Conceptual Design and Mission Analysis for a Geared Turbofan and an Open Rotor Configuration

In this multidisciplinary study a geared open rotor configuration is assessed and compared to an ultra high bypass ratio geared turbofan engine. Both designs assume a 2020 entry into service level of technology. The specific thrust level for minimizing block fuel and the resulting engine emissions for a given mission is sought. The tool used contains models that effectively capture: engine performance, mechanical and aerodynamic design, engine weight, emissions, aircraft design and performance as well as direct operating costs. The choice of specific thrust is a complex optimization problem and several disciplines need to be considered simultaneously. It will be demonstrated, through multidisciplinary analysis, that the open rotor concept can offer a substantial fuel saving potential, compared to ducted fans, for a given set of design considerations and customer requirements.

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

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4045077 ◽

2020 ◽

Vol 142 (4) ◽

Author(s):

Francesco S. Mastropierro ◽

Joshua Sebastiampillai ◽

Florian Jacob ◽

Andrew Rolt

Keyword(s):

Short Range ◽

Pressure Ratio ◽

Engine Performance ◽

Optimized Design ◽

Fuel Burn ◽

Medium Range ◽

Open Rotor ◽

And Performance ◽

Year 2000 ◽

Bypass Ratio

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.

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

Volume 1: Aircraft Engine; Fans and Blowers; Marine; Honors and Awards ◽

10.1115/gt2019-90775 ◽

2019 ◽

Author(s):

Joshua Sebastiampillai ◽

Florian Jacob ◽

Francesco S. Mastropierro ◽

Andrew Rolt

Keyword(s):

State Of The Art ◽

Pressure Ratio ◽

Engine Performance ◽

Fuel Burn ◽

Trade Offs ◽

Medium Range ◽

Open Rotor ◽

And Performance ◽

Year 2000 ◽

Bypass Ratio

Abstract The paper provides design and performance data for two envisaged year-2050 state-of-the-art 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 powerplant arrangements, sizes and weights. Reduced thrust requirements for future aircraft reflect expected improvements in engine and airframe technologies. Advanced simulation platforms have been developed, using the software PROOSIS, to model the engines and details of individual components, including custom elements for the open rotor engine. The engines are optimised and compared with ‘baseline’ year-2000 turbofans and an anticipated year-2025 entry-into-service open rotor to quantify the relative fuel-burn benefits. A preliminary scaling with non-optimised year-2050 ‘reference’ engines, based on Top-of-Climb (TOC) thrust and bypass ratio, highlights the trade-offs between reduced specific fuel consumption (SFC) and increased weight and engine diameter. These parameters are then converted into mission fuel burn using linear and non-linear trade factors from aircraft models. The final turbofan has an optimised 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 kilometre compared to the respective year-2000 baseline engine and aircraft combination. The final 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 aircraft passenger capacity. Combined with airframe improvements, the final open rotor-powered aircraft has a 59% fuel-burn reduction per passenger kilometre relative to its year-2000 baseline.

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Open Rotor Engine Cycle Modeling and Performance Assessment

Volume 1: Aircraft Engine; Fans and Blowers ◽

10.1115/gt2020-14563 ◽

2020 ◽

Author(s):

Ziyu Zhang ◽

Li Zhou ◽

Xiaobo Zhang ◽

Zhanxue Wang

Keyword(s):

Engine Performance ◽

Performance Model ◽

Civil Aviation ◽

Environment Impact ◽

Turbine Performance ◽

New Concepts ◽

Open Rotor ◽

Potential Impact ◽

And Performance ◽

Bypass Ratio

Abstract Aiming to enable dramatic reductions in the environment impact and fuel consumption of future civil aviation, NASA and European related research institutions are committed to developing new concepts and technologies in which counter rotating open rotor (CROR) concept can achieve this objective. In order to evaluate its potential impact, an open rotor engine performance model needs to be established. This paper presents the modeling method of an open rotor engine with the geared counter rotating open rotor (GOR) as object, and implements it in an in-house modular program of gas turbine performance prediction. In addition, the steady-state performance of the model is analyzed, and the model accuracy is verified based on the existing data. On this basis, the performance of open rotor engine and high bypass ratio turbofan engine is compared and results show that the counter rotating open rotor engine has obvious fuel saving advantages.

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CFD Study of Nozzle Configurations for Ultra High Bypass Engines

Volume 3C: General ◽

10.1115/93-gt-389 ◽

1993 ◽

Cited By ~ 1

Author(s):

H. Zimmermann ◽

R. Gumucio ◽

K. Katheder ◽

A. Jula

Keyword(s):

Engine Performance ◽

Operating Conditions ◽

Aerodynamic Design ◽

Thrust Coefficient ◽

Optimum Range ◽

Installation Effects ◽

Wide Range ◽

And Performance ◽

Aircraft Aerodynamics ◽

Bypass Ratio

Performance and aerodynamic aspects of ultra-high bypass ratio ducted engines have been investigated with an emphasis on nozzle aerodynamics. The interference with aircraft aerodynamics could not be covered. Numerical methods were used for aerodynamic investigations of geometrically different aft end configurations for bypass ratios between 12 and 18, this is the optimum range for long missions which will be important for future civil engine applications. Results are presented for a wide range of operating conditions and effects on engine performance are discussed. The limitations for higher bypass ratios than 12 to 18 do not come from nozzle aerodynamics but from installation effects. It is shown that using CFD and performance calculations an improved aerodynamic design can be achieved. Based on existing correlations, for thrust and mass-flow, or using aerodynamic tailoring by CFD and including performance investigations, it is possible to increase the thrust coefficient up to 1%.

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Numerical Simulation of Propulsion System Integration for Very High Bypass Ratio Engines

Volume 1: Aircraft Engine; Ceramics; Coal, Biomass and Alternative Fuels; Controls, Diagnostics and Instrumentation ◽

10.1115/gt2012-68908 ◽

2012 ◽

Cited By ~ 1

Author(s):

Thierry Sibilli ◽

Mark Savill ◽

Vishal Sethi ◽

David MacManus ◽

Andrew M. Rolt

Keyword(s):

System Integration ◽

New Technologies ◽

Engine Performance ◽

Aircraft Design ◽

Aircraft Engine ◽

Fuel Burn ◽

Active Core ◽

Core Concepts ◽

Work Programme ◽

Bypass Ratio

Due to a trend towards Ultra High Bypass Ratio engines, confirmed in projects like NEWAC (New Aero Engine Core Concepts, an European Sixth Frame Work Programme) the corresponding engine/airframe interference is becoming a key aspect in aircraft design. Therefore detailed aerodynamic investigations are required to evaluate the real benefits of these new technologies. The work presented in this paper is to perform these investigations for two typical twin-engine/low-wing transports, using Computational Fluid Dynamics, in order to create a useful integration module for the in-house aircraft/engine performance software TERA2020 (Techno-economic Environmental and Risk Assessment for 2020). The paper presents results for two NEWAC engines: Intercooled Core Long Range (IC L/R) and the Active Core Short Range (AC S/R). The main results show that the engine horizontal positioning can influence mission fuel burn by up to 6.4% for AC S/R and 3.7% for IC L/R respectively.

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Performance prediction and progress towards multi-disciplinary design of contra-rotating open rotors

The Aeronautical Journal ◽

10.1017/s0001924000009830 ◽

2014 ◽

Vol 118 (1208) ◽

pp. 1159-1179 ◽

Cited By ~ 2

Author(s):

S. Guérin ◽

R. Schnell ◽

R. G. Becker

Keyword(s):

Experimental Data ◽

Wind Tunnel ◽

Environmental Impact ◽

Performance Prediction ◽

Engine Performance ◽

Turbofan Engines ◽

Prediction Tools ◽

First Results ◽

Open Rotor ◽

Bypass Ratio

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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Design Study for a Fuel Efficient Turbofan Engine

Volume 1B: General ◽

10.1115/80-gt-141 ◽

1980 ◽

Author(s):

R. C. Kingcombe ◽

S. W. Dunning

Keyword(s):

Pressure Ratio ◽

Operating Cost ◽

Engine Performance ◽

Design Study ◽

Technological Advances ◽

Engine Design ◽

Direct Operating Cost ◽

Specific Thrust ◽

The One ◽

Bypass Ratio

An engine design study is presented in which the target is a 15 percent reduction in installed specific fuel consumption over the large engines currently in service while still meeting anticipated noise and emissions regulations. The fuel saving is achieved with a low specific thrust (bypass ratio 10) and a high overall cycle pressure ratio (42 at cruise). A three-shaft design is proposed, employing highly loaded components in order to reduce the number of turbomachinery stages and hence keep down cost and weight. It is argued that this approach is the one most compatible with projected technological advances. The engine configuration is given and the key features explained, highlighting areas where further research would be of particular advantage. Finally, the predicted engine performance is given, together with an estimate of the savings in direct operating cost.

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State of Art of Using Biofuels in Spark Ignition Engines

Energies ◽

10.3390/en14030779 ◽

2021 ◽

Vol 14 (3) ◽

pp. 779

Author(s):

Ashraf Elfasakhany

Keyword(s):

Engine Performance ◽

Spark Ignition ◽

Pollutant Emissions ◽

Spark Ignition Engines ◽

Engine Emissions ◽

Cold Starting ◽

Starting Conditions ◽

Unburned Hydrocarbons ◽

Scientific Attention ◽

State Of Art

Biofuels are receiving increased scientific attention, and recently different biofuels have been proposed for spark ignition engines. This paper presents the state of art of using biofuels in spark ignition engines (SIE). Different biofuels, mainly ethanol, methanol, i-butanol-n-butanol, and acetone, are blended together in single dual issues and evaluated as renewables for SIE. The biofuels were compared with each other as well as with the fossil fuel in SIE. Future biofuels for SIE are highlighted. A proposed method to reduce automobile emissions and reformulate the emissions into new fuels is presented and discussed. The benefits and weaknesses of using biofuels in SIE are summarized. The study established that ethanol has several benefits as a biofuel for SIE; it enhanced engine performance and decreased pollutant emissions significantly; however, ethanol showed some drawbacks, which cause problems in cold starting conditions and, additionally, the engine may suffer from a vapor lock situation. Methanol also showed improvements in engine emissions/performance similarly to ethanol, but it is poisonous biofuel and it has some sort of incompatibility with engine materials/systems; its being miscible with water is another disadvantage. The lowest engine performance was displayed by n-butanol and i-butanol biofuels, and they also showed the greatest amount of unburned hydrocarbons (UHC) and CO emissions, but the lowest greenhouse effect. Ethanol and methanol introduced the highest engine performance, but they also showed the greatest CO2 emissions. Acetone introduced a moderate engine performance and the best/lowest CO and UHC emissions. Single biofuel blends are also compared with dual ones, and the results showed the benefits of the dual ones. The study concluded that the next generation of biofuels is expected to be dual blended biofuels. Different dual biofuel blends are also compared with each other, and the results showed that the ethanol–methanol (EM) biofuel is superior in comparison with n-butanol–i-butanol (niB) and i-butanol–ethanol (iBE).

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Rotor Interaction Noise in Counter-Rotating Propfan Propulsion Systems

Journal of Turbomachinery ◽

10.1115/1.4003223 ◽

2011 ◽

Vol 134 (1) ◽

Cited By ~ 16

Author(s):

Andreas Peters ◽

Zoltán S. Spakovszky

Keyword(s):

Polar Angle ◽

Secondary Flows ◽

Tip Vortex ◽

System Level ◽

Analysis Tool ◽

Acoustic Analogy ◽

Wake Interaction ◽

Open Rotor ◽

And Performance ◽

The Individual

Due to their inherent noise challenge and potential for significant reductions in fuel burn, counter-rotating propfans (CRPs) are currently being investigated as potential alternatives to high-bypass turbofan engines. This paper introduces an integrated noise and performance assessment methodology for advanced propfan powered aircraft configurations. The approach is based on first principles and combines a coupled aircraft and propulsion system mission and performance analysis tool with 3D unsteady, full-wheel CRP computational fluid dynamics computations and aeroacoustic simulations. Special emphasis is put on computing CRP noise due to interaction tones. The method is capable of dealing with parametric studies and exploring noise reduction technologies. An aircraft performance, weight and balance, and mission analysis was first conducted on a candidate CRP powered aircraft configuration. Guided by data available in the literature, a detailed aerodynamic design of a pusher CRP was carried out. Full-wheel unsteady 3D Reynolds-averaged Navier-Stokes (RANS) simulations were then used to determine the time varying blade surface pressures and unsteady flow features necessary to define the acoustic source terms. A frequency domain approach based on Goldstein’s formulation of the acoustic analogy for moving media and Hanson’s single rotor noise method was extended to counter-rotating configurations. The far field noise predictions were compared to measured data of a similar CRP configuration and demonstrated good agreement between the computed and measured interaction tones. The underlying noise mechanisms have previously been described in literature but, to the authors’ knowledge, this is the first time that the individual contributions of front-rotor wake interaction, aft-rotor upstream influence, hub-endwall secondary flows, and front-rotor tip-vortices to interaction tone noise are dissected and quantified. Based on this investigation, the CRP was redesigned for reduced noise incorporating a clipped rear-rotor and increased rotor-rotor spacing to reduce upstream influence, tip-vortex, and wake interaction effects. Maintaining the thrust and propulsive efficiency at takeoff conditions, the noise was calculated for both designs. At the interaction tone frequencies, the redesigned CRP demonstrated an average reduction of 7.25 dB in mean sound pressure level computed over the forward and aft polar angle arcs. On the engine/aircraft system level, the redesigned CRP demonstrated a reduction of 9.2 dB in effective perceived noise (EPNdB) and 8.6 EPNdB at the Federal Aviation Regulations (FAR) 36 flyover and sideline observer locations, respectively. The results suggest that advanced open rotor designs can possibly meet Stage 4 noise requirements.

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