Performance Of Turbofan Engine Research Articles

A fault-tolerant acceleration control strategy for turbofan engine based on multi-layer perceptron with exponential Gumbel loss

The acceleration performance of turbofan engine is mainly limited by the surge boundary of high-pressure compressor (HPC). A certain amount of surge margin (SM) is reserved between the boundary and the acceleration schedule (AS) of acceleration control to avoid the risk caused by intake distortion, etc. However, the performance improvement by low SM design is the requirement for advanced engines. Hence it must execute a fault-tolerant strategy for the impact of sensor error, fuel metering error, etc. This paper proposes a method by adopting four ASs for weighted average to replace the single AS. The weights are altered by the multi-layer perceptron with reference to the real-time fuel results from four ASs, intake condition and rotor speed. For safety and accuracy, an exponential Gumbel loss function is introduced into the model training. The simulation results demonstrate that the method can significantly tolerate the impact of a single fault and the normal deviations of other factors without causing SM of HPC to be less than 3.6%. These also indicate that the acceleration time on the ground does not exceed acceptable 5 s, with a median that is 0.34 s less than the minimum method of two ASs within the flight envelope.

Investigation of overall performance of turbofan engine with pulse detonation combustor in bypass duct

The performance model was established to study the performance of mixed exhaust turbofan engine with pulse detonation combustor (PDC) in the bypass duct. The effects of the total pressure loss of isolator and bypass circulation parameters on the characteristic of PDC and performance of engine were analyzed. Then, the sensitivity analysis of performance parameters was carried out on the influence of the components parameters. The performance of mixed exhaust turbofan engine with PDC in the bypass duct was compared with that of the conventional afterburner turbofan engine at the same design circulation parameters. The results show that to increase the total pressure loss of isolator is beneficial to the improvement of performance because of the improvement of pressure ratio; when fan pressure ratio is constant, with the increasing of bypass ratio, the specific fuel consumption and specific thrust increase; with the increasing of fan pressure ratio, when bypass ratio is 0.2 to 0.4, specific thrust increases first and then decreases. When bypass ratio is 0.4 to 0.5, specific thrust increases first and then remains constant. When bypass ratio is 0.5 to 0.9, specific thrust increases, but the rate of increase reduces. At different bypass ratio, specific fuel consumption decreases with increasing of fan pressure ratio; the performance of engine is more sensitive to the component parameters that directly affect the flow state parameters of the bypass duct; because of supercharging performance of PDC, PDC in the bypass duct only uses part of air flow to organize combustion that can make specific thrust of turbofan engine with PDC in the bypass duct and conventional afterburner turbofan engine are equivalent. Meanwhile, specific fuel consumption can be reduced by 27.7% at design point and 12.8%-26.8% at off-design points.

Development of a Predictive Tool for the Parametric Analysis of a Turbofan Engine

Parametric cycle analysis, an on-design engine study, specifies the required design characteristics that optimize engine performance. This study aimed to conduct a parametric analysis of a low-bypass turbofan engine with an afterburner, F100-PW229, and develop a technique for estimating its performance based on data using machine learning and deep learning. Commercially available gas turbine simulation software, GasTurb 14, was used to create a dataset of engine performance response variables and input design parameters. The effects of the Mach number, fan pressure ratio, altitude, turbine entry temperature, and bypass ratio on the specific thrust, propulsive efficiency, specific fuel consumption, and total fuel flow were investigated. Regression learning models and deep neural networks were then programmed on this dataset to predict responses for new input data. In MATLAB, a total of 24 regression models were trained with cross-validation, and the model with the least root mean square error was selected as the final model. The machine learning regression models produced reliable output parameter predictions, with the least root mean square error of 9.076 × 10−5. Among the numerous regression models tested, Gaussian process regression, the quadratic support vector machine, and the wide neural network emerged to be the most successful in predicting turbofan engine performance metrics. A multilayer perceptron model was coded in Python with two hidden layers that accurately predicted the performance parameters. The mean square error value on test data was found to be as low as 0.0046. In comparison to intensive computational simulations, machine learning and deep learning models offer an efficient method for conducting parametric analysis of turbofan engines.

Assessment of performance degradation of a mixed flow low bypass turbofan engine through GasTurb simulation

Abstract Aero engine performance analysis is very important for engines under development as well as for engines in service for condition monitoring. Predictions of aero engine performance and ability of building the simulation model is an invaluable asset for designers, manufacturer and end-use operator. This paper presents the methodology in establishing the baseline performance of a twin spool mixed flow low bypass turbofan engine through extensive testing at engine test bench. The baseline data is used to validate a GasTurb model which is subsequently used for assessment of off-design performance and component degradation responsible for performance deterioration at various service hours. The estimated exhaust gas temperatures by the model for degraded engines are in good agreement with the measured data. The model further assesses the drop in HP compressor efficiency and shift in operating line which will be very useful for taking judicious decision for withdrawal of engines and is expected to reduce or delay withdrawals and increase the availability of engines at operating base.

마이크로 터보제트 엔진의 터보팬 파생개발 연구

A study to modify and develop a turbofan engine using a micro turboprop engine has been conducted. The turbofan engine has been designed by adding a fan blade module as well as other required accessories to the existing turboprop engine. CFD and FEM methods were used for numerical analyses of the additional fan module to assess its aerodynamic performance and structural stability. Components of the fan module were fabricated with consideration for manufacture and assembly, and a test rig was also designed and built to measure the turbofan engine performance. The performances of the turbofan engine were measured and compared to an existing micro-turbojet engine. The performance tests were conducted in two phases: In the first phase, the robustness of the designed turbofan and test rig were investigated and in the second phase, the maximum power test has been conducted to measure performance variables such as engine thrust, engine exhaust temperature(EGT) and fuel flow rate according to the engine RPM. The test results indicated that the turbofan engine SFC was reduced by 40∼50% of the existing turbojet engine, demonstrating the successful implementation of turbofan characteristics.

High bypass turbofan engine and anti-icing system performance: Mass flow rate of anti-icing bleed air system effect

Most aircraft are flying at high altitude which can cause icing accumulation, changes the wing profile and the aerodynamic characteristics of wing. The anti-icing bleed air system (AI-BAS) is considered an important system used to prevent the icing accumulation using hot air from engine (bleed); but it may lead to reduced engine performance. This work aims to study the effect of bleed variation on engine performance and (AI-BAS). The bleed air was extracted from the intermediate stage of engine compressor. MATLAB software was used to simulate the engine cycle and estimate performance. The performance of (AI-BAS) was investigated computationally for different bleed air ratio. The computational domain was constructed and solved by ANSYS software for partial span model (PSM) with suitable periodic conditions. The obtained results show that the engine performance characteristics are decreased with increasing of anti-icing bleed air and the overall efficiency of engine is decreased by about 1.29%, 2.63% and 4.01%, for bleed air ratio of 0.02, 0.04 and 0.06 respectively. On the other hand, the average temperature of wing leading edge was increased by about 2.68% and 4.86%, for bleed air ratio of 0.04 and 0.06 respectively compared to the bleed air ratio of 0.02.

Effect of air properties on a twin-shaft turbofan engine performance during start-up

When engines start in coastal areas in summer, the performance of turbofan engine and starter will be inevitably affected by ambient humidity and temperature. It is important to predict the change of start-up performance by capturing the effect of ambient humidity and temperature on the matching process between turbofan engine and starter. However, in the start-up model, starter model is usually simplified by look-up table of starter power and semi-empirical formulas. It is difficult to simulate the variation of transient performance of turbofan engine caused by the power change of the starter when the ambient humidity and temperature increase. In this paper, a new method for simulating the transient performance of start-up process is presented. The nonlinear transient model including turbofan engine and starter is developed based on real engine configurations. The power compatibility equation is established to correlate the turbofan engine and starter to predict the matching performance in the start-up stage. The model is validated using mature commercial software. The steady-state errors of the model are within 2 % and the dynamic errors are within 2.5 %. In this paper, the start-up process is divided into four stages, and the transient performance of turbofan engine and starter in each stage is analyzed. This paper simulates the transient performance of start-up process under different ambient temperature and humidity conditions. The results show that when the ambient temperature is 308.5 K and the relative humidity is 0.8, the starter power is reduced by 76.86 % and the start-up time is increased by 10.28 s.

Turbofan engine performance prediction methodology integrated high-fidelity secondary air system models

This research studies the performance of an ultra-high bypass ratio turbofan engine, and specifically its secondary air system (SAS). A co-simulation methodology is explored whereby a high-fidelity SAS model and an engine performance code featuring flexible modules can be coupled and interactively executed. The percentage of bleed flows and boundary conditions for the SAS are updated at each iteration step. For this purpose, a SAS model including different elements is developed. Furthermore, a commercial computational fluid dynamics (CFD) solver is adopted to capture the complex flow field in the pre-swirl system. The credibility of cycle calculation and SAS elements is validated by comparing with publicly available data. Subsequently, an elaborately designed SAS is modeled and co-simulated with the AGTF30 engine using a flow network simulation method. The coupling effect between the engine performance and the SAS is studied for eight different flight conditions. The correlation and prediction of engine performance due to seal clearance change is presented. The co-simulation approach clarifies the mutual interactions between the engine overall parameters and the SAS. The results reveal that the enhanced flow network model can improve the simulation accuracy of engine performance over a wide range of operating conditions.

Energy and performance analysis of a turbofan engine with the aid of dynamic component efficiencies

Assessment of performance of turbofan engine with different design parameters is crucial for meeting the performance requirements by considering each key components of the engine. To comprehend influences of component efficiencies to mitigate environmental effect from turbofans has been hot topics in aviation field recently. In this study, firstly, impacts of polytropic efficiencies of fan, compressor and turbine as well as pressure ratio of combustor (CPR) on several turbofan performance are dealt with at several flight conditions. Secondly, it is tried to show difference of performance metrics under ideal and real conditions. The discrepancy between performance parameters computed at ideal and real cases gets relatively high. Namely, at take-off condition, the difference between ideal and real specific fuel consumption is computed as 29.12% whereas it is found as 28.37% at cruise condition, which shows that considering the system as ideal makes the computations inappropriate for performance analysis. Moreover, performance parameters of turbofan is more sensitive to compressor efficiency compared with turbine. As the polytropic efficiencies of fan and compressor are close to highest, net thrust of the engine develops from 109.05 kN (baseline) to 124.71 kN at take-off while it increases from 26.36 kN (baseline) to 29.27 kN at cruise condition. With effect of the elevated pressure ratio of combustor and efficiency of turbine, thrust of the engine increases to 118.23 kN at take off and to 27.84 kN at cruise condition. Finally, as Mach number increases, the difference between ideal and real performance values sharply increases. Therefore, when analyzing on turbofan engines, the assumptions should be minimum as possible as, otherwise the findings make the engineers to misguide for system optimization. Besides, these outcomes show that if the components with higher polytropic efficiency can be obtained, overall efficiency of turbofan, thereby environmental sustainability could be elevated to upper level compared with baseline.

Full-envelope acceleration control method of turbofan engine based on variable geometry compound adjustment

In order to reduce the influence of compressor stability margin constraint and enhance the full envelope acceleration performance of turbofan engine, a full envelope acceleration control method of turbofan engine based on variable compressor intermediate stage bleed and adjustable low-pressure (LP) turbine guide vane is proposed. Firstly, a high confidence turbofan engine component level model is established, which is capable of modifying the compressor adiabatic efficiency caused by variable intermediate stage bleed and adjusting the LP turbine guide vane adaptively. Then, the main combustion chamber fuel flow, compressor intermediate stage bleed flow and LP turbine guide vane angle are selected as the optimization variables. Meanwhile, the PSO-SQP (Particle Swarm Optimization-Sequential Quadratic Programming) method is adopted to obtain the acceleration compound control schedule. Finally, the full envelope compound adjustment acceleration control plan is available based on the similarity conversion theory of consistent engine inlet total temperature. The simulation results demonstrate that the acceleration control method based on variable geometry compound adjustment can significantly promote engine acceleration performance in the left flight envelope, shorten the maximum acceleration time by more than 50%, and dramatically improve the stability margin of the compressor during acceleration phase. In the right flight envelope, the variation law of the minimum surge margin during acceleration procedure almost coincides with the engine inlet isotherm. It proves that the method proposed possesses good applicability and feasibility in the full envelope.

Study on the Effect of Swallowing Birds on the Performance of Turbofan Engine

Study on the Effect of Swallowing Birds on the Performance of Turbofan Engine

Nonlinear Model Predictive Control-Based Optimal Energy Management for Hybrid Electric Aircraft Considering Aerodynamics-Propulsion Coupling Effects

Hybrid electric propulsion systems have been identified as feasible solutions for regional jets and narrow-body aircraft to reduce block fuel burn, emissions, and operating costs. In this article, a nonlinear model predictive control-based optimal energy management scheme (MPC-EMS) has been proposed to minimize the block fuel burn during flight. First, the artificial neural network (ANN) model is adopted to predict turbofan engine performance; meanwhile, gas turbine–electrical powertrain integration is investigated and analyzed for typical operating conditions. Then, by combining a point-mass aircraft dynamic model, nonlinear MPC with the cross-entropy method (CEM) is proposed to obtain optimal energy management based on a fully coupled aerodynamics-propulsion hybrid electric aircraft model. Besides, this state-constrained optimal control problem is reformulated as a state-unconstrained problem with a penalty function to reduce the computational load. Finally, the proposed MPC-EMS algorithm is applied to Boeing 737-800 aircraft with mechanically parallel hybrid electric propulsion configuration to minimize the block fuel burn and compared with the optimization results using global genetic algorithm (GA)-based EMS and equivalent consumption minimization strategy (ECMS). The simulation results indicate that the proposed MPC-EMS can effectively reduce the computational time compared with global GA-based EMS while achieving global optimization performance with only a minor difference of 1.71% of block fuel burn and emissions reductions.

Predicting the energy and exergy performance of F135 PW100 turbofan engine via deep learning approach

In the present study, the effects of flight-Mach number, flight altitude, fuel types, and intake air temperature on thrust specific fuel consumption, thrust, intake air mass flow rate, thermal and propulsive efficiecies, as well as the exergetic efficiency and the exergy destruction rate in F135 PW100 engine are investigated. Based on the results obtained in the first phase, to model the thermodynamic performance of the aforementioned engine cycle, Flight-Mach number and flight altitude are considered to be 2.5 and 30,000 m, respectively; due to the operational advantage of supersonic flying at high altitude flight conditions, and the higher thrust of hydrogen fuel. Accordingly, in the second phase, taking into account the mentioned flight conditions, an intelligent model has been obtained to predict output parameters (i.e., thrust, thrust specific fuel consumption, and overall exergetic efficiency) using the deep learning method. In the attained deep neural model, the pressure ratio of the high-pressure turbine, fan pressure ratio, turbine inlet temperature, intake air temperature, and bypass ratio are considered input parameters. The provided datasets are randomly divided into two sets: the first one contains 6079 samples for model training and the second set contains 1520 samples for testing. In particular, the Adam optimization algorithm, the cost function of the mean square error, and the active function of rectified linear unit are used to train the network. The results show that the error percentage of the deep neural model is equal to 5.02%, 1.43%, and 2.92% to predict thrust, thrust specific fuel consumption, and overall exergetic efficiency, respectively, which indicates the success of the attained model in estimating the output parameters of the present problem.

Effect of Air Properties on a Twin-Shaft Turbofan Engine Performance During Start-Up

Effect of Air Properties on a Twin-Shaft Turbofan Engine Performance During Start-Up

Effect of Air Properties on a Twin-Shaft Turbofan Engine Performance During Start-Up

Effect of Air Properties on a Twin-Shaft Turbofan Engine Performance During Start-Up

Numerical modeling on installed performance of turbofan engine with inlet ejector

In order to consider the capacity of aircraft infrared stealth, a turbofan engine with inlet ejector nozzle is derived for flight mission analysis. The turbofan engine is equipped with an auxiliary inlet door that utilizes the inlet bypass flow to ejector the nozzle and increase the engine installed thrust. Firstly, on the basis of the quasi one-dimensional flow theory, the ejector nozzle model is established to analyze its performance effect on the engine. Secondly, a backward infrared radiation intensity prediction method for exhaust system is proposed. Finally, during the analysis of engine installed performance, the supersonic inlet drag is considered. The numerical simulations results indicated that, compared with the conventional turbofan engine, the turbofan engine with inlet ejector not only reduces the infrared radiation and specific fuel consumption, but also increases the engine installed thrust, which improves the engine performance significantly.

Modeling Geared Turbofan and Open Rotor Engine Performance for Year-2050 Long-Range and Short-Range Aircraft

Abstract This paper provides design and performance data for two envisaged year-2050 engines: a geared high bypass turbofan for intercontinental missions and a contra-rotating pusher open rotor targeting short to medium range aircraft. It defines component performance and cycle parameters, general arrangements, sizes, and weights. Reduced thrust requirements reflect expected improvements in engine and airframe technologies. Advanced simulation platforms have been developed to model the engines and details of individual components. The engines are optimized and compared with “baseline” year-2000 turbofans and an anticipated year-2025 open rotor to quantify the relative fuel-burn benefits. A preliminary scaling with year-2050 “reference” engines, highlights tradeoffs between reduced specific fuel consumption (SFC) and increased engine weight and diameter. These parameters are converted into mission fuel burn variations using linear and nonlinear trade factors (NLTF). The final turbofan has an optimized design-point bypass ratio (BPR) of 16.8, and a maximum overall pressure ratio (OPR) of 75.4, for a 31.5% TOC thrust reduction and a 46% mission fuel burn reduction per passenger kilometer compared to the respective “baseline” engine–aircraft combination. The open rotor SFC is 9.5% less than the year-2025 open rotor and 39% less than the year-2000 turbofan, while the TOC thrust increases by 8% versus the 2025 open rotor, due to assumed increase in passenger capacity. Combined with airframe improvements, the final open rotor-powered aircraft has a 59% fuel-burn reduction per passenger kilometer relative to its baseline.

Modeling of the turbofan with an ejector nozzle based on infrared prediction

In order to study the effect of ejector nozzle on the overall performance of turbofan engine, a turbofan engine model with ejector nozzle is established in this paper, which includes parameter cycle analysis module and performance cycle analysis module. A backward prediction method of infrared radiation intensity for exhaust system is proposed, which includes solid wall and gas infrared radiation intensity prediction. The infrared characteristics and overall performance of the turbofan engine with ejector nozzle are analyzed and calculated in the flight missions. Firstly, the simulation model of turbofan engine with ejector nozzle is established and the influence of ejector bypass ratio on thrust performance of engine is studied. Secondly, the prediction model of engine infrared radiation intensity is established based on the prediction method of infrared radiation intensity. Finally, numerical simulations were carried out for different bypass ratios and different flight missions.

Vortical flow development in round ducts across scales for engine inlet applications

Turbofan engine performance depends highly on the characteristics and conditions of the inlet flow. Swirl distortions, caused by non-uniformities in flows arising from boundary layer or ground/fuselage vortex ingestion are of concern and need to be fully understood to guarantee efficiency and safety of propulsion systems. To investigate a fundamental single-vortex distortion development in a duct at different Reynolds numbers, a StreamVane distortion generating device was designed and experimentally analyzed in a small-scale low-speed wind tunnel (ReD 500,000) and in a full-scale engine testing rig (ReD 3 million). Stereoscopic particle image velocimetry was used to measure the three-component velocity fields at discrete measurement planes downstream of the distortion device. Results show that the secondary flow is generated and develops very similarly in both scales, and is mostly driven by two-dimensional (2D) vortex dynamics. Induced velocities arising from the proximity of the vortex to the duct wall causes the vortex center to convect circumferentially around the duct, in the same sense as the vortex rotation, as it travels downstream. Small-scale turbulence results show small-scale instabilities related to the development of the vortex. This work shows that the development of this vane-generated, vortex-dominated flow is largely Reynolds number independent for the covered range, so that details of similar duct-bounded flows can be analyzed in depth in small-scale experiments, decreasing development efforts and cost.

Turbofan engine performance optimization based on aircraft cruise thrust level

The aim of this paper is to define a methodology to minimize the adjustment effort required to comply with aircraft design performance requirements, when commercial off-the-shelf turbofan engines are installed, which is a challenge to aircraft manufactures. In order to achieve an efficient operation, a reasonable proposal is to adapt the propulsive performance by turbofan engine optimization. This work is carried out according to the following steps: (i) creation of estimated performance curves for a gas turbine from limited data; (ii) analysis of the impacts on performance and propulsive integration, applying computer simulation of the most promising engine components configuration; and (iii) matching between the lowest specific fuel consumption and the net thrust required for the cruise flight phase of the aircraft. The technical feasibility and the possible predisposition of engine manufactures to perform the implementation were also considered as critical points in this procedure. As a final result, an evaluation that presents the most suitable turbofan engine component modifications proposal to comply with engine/aircraft performance integration to be applied in the conceptual design phase was obtained.