scholarly journals ОСОБЕННОСТИ РАСЧЕТА И РЕГУЛИРОВАНИЯ ДВУХКОНТУРНОГО ТУРБОРЕАКТИВНОГО ДВИГАТЕЛЯ С ФОРСАЖНОЙ КАМЕРОЙ СГОРАНИЯ В НАРУЖНОМ КОНТУРЕ НА ПРЯМОТОЧНЫХ РЕЖИМАХ РАБОТЫ

2020 ◽  
pp. 15-23
Author(s):  
Олег Владимирович Кислов ◽  
Михаил Анатольевич Шевченко
Keyword(s):  
Mathematical Model ◽  
Fuel Consumption ◽  
Control Program ◽  
Critical Section ◽  
Specific Fuel Consumption ◽  
Outlet Section ◽  
Nozzle Outlet ◽  
Turbofan Engine ◽  
Turbofan Engines ◽  
Ramjet Engines

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.

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.

Optimizing Separate Exhaust Turbofans for Cruise Specific Fuel Consumption

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Syed J. Khalid
Keyword(s):  
Fuel Consumption ◽  
Control Algorithm ◽  
Velocity Ratio ◽  
Transmission Efficiency ◽  
Specific Fuel Consumption ◽  
Variable Geometry ◽  
Nozzle Throat ◽  
Propulsive Efficiency ◽  
Turbofan Engines ◽  
Bypass Ratio

Cruise specific fuel consumption (SFC) of turbofan engines is a key metric for increasing airline profitability and for reducing CO2 emissions. Although increasing design bypass ratio (BPR) of separate exhaust turbofan configurations improves cruise SFC, further improvements can be obtained with online control actuated variable geometry modulations of bypass nozzle throat area, core nozzle throat area, and compressor variable vanes (CVV/CVG). The scope of this paper is to show only the benefits possible, and the process used in determining those benefits, and not to suggest any particular control algorithm for searching the best combination of the control effectors. A parametric cycle study indicated that the effector modulations could increase the cruise BPR, core efficiency, transmission efficiency, propulsive efficiency, and ideal velocity ratio resulting in a cruise SFC improvement of as much as 2.6% depending upon the engine configuration. The changes in these metrics with control effector variations will be presented. Scheduling of CVV is already possible in legacy digital controls; perturbation to this schedule and modulation of nozzle areas should be explored in light of the low bandwidth requirements at steady-state cruise conditions.

Advanced Turbofan Engines for Low Fuel Consumption

1978 ◽  
Author(s):  
William Sens
Keyword(s):  
Fuel Consumption ◽  
Advanced Technology ◽  
Commercial Aircraft ◽  
New Production ◽  
Turbofan Engine ◽  
Fuel Savings ◽  
Turbofan Engines ◽  
Aircraft Fuel ◽  
Design Characteristics ◽  
Year 2000

The anticipated commercial aircraft fuel usage through the year 2000 is divided into three categories: that which will be consumed by existing engines, new production of current type engines, and new turbofan engines with advanced technology. Means of improving fuel consumption of each of these engine categories will be reviewed and the potential fuel savings identified. The cycle selection and design characteristics of an advanced turbofan engine configuration will be discussed and the potential improvements in fuel consumption and economics identified.

Feasibility Study of Some Novel Concepts for High Bypass Ratio Turbofan Engines

2009 ◽  
Author(s):  
Dipanjay Dewanji ◽  
G. Arvind Rao ◽  
Jos van Buijtenen
Keyword(s):  
Fuel Consumption ◽  
Substantial Reduction ◽  
Substantial Improvement ◽  
Fuel Price ◽  
Turbofan Engine ◽  
Turbofan Engines ◽  
Fuel Flow ◽  
Blade Tip ◽  
Fan Blade ◽  
Bypass Ratio

The soaring fuel price and the burgeoning environmental concerns have compelled global research towards cleaner engines, aimed at substantial reduction in emission, noise and fuel consumption. In this context, the present research investigates the feasibility of some novel engine concepts, namely Geared Turbofan and Intercooled Recuperated Turbofan concepts, by hypothetically applying them into an existing state-of-the-art high bypass ratio engine. This paper made an effort to estimate the effects on the baseline engine performances due to the introduction of these two concepts into it. By performing steady state simulations, it was found that the incorporation of the Geared Turbofan concept into the existing Turbofan engine caused a significant reduction in thrust specific fuel consumption, engine weight, and fan blade tip speed. However, when simulations were also carried out by incorporating the Intercooler and Recuperator concept in the baseline turbofan engine, it did not demonstrate any substantial improvement in fuel consumption. It was observed that the fuel flow rate was influenced to a large extent by heat exchanger’s effectiveness and the pressure drop within it. The overall engine weight was also found to get increased due to the inclusion of massive heat exchangers necessary for the system.

Optimizing Separate Exhaust Turbofans for Cruise Specific Fuel Consumption

2016 ◽  
Author(s):  
Syed Khalid
Keyword(s):  
Fuel Consumption ◽  
Control Algorithm ◽  
Velocity Ratio ◽  
Transmission Efficiency ◽  
Specific Fuel Consumption ◽  
Variable Geometry ◽  
Nozzle Throat ◽  
Propulsive Efficiency ◽  
Turbofan Engines ◽  
Bypass Ratio

Cruise specific fuel consumption (SFC) of turbofan engines is a key metric for increasing airline profitability and for reducing CO2 emissions. Although increasing design bypass ratio (BPR) of separate exhaust turbofan configurations improves cruise SFC, further improvements can be obtained with control actuated variable geometry modulations of core nozzle throat area, bypass nozzle throat area, and compressor variable vanes (CVV). The scope of this paper is to show only the benefits possible, and the process used in determining those benefits, and not to suggest any particular control algorithm for searching the best combination of the control effectors. A parametric cycle study indicated that the effector modulations could increase the cruise BPR, core efficiency, transmission efficiency, propulsive efficiency, and ideal velocity ratio resulting in a cruise SFC improvement of as much as 2.6% depending upon the engine configuration. The changes in these metrics with control effector variations will be presented. Modulation of CVV is already possible in legacy digital controls, and modulation of nozzle areas should be explored in light of the low bandwidth requirements at steady-state cruise conditions.

Altitude Engine Test of a Turbofan Exhaust Gas Mixer to Conserve Fuel

1977 ◽  
Vol 99 (4) ◽  
pp. 645-649 ◽  
Author(s):  
R. R. Cullom ◽  
R. L. Johnsen
Keyword(s):  
Fuel Consumption ◽  
Specific Fuel Consumption ◽  
Exhaust Gas ◽  
Engine Test ◽  
Turbofan Engine ◽  
Test Conditions ◽  
Total Temperature ◽  
Internal Mixer ◽  
Bypass Ratio ◽  
Fuel Consumption Improvement

A comparison of the specific fuel consumption was made with and without an internal mixer installed in a low bypass ratio, confluent flow turbofan engine. Tests were conducted at several Mach numbers and altitudes for core to fan stream total temperature ratios of 2.0 and 2.5 and mixing lengths of L/D = 0.95 and 1.74. For these test conditions, the specific fuel consumption improvement varied from 2.5 to 4.0 percent.

Conceptual Study of Counter-Rotating Turbofan Engines

2010 ◽  
Author(s):  
Ne´stor Gonza´lez Di´ez ◽  
Arvind G. Rao ◽  
Jos van Buijtenen
Keyword(s):  
Fuel Consumption ◽  
Pressure Ratio ◽  
Single Stage ◽  
Specific Fuel Consumption ◽  
Advisory Council ◽  
Similar Amount ◽  
Noise Emission ◽  
Turbofan Engines ◽  
Conceptual Study ◽  
Semi Empirical

The dramatic growth that air traffic has experienced in the last years is not likely to slow down in the future. The situation for the airlines has however been critical due to the large share of the operating costs corresponding to fuel. On the other hand, the society demands quieter aircraft which is then translated into stricter regulations. The Advisory Council for Aeronautics Research in Europe (ACARE) has set an ambitious array of objectives to be accomplished by 2020. It is often claimed that complying with those targets will not require evolution but, rather, revolution. One of the potential future engine configurations being considered is the counter-rotating turbofan (CRTF) concept. This paper addresses the possibilities of improvement that the CRTF can offer with respect to the specific fuel consumption, emissions and noise as compared to the baseline engine, the GE90. Semi-empirical correlations and methodologies have been used for the study. First a Blade Element Method (BEM) is developed to estimate the performance of the fan and to build confidence upon the applied loss and deviation angle models. Next, the design methodology is applied to three cases: a single-stage fan featuring the reference properties of the GE90 engine; a counter-rotating fan (CRF) fan with similar properties as a GE90 fan, but with a lower rotational speed; and a CRF with higher fan pressure ratio (FPR) for lower specific fuel consumption. Finally, noise emission by all the three configurations are estimated by noise models available in the literature. Reductions of equivalent perceived noise level (EPNL) were found to be possible if a CRF is used instead of the baseline single-stage arrangement. Other noise descriptors are also reduced by a similar amount. Approximately equal noise levels are expected if the CRF is of higher pressure than the baseline.

scholarly journals Transport category airplane flight range calculation accounting center-of-gravity position shift and engine throttling characteristics

2021 ◽  
pp. 4-14
Author(s):  
Ruslan Tsukanov ◽  
Viktor Riabkov
Keyword(s):  
Mathematical Model ◽  
Fuel Consumption ◽  
Program Implementation ◽  
Fuel Efficiency ◽  
Real Data ◽  
Center Of Gravity ◽  
Specific Fuel Consumption ◽  
Flight Range ◽  
Position Shift ◽  
Range Calculation

A problem facing world commercial aviation is a provision of the flight range and an increase in the fuel efficiency of transport category airplanes using fuel trim transfer application, which allows for decreasing airplane trim drag at cruise flight. In the existing mathematical models, center-of-gravity position is usually assumed fixed, but with fuel usage, center-of-gravity shifts within the definite range of center-of-gravity positions. Until the fuel trim transfer was not used in airplanes, the center-of-gravity shift range was rather short, that allowed to use the specified assumption without any considerable mistakes. In case of fuel trim transfer use, center-of-gravity shifts can reach 15…20 % of mean aerodynamic chord, that requires considering the center-of-gravity actual position during the flight range calculation. Early made estimated calculations showed the necessity of following mathematical model improvement using accounting the real engine throttling characteristics. The goal of this publication is to develop a method of flight range calculation taking transport category airplane into account actual center-of-gravity position with fuel using and variation in engine-specific fuel consumption according to their throttling characteristics. On the basis of real data from engine maintenance manuals, formulas are obtained for approximation throttling characteristics of turbofan engines in the form of dimensionless specific fuel consumption (related to the specific fuel consumption at full thrust) dependence on the engine throttling coefficient. A mathematical model (algorithm and its program implementation using С language in Power Unit 11.7 R03 system) has been developed to calculate the airplane flight range accounting its actual center-of-gravity position shift with fuel usage and variation in specific fuel consumption according to engine throttling characteristics. Using comparison with known payload-range diagram, adequacy of developed mathematical model is shown. Recommendations to improve the mathematical model are also given.

scholarly journals Development of a method to improve the calculation accuracy of specific fuel consumption for performance modeling of air-breathing engines

2021 ◽  
Vol 2 (8 (110)) ◽  
pp. 23-30
Author(s):  
Oleh Kislov ◽  
Maya Ambrozhevich ◽  
Mykhailo Shevchenko
Keyword(s):  
Heat Capacity ◽  
Fuel Consumption ◽  
Estimation Error ◽  
Engine Performance ◽  
Isobaric Heat Capacity ◽  
Specific Fuel Consumption ◽  
Calculation Error ◽  
Turbofan Engine ◽  
Air Breathing

Determination of specific fuel consumption of air-breathing engines is one of the problems of modeling their performance. As a rule, the estimation error of the specific fuel consumption while calculating air-breathing engine performance is greater than that of thrust. In this work, this is substantiated by the estimation error of the fuel-air ratio, which weakly affects thrust but significantly affects the specific fuel consumption. The presence of a significant error in the fuel-air ratio is explained by the use of simplified methods, which use the dependence of enthalpy as a function of mixture temperature and composition without taking into account the effect of pressure. The developed method to improve the calculation accuracy of specific fuel consumption of air-breathing engines is based on the correction of the fuel-air ratio in the combustor, determined by the existing mathematical models. The correction of the fuel-air ratio is made using the dependences of enthalpy on mixture temperature, pressure and composition. The enthalpy of the mixture is calculated through the average isobaric heat capacity obtained by integrating the isobaric heat capacity, depending on mixture temperature, pressure and composition. The calculation accuracy of the fuel-air ratio was verified by comparing it with the known experimental data on the combustion chamber of the General Electric CF6-80A engine (USA). The average calculation error of the fuel-air ratio does not exceed 3 %. The developed method was applied for correcting the specific fuel consumption for calculating the altitude-airspeed performance of the D436-148B turbofan engine (Ukraine), which made it possible to reduce the estimation error of the fuel-air ratio and specific fuel consumption to an average of 3 %

Cycle Optimization of Mixed High Bypass Turbofan

2014 ◽  
Author(s):  
Adel Ghenaiet
Keyword(s):  
Fuel Consumption ◽  
Engine Performance ◽  
Feasibility Studies ◽  
Specific Fuel Consumption ◽  
Design Parameters ◽  
Optimization Approach ◽  
Propulsive Efficiency ◽  
Turbofan Engines ◽  
Passenger Aircraft ◽  
Analytical Expressions

This paper presents a parametric study and an optimization approach, targeting the design of optimum mixed turbofan engines employed by long-range passenger aircraft. The first part of this paper concerns a parametric analysis carried out with the aim of highlighting the effects of principal design criteria on engine performance in terms of specific thrust and specific fuel consumption. The second part deals with the optimization to find the design parameters concurrently minimizing the specific fuel consumption at cruise. The backbone of the optimization approach consists of a genetic algorithm and a developed engine performance analysis method for both design point and off-design operations. This latter employs closed form analytical expressions instead of numerical solution using pre-defined components’ maps. This approach is deemed sufficient for simple feasibility studies carried out during the course of conceptual and preliminary designs. The strong coupling between the core and bypass streams has constrained the range of physical properties and reduced the space of search for the optimum. The results show possible benefits from utilizing the mixing of gases and a common propelling nozzle, which in some cases may increase the propulsive efficiency.

Sign in / Sign up

Export Citation Format

Share Document