Effect of Bypass Ratio on Optimal Fan Outer Pressure Ratio and Performance for Turbofan Engines

2019 ◽  
Vol 20 (1) ◽  
pp. 157-164 ◽  
Author(s):  
Rui Xue ◽  
Jun Jiang ◽  
Anthony Jackson
Keyword(s):  
Pressure Ratio ◽  
Turbofan Engines ◽  
And Performance ◽  
Bypass Ratio

Optimum Cycle Parameters for Turbofan Engines

1970 ◽  
Author(s):  
W. C. Moffatt
Keyword(s):  
Simple Procedure ◽  
Pressure Ratio ◽  
Inlet Temperature ◽  
Closed Form Solutions ◽  
Turbofan Engines ◽  
Compressor Pressure Ratio ◽  
Temperature Component ◽  
Flow Through ◽  
Specific Thrust ◽  
Bypass Ratio

This paper presents closed-form solutions for optimum compressor pressure ratio, bypass ratio and fan pressure ratio, given the turbine inlet temperature, component efficiencies and flight Mach number for a turbofan engine. In addition a simple procedure is outlined for obtaining the optimum combination of these quantities and a sample calculation is included. The optimum condition is defined as that which maximizes the specific thrust (thrust per pound per second of air flow through the gasifier) of the engine. The effects of differing gas properties in different portions of the engine are included in the analysis.

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

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.

Generalized Optimization of Counter-Rotating and Single-Rotating Fans

2014 ◽  
Author(s):  
Timea Lengyel-Kampmann ◽  
Christian Voß ◽  
Eberhard Nicke ◽  
Klaus-Peter Rüd ◽  
Reinhold Schaber
Keyword(s):  
Global Optimization ◽  
Mach Number ◽  
Entire Range ◽  
Total Pressure ◽  
Pressure Ratio ◽  
Axial Fan ◽  
Turbofan Engines ◽  
Optimization Study ◽  
Bypass Ratio ◽  
Total Pressure Ratio

On possible fan concept for future high and ultra-high bypass ratio turbofan engines is the counter-rotating (CR) fan. Several studies [1][2][3][4] dealt already with the optimization of CR fans, however the mass flow and the total pressure ratio were typically given and fixed for a specified application. The results of these studies showed a benefit of the CR fan compared to the conventional single-rotating (SR) fan, which strongly depended on the engine cycle. Following this experience, it was necessary to further specify the efficiency benefits more precisely in association with fan total pressure ratio and fan inlet axial Mach number. The results are discussed in this present paper. A special emphasis was given on determining the optimal pressure ratio, for which the CR-fan expectably achieves the maximal efficiency benefit. The idea was to perform a global optimization study without any constraints for the operating point inside of a broad (ΠFan, Max) –range, for the rotational speeds and with only a few constraints for the geometry of the blades to avoid infeasible geometries. An adequate range for the fan pressure ratio (ΠFan) and for the axial Mach number (Max) was chosen for the global optimization covering the entire range from current to potential future ultra-high bypass ratio engine applications, also taking into account a reduced nacelle diameter and thus high axial fan inflow Mach numbers. The focus of the present study was to develop a method for the global optimization of a fan stage. As a result of this study, the maximal achievable efficiency is shown as a function of the fan pressure ratio and the axial Mach number. Thus the efficiency differences between the CR and SR fan can be calculated through the differences between the surfaces for any given set of parameters defining a potential engine. This allows for a generalized assessment of this particular fan concept over the entire range of relevant applications.

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

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.

scholarly journals Study of Bypass Ratio Increasing Possibility for Turbofan Engine and Turbofan with Inter Turbine Burner

2019 ◽  
Vol 26 (2) ◽  
pp. 61-68
Author(s):  
Robert Jakubowski
Keyword(s):  
Fuel Consumption ◽  
Energy Input ◽  
Pressure Ratio ◽  
Specific Fuel Consumption ◽  
Additional Energy ◽  
Fast Analysis ◽  
Turbofan Engine ◽  
Turbofan Engines ◽  
Specific Thrust ◽  
Bypass Ratio

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.

scholarly journals Making Turbofan Engines More Energy Efficient

1978 ◽  
Author(s):  
M. C. Hemsworth ◽  
M. A. Zipkin
Keyword(s):  
Energy Efficient ◽  
Pressure Ratio ◽  
Cost Effective ◽  
Substantial Improvement ◽  
Turbine Engine ◽  
Turbofan Engines ◽  
Trade Offs ◽  
Parametric Data ◽  
Bypass Ratio ◽  
Development And Evolution

A review of transport aircraft gas turbine engine development and evolution during the past two decades is presented in terms of energy consumption. The interaction and effects of cycle pressure ratio, firing temperature, bypass ratio, and component efficiencies on installed fuel consumption are reviewed. The possibilities for further substantial improvement in energy efficiency with improved operating economics and with improved environmental characteristics are identified and evaluated. Parametric data are presented showing trade-offs in the areas of efficiency and economics. Environmental considerations are also discussed. The balance of these factors in a cost-effective advanced turbofan is discussed. In conclusion, projections are made for the capability of an advanced turbofan engine compared with the goals established by NASA for their Energy Efficient Engine Program. The characteristics of this more efficient, cost-effective power plant, that can be operational in the late 1980’s, are shown in relationship to current turbofan engines.

scholarly journals Evaluation of ultra-high bypass ratio engines for an over-wing aircraft configuration

2018 ◽  
Vol 2 ◽  
pp. 493-515 ◽  
Author(s):  
Daniel Giesecke ◽  
Marcel Lehmler ◽  
Jens Friedrichs ◽  
Jason Blinstrub ◽  
Lothar Bertsch ◽  
...  
Keyword(s):  
Pressure Ratio ◽  
Safety Margin ◽  
Operating Costs ◽  
Research Centre ◽  
Turbofan Engines ◽  
Noise Shielding ◽  
Noise Benefits ◽  
Point To Point ◽  
Regional Airports ◽  
Bypass Ratio

Today, main hub airports are already at their capacity limit and hence, smaller airports have become more interesting for providing point-to-point connections. Unfortunately, the use of regional airports induces an increased environmental footprint for the population living around it. In an attempt to solve the related problems, the research project Coordinated Research Centre 880 aims to examine the fundamentals of a single-aisle aircraft with active high-lift configuration powered by two geared ultra-high bypass turbofan engines mounted over the wing. Low direct operating costs, noise shielding due to the over-wing configuration, and short runway lengths are the main advantages. Highlighting the performance, economical and noise benefits of a geared ultra-high bypass engine is the key aim of this paper. This assessment includes a correspondingly adjusted aircraft. Open literature values are applied to design the two investigated bypass ratios; a reference engine with a bypass ratio of 5 and 17 respectively. This study shows that a careful selection of engine mass flow, turbine entry temperature and overall pressure ratio determines the desirable bypass ratio. The aircraft direct operating costs drop by 5.7% when comparing the designed conventional with a future ultra-high bypass ratio engine. Furthermore, the sound at source for a selected mission and operating condition can be reduced by 7 dB. A variable bypass nozzle area for the ultra-high bypass ratio engine is analysed in terms of performance and operability. An increase of safety margin is shown for the turbofan engine with a variable bypass nozzle. It is concluded that this unconventional aircraft configuration with ultra-high bypass ratio engines mounted over the wing has the potential to relieve main hub airports and reduce the environmental impact.

An Evaluation of the Geometry and Weight of a Mixed Flow Low Bypass Ratio Turbofan Engine With an Intermediate Turbine Burner

2005 ◽  
Author(s):  
Chorng-Yow Chen ◽  
Mark H. Waters ◽  
Dimitri Mavris
Keyword(s):  
Mechanical Design ◽  
Pressure Ratio ◽  
Flow Path ◽  
Mixed Flow ◽  
Turbofan Engine ◽  
Turbofan Engines ◽  
Low Pressure Turbine ◽  
The Subject ◽  
Specific Thrust ◽  
Bypass Ratio

Turbofan engines are designed with two or even three spools of fan- compressor and turbine combinations. This arrangement allows the possibility of increased power output by placing a second combustor between turbine spools. Such a combustor is called an “Intermediate Turbine Burner, ITB,” and in a twin spool turbofan engine the combustor would be placed between the discharge of the high pressure turbine and the entrance of the low pressure turbine. An evaluation of the mechanical design of an ITB integrated into a low bypass ratio mixed flow turbofan is the subject of this paper. It is well known that an engine with an ITB has increased specific thrust but at the expense of increased specific fuel consumption. To take advantage of the ITB potential, the choice of cycle parameters — fan pressure ratio, overall pressure ratio and bypass ratio must be evaluated, and recent studies have demonstrated that the turbofan cycle with an ITB should have increased fan and overall pressure ratios to maximize performance. However, little has been done to estimate the weight and dimensions of an ITB integrated engine including the weight, flow path area and length of the ITB. Of particular concern are the volume and resulting flow path area and length required for the ITB.

Experimental research on the performance of the forward variable area bypass injector for variable cycle engines

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Binglong Zhang ◽  
He Liu ◽  
Jianhua Zhou ◽  
Hui Liu
Keyword(s):  
Pressure Ratio ◽  
Effective Means ◽  
Experimental System ◽  
Area Ratio ◽  
Back Pressure ◽  
Mode Transition ◽  
Bypass Valve ◽  
Injection Coefficient ◽  
Bypass Ratio ◽  
Specific Working

AbstractThe forward variable area bypass injector (FVABI) is a key component of double bypass variable cycle engine (VCE) to achieve mode transition and bypass ratio adjustment. In this paper, an experimental system for FVABI was constructed based on the analysis of relevant experimental theories, and then the experiments on FVABI were carried out for a specific working state in double bypass mode of VCE and for the comparison working states with different area ratios and different back pressure ratios. The results showed that the FVABI designed in this paper meets the requirements of VCE at this working state. The analysis of the influence of area ratio and back pressure ratio on the injection coefficient showed that the first bypass valve and back pressure were effective means to control the mass flow of FVABI.

scholarly journals CFD Study of Nozzle Configurations for Ultra High Bypass Engines

1993 ◽  
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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