Showing papers on "Turbofan published in 2021"

Effects of Bypass Ratio Change Trend on Performance in a Military Aircraft Turbofan Engine With Comparative Assessment

Abstract: In this study, it is aimed to observe the bypass effects on energetic and exergetic performance in a JT3D-3B Military Aircraft Turbofan Engine and its components. For this aim, the comprehensive energy and exergy analyses are performed separately at the various bypass ratios: BPR: 1.30 (Case A), BPR: 1.34 (Case B), BPR: 1.38 (Case C), BPR: 1.40 (Case D), BPR: 1.42 (Case E), BPR: 1.45 (Case F), and BPR: 1.36 (original design). As per the performance results, while the energetic efficiency of the engine is found to be 27.93% for Case F, 27.85% for Case E, 27.72% for Case D, 27.60% for Case C, 27.17% for Case B, 26.97% for Case A, the exergetic efficiency of the engine is found to be 26.23% for Case F, 26.23% for Case E, 26.11% for Case D, 26.00% for Case C, 25.59% for Case B, and 25.39% for Case A, Furthermore, with the increase of bypass ratio step by step from 1.30 to 1.45, while the energetic efficiency, the exergetic efficiency, the relative exergy consumption value tends to increase, the fuel exergy waste ratio value, the productivity lack ratio, and exergetic improvement potential value of the overall engine tends to decrease. This study can be helpful for turbofan engine users, owners, and designers.

Thermodynamic Performance and Creep Life Assessment Comparing Hydrogen- and Jet-Fueled Turbofan Aero Engine

Abstract: There is renewed interest in hydrogen as an alternative fuel for aero engines, due to their perceived environmental and performance benefits compared to jet fuel. This paper presents a cycle, thermal performance, energy and creep life assessment of hydrogen compared with jet fuel, using a turbofan aero engine. The turbofan cycle performance was simulated using a code developed by the authors that allows hydrogen and jet fuel to be selected as fuel input. The exergy assessment uses both conservations of energy and mass and the second law of thermodynamics to understand the impact of the fuels on the exergy destruction, exergy efficiency, waste factor ratio, environmental effect factor and sustainability index for a turbofan aero engine. Finally, the study looks at a top-level creep life assessment on the high-pressure turbine hot section influenced by the fuel heating values. This study shows performance (64% reduced fuel flow rate, better SFC) and more extended blade life (15% increase) benefits using liquefied hydrogen fuel, which corresponds with other literary work on the benefits of LH2 over jet fuel. This paper also highlights some drawbacks of hydrogen fuel based on previous research work, and gives recommendations for future work, aimed at maturing the hydrogen fuel concept in aviation.

Propulsion system integration for a first-generation hydrogen civil airliner?

Abstract: An unusual philosophical approach is proposed here to decarbonise larger civil aircraft that fly long ranges and consume a large fraction of civil aviation fuel. These inject an important amount of carbon emissions into the atmosphere, and holistic decarbonising solutions must consider this sector. A philosophical–analytical investigation is reported here on the feasibility of an airliner family to fly over long ranges and assist in the elimination of carbon dioxide emissions from civil aviation. Backed by state-of-the-art correlations and engine performance integration analytical tools, a family of large airliners is proposed based on the development and integration of the body of a very large two-deck four-engine airliner with the engines, wings and flight control surfaces of a very long-range twin widebody jet. The proposal is for a derivative design and not a retrofit. This derivative design may enable a swifter entry to service. The main contribution of this study is a philosophical one: a carefully evaluated aircraft family that appears to have very good potential for first-generation hydrogen-fuelled airliners using gas turbine engines for propulsion. This family offers three variants: a 380-passenger aircraft with a range of 3,300nm, a 330-passenger aircraft with a range of 4,800nm and a 230-passenger aircraft with a range of 5,500nm. The latter range is crucially important because it permits travel from anywhere in the globe to anywhere else with only one stop. The jet engine of choice is a 450kN high-bypass turbofan.

Design of a single degree of freedom acoustic liner for a fan noise test rig

Abstract: Acoustic liners are an essential part of noise reduction technologies commonly applied in aircraft turbofan engines. Fan noise suppression can be achieved by selecting an appropriate liner design w...

CNN-Based Intelligent Fault-Tolerant Control Design for Turbofan Engines With Actuator Faults

Abstract: In this paper, the problem of fault-tolerant control is investigated for turbofan engines with actuator faults. The controller involvement has repressed the effects of actuator faults on the controlled outputs of turbofan engines, making fault-tolerant control difficult. To solve this problem, the internal gas-path data of turbofan engines is introduced to provide conducive fault information. Besides, the useful property of the convolution neural network (CNN) is explored and utilized in fault-tolerant control. Based on the analysis of actuator faults, by using the Lyapunov stability and $L_{2}$ -gain like theorems, a novel CNN-based intelligent fault-tolerant control system for turbofan engines is proposed, including a CNN-based fault diagnosis module and a nonlinear fault-tolerant control with corresponding reconfiguration unit. The CNN-based intelligent fault-tolerant control system has the advantages of reducing the accuracy requirements of the mathematical description of turbofan engines. Furthermore, the proposed system can diagnose actuator faults and reduce the adverse effects of actuator faults on turbofan engines. Finally, simulation results are presented to demonstrate the efficiency of the designed method.

Fully Coupled Body Force–Engine Performance Methodology for Boundary Layer Ingestion

Abstract: Because of their potential reductions of fuel consumption, disruptive propulsion concepts such as boundary layer ingestion have lately earned the attention of the aerospace community. Because of th...

Low-Speed Turbofan Aerodynamic and Acoustic Prediction with an Isothermal Lattice Boltzmann Method

Abstract: The objective of this paper is to assess the capability of the isothermal lattice Boltzmann method (LBM) to correctly capture aerodynamic and acoustic features from a low-speed turbofan. The evalua...

Aerodynamic Analysis and Design of a Rim-Driven Fan for Fast Flight

Abstract: This paper discusses the aerodynamic analysis and design of a novel, hubless, contra-rotating, rim-driven fan (RDF) device. Rim-driven thruster technology has been used for marine propulsion for de...

Event-triggered control for switched linear systems: A control and switching joint triggering strategy.

Abstract: The present work addresses the stability issue of switched linear systems (SLSs) subject to event-triggered control. We presume that the feedback controller acquires the switching signals and systems state information only at event-triggered sampling instants. An event triggering strategy is presented for both control and switching. Meanwhile, sufficient condition is obtained to stabilize the event-triggered switched linear systems. In addition, we prove that the Zeno behavior can be excluded through the proposed event triggering strategy. Finally, the speed regulation of a turbofan engine model shows that the derived technique is practicable.

Modeling and dynamic characteristic analysis of dual rotor-casing coupling system with rubbing fault:

Abstract: With the rapid development of aero-engine manufacturing technology, the dual-rotor system has been employed in part of turbofan engine in order to improve the working performance of aircraft more e...

Enhanced cruise range prediction for narrow-body turbofan commercial aircraft based on QAR data

Abstract: Aircraft performance parameters play a critical role in maintaining economic and environmental sustainability in aviation. Furthermore, the ability to calculate aircraft performance parameters accurately for the cruise range contributes to aviation in areas such as the preliminary design of aircraft and air traffic management. This study is focused on cruise range performance, as this is critical to both the evaluation and understanding of the economic and environmental impacts of commercial aircraft. Quick Access Recorders (QAR) data were used for more accurate analysis of the cruise range. The QAR data used in this study included 6,574 short-distance domestic flights by narrow-body turbofan commercial aircraft between 31 different city pairs. To obtain a more accurate cruise range equation, parameters affecting the cruise range performance were determined and studied. First, the drag polar model was improved to take the cambered profile, compressibility effects and cruise airspeeds of commercial aircraft into consideration using the real flight data. Second, Thrust-Specific Fuel Consumption (TSFC) models were compared and the most suitable one for the cruise phase was selected. After these steps, cruise range values were calculated using the Breguet range equation with these improved parameters. When the results of this enhanced range model were compared with the real flight data, the mean absolute percentage error (MAPE) was found to be 2.5% for all the Aircraft and Engine Type Groups (AETGs) considered in the data. This figure corresponds to a 7.9% smaller error than provided by previous range models based on simple parabolic drag polar and TSFC models. According to these results, the application of a simple parabolic drag polar and TSFC is not appropriate for cruise range calculations.

Predictive modelling of turbofan engine components condition using machine and deep learning methods

Abstract: A modern aircraft’s turbofan engine is a complex mechanical system with numerous components that need to be properly maintained to continue its safe and profitable operation. As the components deteriorate they need to be replaced or repaired which drive the engine off wing for often time consuming overhaul [8] and creates a cost burden requiring proper engine fleet management to continue the aircraft operation [18]. Aircraft engine components condition is assessed on recurring inspections and compared to the limits provided by the engine manufacturer which constitute the Instructions for Continued Airworthiness approved and controlled by the regulatory agency in a form of an engine manual [16]. The engine manual limits proposed by the engine manufacturer are based upon understanding of the physics behind the particular wear out scheme and the condition progression until the part cannot be operated any longer and has to be replaced. With the complexities of loads that parts are exposed to a variety of competing failure modes occuring at different stages of part’s age and progresing at different rates comes with significant impact of enThe article proposes an approach based on deep and machine learning models to predict a component failure as an enhancement of condition based maintenance scheme of a turbofan engine and reviews currently used prognostics approaches in the aviation industry. Component degradation scale representing its life consumption is proposed and such collected condition data are combined with engines sensors and environmental data. With use of data manipulation techniques, a framework for models training is created and models' hyperparameters obtained through Bayesian optimization. Models predict the continuous variable representing condition based on the input. Best performed model is identified by detemining its score on the holdout set. Deep learning models achieved 0.71 MSE score (ensemble meta-model of neural networks) and outperformed significantly machine learning models with their best score at 1.75. The deep learning models shown their feasibility to predict the component condition within less than 1 unit of the error in the rank scale. Highlights Abstract

An estimation method for the fuel burn and other performance characteristics of civil transport aircraft during cruise: part 2, determining the aircraft’s characteristic parameters

Abstract: A simple yet physically comprehensive and accurate method for the estimation of the cruise fuel burn rate of turbofan powered transport aircraft operating in a general atmosphere was developed in part 1. The method is built on previously published work showing that suitable normalisation reduces the governing relations to a set of near-universal curves. However, to apply the method to a specific aircraft, values must be assigned to six independent parameters and the more accurate these values are the more accurate the estimates will be. Unfortunately, some of these parameters rarely appear in the public domain. Consequently, a scheme for their estimation is developed herein using basic aerodynamic theory and data correlations. In addition, the basic method is extended to provide estimates for cruise lift-to-drag ratio, engine thrust and engine overall efficiency. This step requires the introduction of two more independent parameters, increasing the total number from six to eight. An error estimate and sensitivity analysis indicates that, in the aircraft’s normal operating range and using the present results, estimates of fuel burn rate are expected to be in error by no more than 5% in the majority of cases. Initial estimates of the characteristic parameters have been generated for 53 aircraft types and engine combinations and a table is provided.

Multi-dimensional energetic performance modeling of an aircraft engine with the aid of enhanced least–squares estimation based genetic algorithm method

Abstract: Aircraft must have reliable and sustainable sources of power systems and must use energy efficiently. Aircraft engine advances have dramatically improved aircraft fuel efficiency. Variable cycle engine (VCE) has been promising in both civil and military areas in the last decades. An important challenge for energy saving regarding the engine is to find optimum flight conditions. For this aim, this study investigated energetic and exergetic off-design performance modeling of the variable cycle turbofan engine with respect to flight conditions and potentially energy benefits for a new-generation combat aircraft. Current analysis mainly focused on how to simplify off-design performance model of the VCE in terms of thrust, specific fuel consumption (SFC), overall and exergy efficiencies with the aid of enhanced least-squares estimation-based genetic algorithm (LSEGA) in flight phases. According to analyses, the results show that the proposed method is capable of modeling all the thermodynamic off-design parameters with root mean square error values of as low as 0.000162 for exergy efficiency, 0.000311 for overall efficiency, 1.007 for thrust and 0.0763 for SFC. It is observed from the study that the proposed LSEGA algorithm has successfully converged into optimal solutions for all indexes and flight regimes and all the off-design performance models of the VCE energetic indexes are obtained with high accuracy.

Turbofan engine assembly with fan case liner cartridge

Abstract: A turbofan engine has a fan having a circumferential array of fan blades. A fan case encircles the fan. There is at least one compressor section, a combustor, and at least one turbine section. The fan case comprises a containment case (100) and a cartridge liner carried therein. A ballistic liner (190) encircles at least a portion of the cartridge liner and is attached thereto.

An acoustic liner design methodology based on a statistical source model

Abstract: The attenuation of fan tones remains an important aspect of fan noise reduction for high bypass ratio turbofan engines. However, as fan design considerations have evolved, the simultaneous reductio...

Architecture of Distributed Control System for Gearbox-Free More Electric Turbofan Engine

Abstract: This article presents the development of the electric turbofan engine in distributed architecture with a design thrust in the range of 3 to 7.5 and from 7.5 to 30 kN for small and medium-sized unmanned aerial vehicles. The engine subsystems are considered as separate smart modules with a built-in control system, exchanging data via a digital channel with the central engine control and diagnostics unit. The key smart engine units are combined in the following subsystems: starter and turbine generators, oil pumps, actuator of guide vanes, fuel pumps, fuel metering unit, control and diagnostic unit. All pumps and guide vane actuator are electrically driven. Control and monitoring signals are transmitted via a digital bus. Functional and reliability analysis and the technical configuration design of each subsystem are presented. Based on analysis of the architecture of distributed control systems for a gearbox-free electric engine, different configurations of described subsystems are proposed.