Universal Test Bed (UTB) is a facility to ground test Turbojet Engines before installation on the aircraft. This work provides a feasibility study to adapt changes to this UTB for the Turbofan Engine. Necessary design modification of existing UTB is performed by applying propulsive and structural analysis for the adaptation of Turbofan engine. Physical measurements of the UTB and the mounts of Turbofan Engine reveal their mutual compatibility. Based on these measurements, six different CAD models are generated in Solid Works® and analyzed in ANSYS® Workbench. After grid independence check, validation of the model with applied loads and the boundary conditions was done through comparison of analytical calculations with those of a simplified CAD model. Based on minimum stress vis-à-vis maximum Factor of Safety (FOS), the best design is finally selected through this research.
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Gerasimenko, Volodymyr, Vadym Datsenko, and Mikhail Shevchenko. "CREATION OF AFTERBURNING TURBOFAN ENGINE – HISTORY AND PRESENT." Aerospace technic and technology, no. 5 (August 29, 2020): 26–40. http://dx.doi.org/10.32620/aktt.2020.5.04.
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The main problems of the creation of afterburning turbofan engines, among which the irremovable surge of the compressor, is disclosed by historical analysis. According to the published models, such surge is a hydrodynamic instability in the form of rotating stall mutual transitions to surge with the primary cause of instability in the form of stall or vibration combustion in the afterburner. The Pratt & Whitney F100 serial engine, which based on TF30 is one of the first in which the irremovable surge was detected. As a result, several planes F-15 crashed, so far as the compressor could not be restored to a stable state without stopping and restarting the engine. Dissection of the problem with this phenomenon led to the conclusion that this irremovable surge problem was generated by the engine design. To eliminate it, the company had to refine several systems, such as an electronic engine control system, fuel supply of the afterburner along with the nozzle locations, firing belt, combustion stabilization, an extension of flow separation along the contours, etc. According to the analysis of publications, particular difficulties arose with the recoverable unsurge operation of such engines. It is noteworthy that today, the F-135-PW100 engines have been installed on the F-35 aircraft, the predecessors of which are the F-100 engines with the same problems. The results of experimental studies of a fan are presented in the article to deepen in the stall flow mechanism and the occurrence of rotating stall of the fan blades. The perturbations from vibrational combustion in the afterburner combustion chamber to the fan stall boundary in the afterburning turbofan engine system at bench conditions were simulated by independent throttling of the duct over a wide range of the bypass ratio. Numerous monographs and publications according to vibrational combustion, in particular in afterburner combustion chambers TRDF AL-21F and TRDDF AL-31F, of A. M. Lulka, confirm the possibility of the propagation of perturbations against the flow in the bypass duct and the impossibility of their propagation through the turbines. The propagation of surge perturbations in the afterburning turbofan engine to the compressor of the internal duct behind the fan occurs through the interaction of the duct. The more reliable way to prevent emergencies is to provide stability margin area of compressors. Estimation of the pre-stall state of the flow traditionally is carried out by the diffusivity factor of Lieblein FD, which is applicable in 2D calculations. The integral variational principle of nonequilibrium thermodynamics of the “maximum flow of mechanical energy” of V. N. Yershov was applied.
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Ensarioğlu, Kıymet, Tülin İnkaya, and Erdal Emel. "Remaining Useful Life Estimation of Turbofan Engines with Deep Learning Using Change-Point Detection Based Labeling and Feature Engineering." Applied Sciences 13, no. 21 (October 30, 2023): 11893. http://dx.doi.org/10.3390/app132111893.
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Accurate remaining useful life (RUL) prediction is one of the most challenging problems in the prognostics of turbofan engines. Recently, RUL prediction methods for turbofan engines mainly involve data-driven models. Preprocessing the sensor data is essential for the performance of the prognostic models. Most studies on turbofan engines use piecewise linear (PwL) labeling, which starts with a constant initial RUL value in normal/healthy operating time. In this study, we designed a prognostic procedure that includes difference-based feature construction, change-point-detection-based PwL labeling, and a 1D-CNN-LSTM (one-dimensional–convolutional neural network–long short-term memory) hybrid neural network model for RUL prediction. The procedure was evaluated on the subset FD001 of the C-MAPSS dataset. The proposed procedure was compared with machine learning and deep learning models with and without the new difference feature. Also, the results were compared with the studies that used similar labeling approaches. Our analysis of the numerical results underscores the clear superiority of the proposed 1D-CNN-LSTM model with the difference feature in RUL prediction, with a score of 437.2 and an RMSE value of 16.1. This result illustrates the superior predictive capability of the 1D-CNN-LSTM model, which outperformed traditional machine learning methods and one of the earliest deep learning methods. These findings emphasize the superior predictive capability of the 1D-CNN-LSTM model and underline the potential of the feature engineering process for more accurate and robust RUL prediction in the context of turbofan engine prognostics.
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Vankan, Wilhelmus J., Robert Maas, and Vincent Peyron. "Optimisation methodology for integrated equipment installation in new engine architecture nacelles." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 234, no. 10 (December 21, 2019): 1706–20. http://dx.doi.org/10.1177/0954410019895883.
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The development of new higher efficiency turbofan aero engines requires several design enhancements that typically result in shorter and slimmer nacelles. Consequently these engines provide less space for the engine systems installation and for maintenance accessibility. In the Novel Integration of Powerplant System Equipment project, optimisation methodologies are being investigated and developed for the integrated installation of equipment into the restricted volume of new architecture engines’ nacelles. The underlying optimisation methodology is built on a graph based approach involving efficient routing algorithms. Besides the methodology, also the software implementation and its application to engine equipment installation design cases are presented in this paper.
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Langston, Lee S. "Fitting a Pitch." Mechanical Engineering 131, no. 12 (December 1, 2009): 38–42. http://dx.doi.org/10.1115/1.2009-dec-4.
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This article discusses gas turbine efficiency, which is an essential but often unappreciated aspect of turbomachine design pitch. To an engineer, the pitch of a turbo machinery blade is the angle at a representative blade cross-section between the blade chord line and the plane of the blade’s rotation. An axial flow gas turbine consists of many rows of rotating blades, interspersed with rows of stationary airfoils, called vanes or stators. The gas turbine compressor (whose first row of rotating blades in a jet engine may be a fan) draws in air, which after passing through a combustor to add energy to the air flow, powers the turbine which drives the compressor. Most modern commercial jet engines are turbofan, with a front mounted fan, whose size is indicated by the bypass ratio. During the 1990s, jet engine companies developed and tested variable pitch turbofans, with cycle studies showing between 6 and 14% fuel savings. If fuel savings could spread through the airline industry, changing the pitch could lead to air carriers singing a happier tune.
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ISHIZAWA, Kazuhiko. "Development of advanced V2500 turbofan engines." Journal of the Japan Society for Aeronautical and Space Sciences 41, no. 479 (1993): 665–72. http://dx.doi.org/10.2322/jjsass1969.41.665.
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Wang, Hairui, Dongwen Li, Dongjun Li, Cuiqin Liu, Xiuqi Yang, and Guifu Zhu. "Remaining Useful Life Prediction of Aircraft Turbofan Engine Based on Random Forest Feature Selection and Multi-Layer Perceptron." Applied Sciences 13, no. 12 (June 15, 2023): 7186. http://dx.doi.org/10.3390/app13127186.
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The accurate prediction of the remaining useful life (RUL) of aircraft engines is crucial for improving engine safety and reducing maintenance costs. To tackle the complex issues of nonlinearity, high dimensionality, and difficult-to-model degradation processes in aircraft engine monitoring parameters, a new method for predicting the RUL of aircraft engines based on the random forest algorithm and a Bayes-optimized multilayer perceptron (MLP) was proposed here. First, the random forest algorithm was used to evaluate the importance of historical monitoring parameters of the engine, selecting the key features that significantly impact the engine’s lifetime operation cycle. Then, the single exponent smoothing (SES) algorithm was introduced for smoothing the extracted features to reduce the interference of original noise. Next, an MLP-based RUL prediction model was established using a neural network. The Bayes’ online parameter updating formula was used to solve the objective function and return the optimal parameters of the MLP training model and the minimum value of the evaluation index RMSE. Finally, the probability density function of the predicted RUL value of the aircraft engine was calculated to obtain the RUL prediction results.The effectiveness of the proposed method was verified and analyzed using the C-MAPSS dataset for turbofan engines. Experimental results show that, compared with several other methods, the RMSE of the proposed method in the FD001 test set decreases by 6.1%, demonstrating that the method can effectively improve the accuracy of RUL prediction for aircraft engines.
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Sun, Penghui, Xi Wang, Shubo Yang, Bei Yang, Huairong Chen, and Bin Wang. "Bumpless Transfer of Uncertain Switched System and Its Application to Turbofan Engines." Energies 14, no. 16 (August 23, 2021): 5204. http://dx.doi.org/10.3390/en14165204.
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Nonlinear control problems in turbofan engines are challenging. No single nonlinear controller can achieve desired control effects in a full flight envelope, but in the case of multiple controllers, there exist problems in the bumpless transfer between different controllers. To this end, this paper presents a bumpless transfer mechanism for an uncertain switched system based on integral sliding mode control (ISMC), and the mechanism can be used for the speed control of turbofan engines. The uncertain switched system is used to describe the turbofan engine dynamics. Then, the ISMC controller is derived for subsystems of the uncertain switched system. A resetting scheme is introduced for the ISMC controller to ensure the continuity of control inputs during the controller transition, as well as the bumpless transfer. In view of the transient behavior caused by controller switching, the global stability of the switched system is analyzed using the multiple Lyapunov function approach and average dwell time condition. Simulation results validate that the designed resetting scheme can ensure the continuity of control input signals and avoid the instability caused by high-frequency controller switching, and increase the control effectiveness of the proposed ISMC method within the full flight envelope.
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Aleid, L., and P. Pilidis. "Variable cycle jet engines for a Mach 2·7 supersonic civil transport." Aeronautical Journal 102, no. 1011 (January 1998): 31–36. http://dx.doi.org/10.1017/s0001924000065714.
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AbstractThe aim of the work outlined in this paper is to compare three different variable cycle jet engine concepts for future SSTs. These engines are: the turbofan-turbojet, the mid-tandem fan engine and the double bypass engine. The comparison is carried out on the basis of unin-stalled and installed performance, handling and sizing issues.This preliminary analysis compares SFC, size, variable geometry and cycle changes for each engine. The installed performance was estimated by calculating the air friction, the pre-entry and the afterbody drags, together with the wave drag due to the shock waves. A sizing calculation was carried out for the whole nacelle. The uninstalled and installed fuel bill, for two standard missions, is also estimated.These preliminary results indicate that the turbofan-turbojet and the mid-tandem fan engines are quite similar in terms of general suitability. The mid-tandem fan appears to be an attractive proposition from the point of view of sizing, however, this comes with a small penalty in fuel consumption. The present double bypass engine was found to be the least attractive for the application, although the differences are small.
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Ommi, Fathollah, and Mohammadreza Azimi. "MAIN FAN NOISE MITIGATION TECHNOLOGIES IN TURBOFAN ENGINES." Aviation 18, no. 3 (October 2, 2014): 141–46. http://dx.doi.org/10.3846/16487788.2014.969881.
Full textAbstract:
Aircraft noise and emissions have been of concern since the beginning of commercial aviation. The continuing growth in air traffic and increasing public awareness have made environmental considerations one of the most critical aspects of commercial aviation today. To deal with this problem, aircraft manufacturers and public establishments are engaged in research on technical and theoretical approaches for noise reduction concepts that should be applied to new aircraft. While jet noise was the dominating contributor in the early jet engine designs, the noise emitted by the fan has become important with the reduction in jet speed and its control requiring an immense research effort. This paper concerns the main fan noise mitigation technologies in turbofan engines.
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Dunn, M. G., C. Padova, J. E. Moller, and R. M. Adams. "Performance Deterioration of a Turbofan and a Turbojet Engine Upon Exposure to a Dust Environment." Journal of Engineering for Gas Turbines and Power 109, no. 3 (July 1, 1987): 336–43. http://dx.doi.org/10.1115/1.3240045.
Full textAbstract:
Results are reported for a measurement program designed to investigate the performance deterioration of a TF33 turbofan and a J57 turbojet engine upon exposure to a dust-laden environment. Engine parameters were measured in order to facilitate the recognition of incipient engine difficulties. In addition, a successful effort was made to operate the engines satisfactorily when they were severely damaged. Two TF33 engines have been operated in the same dust mixture but under different operating conditions and a J57 engine was operated at the same conditions as one of the TF33 engines. The JS7 is the core engine of the TF33 with some differences that will be described in the paper. A description of the experimental technique, the operating experiences, photographs of the components taken from the J57 engine in a post-test teardown, and a discussion of the results are presented.