scholarly journals The Potential of Sequential Combustion for High Bypass Jet Engines

1998 ◽  
Author(s):  
Konrad Vogeler
Keyword(s):  
Fuel Consumption ◽  
Specific Fuel Consumption ◽  
Maximum Pressure ◽  
Jet Engines ◽  
Gas Temperature ◽  
Core Mass ◽  
New Family ◽  
Fuel Flow ◽  
Lp Turbine ◽  
Bypass Ratio

ABB has designed a new family of industrial gasturbines for power generation using a Sequential Combustion Cycle (SCC) on a large single shaft engine. This concept allows considerable increase in power density and efficiency by only increasing pressure without raising the maximum hot gas temperature of the cycle. Instead a second combustion after an HP-turbine is used to reheat the gas before the final expansion in an LP-turbine. This concept is applied to the analysis of a high bypass ratio jet engine. In an engine with a single combustor, thrust is a function of bypass ratio and the combination of maximum pressure and temperature in the cycle. The proposed SCC allows increased thrust without pushing technology on materials and cooling. A modern twin spool engine is taken as reference. When total inlet massflow is kept constant, increasing bypass ratio decreases core mass flow. This limits the fuel flow for the HP-spool and hence total energy input to the engine. Introduction of the SCC gives another parameter of freedom to the cycle design. However the twin spool concept is now a disadvantage. The low fuel flow for the HP-spool due to high bypass ratio means there is not enough energy available to build up the necessary pressure for an economical expansion in the LP-turbine after the second combustion. Specific fuel consumption will be unacceptable. It is proposed to apply the SCC concept in a single spool engine with a geared fan. Both turbines can now support the compression. The fan is operated as a constant speed propeller with variable blade pitch. This engine concept allows for a given inlet massflow a substantially higher bypass ratio and hence decreases specific fuel consumption while specific thrust can be kept on a level which will be considerably higher than it would be in todays engines with comparable bypass ratio.

Exergy analysis of a turboprop engine at different flight altitude and speeds using novel consideration

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Ali Dinc ◽  
Yousef Gharbia
Keyword(s):  
Fuel Consumption ◽  
Thermal Efficiency ◽  
Exergy Efficiency ◽  
Specific Fuel Consumption ◽  
Flight Altitude ◽  
Fuel Flow ◽  
Turboprop Engine ◽  
Shaft Power ◽  
Two Parameters ◽  
The Relationship

Abstract In this study, exergy efficiency calculations of a turboprop engine were performed together with main performance parameters such as shaft power, specific fuel consumption, fuel flow, thermal efficiency etc., for a range of flight altitude (0–14 km) and flight speeds (0–0.6 Mach). A novel exergy efficiency formula was derived in terms of specific fuel consumption and it is shown that these two parameters are inversely proportional to each other. Moreover, a novel exergy efficiency and thermal efficiency relation was also derived. The relationship showed that these two parameters are linearly proportional to each other. Exergy efficiency of the turboprop engine was found to be in the range of 23–33%. Thermal efficiency of the turboprop engine was found to be around 25–35%. Exergy efficiency is higher at higher speeds and altitude where the specific fuel consumption is lower. Conversely, exergy efficiency of the engine is lower for lower speeds and altitude where the specific fuel consumption is higher.

An Improvement of Part Load Performance of Diesel Engines Operating at Constant Speed Conditions

1994 ◽  
Vol 208 (1) ◽  
pp. 21-25 ◽  
Author(s):  
A A Abdel-Rahman ◽  
M K Ibrahim ◽  
A A Said
Keyword(s):  
Fuel Consumption ◽  
Diesel Engines ◽  
Petroleum Refining ◽  
Specific Fuel Consumption ◽  
Constant Speed ◽  
Maximum Pressure ◽  
Brake Specific Fuel Consumption ◽  
Part Load ◽  
Generating Sets ◽  
In Series

This paper discusses the possibility of improving the part load performance of diesel electric turbocharged engines operating at constant speed conditions. A sequential turbocharged system is proposed, where the compressors are connected In series. The study focused on two turbocharged diesel–electric generating sets existing at Ameria Petroleum Refining Company in Alexandria, Egypt. The results of the prediction showed that, at part load, both the maximum pressure and temperature were increased, and the brake specific fuel consumption was reduced considerably (by about 10 per cent).

scholarly journals Gears Galore!

2013 ◽  
Vol 135 (04) ◽  
pp. 51-54 ◽  
Author(s):  
Lee S. Langston
Keyword(s):  
Fuel Consumption ◽  
Gas Turbines ◽  
Historical Analysis ◽  
Jet Engines ◽  
Efficient Operation ◽  
Jet Engine ◽  
The Status ◽  
The 1960S ◽  
A Company ◽  
Bypass Ratio

This paper presents a review of gas turbines and Honeywell, a company based in Phoenix, history. The article through the review and historical analysis intends to provide perspective on the status of geared fan engines. The addition of a fan to a jet engine, first proposed by Frank Whittle, one of the inventors of the jet engine, increases thrust and reduces fuel consumption. Pratt & Whitney and Rolls Royce were the first to develop a dual spool engine for more efficient operation over a range of flight conditions. Work started on the geared fan TFE731 at the Garrett AiResearch Phoenix Division in 1968. The TFE731 gearbox resulted in a gear reduction of 1.8:1, to power the fan for a 2.5 bypass ratio, which was very high for the 1960s. Honeywell also has another geared turbofan engine, the ALF502. It was developed by AVCO Lycoming in Stratford, Connecticut, and has a 6000–7000 lbt thrust range. Honeywell’s successful 45-year record of producing geared fan small gas turbines gives promise of a bright future for geared fans on large commercial jet engines, providing lower fuel consumption and less noise.

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.

scholarly journals Effects of Specific Fuel Consumption and Exhaust Emissions of Four Stroke Diesel Engine with CuO/Water Nanofluid as Coolant

2017 ◽  
Vol 64 (1) ◽  
pp. 111-121 ◽  
Author(s):  
S. Senthilraja ◽  
KCK. Vijayakumar ◽  
R. Gangadevi
Keyword(s):  
Diesel Engine ◽  
Fuel Consumption ◽  
Load Condition ◽  
Exhaust Emissions ◽  
Cuo Nanoparticles ◽  
Specific Fuel Consumption ◽  
Gas Temperature ◽  
Step Method ◽  
Series Of Experiments ◽  
Exhaust Gas Temperature

Abstract This article reports the effects of CuO/water based coolant on specific fuel consumption and exhaust emissions of four stroke single cylinder diesel engine. The CuO nanoparticles of 27 nm were used to prepare the nanofluid-based engine coolant. Three different volume concentrations (i.e 0.05%, 0.1%, and 0.2%) of CuO/water nanofluids were prepared by using two-step method. The purpose of this study is to investigate the exhaust emissions (NOx), exhaust gas temperature and specific fuel consumption under different load conditions with CuO/water nanofluid. After a series of experiments, it was observed that the CuO/water nanofluids, even at low volume concentrations, have a significant influence on exhaust emissions. The experimental results revealed that, at full load condition, the specific fuel consumption was reduced by 8.6%, 15.1% and 21.1% for the addition of 0.05%, 0.1% and 0.2% CuO nanoparticles with water, respectively. Also, the emission tests were concluded that 881 ppm, 853 ppm and 833 ppm of NOx emissions were observed at high load with 0.05%, 0.1% and 0.2% volume concentrations of CuO/water nanofluids, respectively.

Analyses and Optimization of a Propulsion Cycle for Unmixed High Bypass Turbofan

2008 ◽  
Author(s):  
Adel Ghenaiet
Keyword(s):  
Fuel Consumption ◽  
Pressure Ratio ◽  
Specific Fuel Consumption ◽  
Design Parameters ◽  
Inlet Temperature ◽  
Turbine Inlet Temperature ◽  
High Pressure Ratio ◽  
Turbine Inlet ◽  
Design Variables ◽  
Bypass Ratio

This paper deals with a parametric study and an optimization for the design variables of a high bypass unmixed turbofan equipping commercial aircrafts. The objective of the first part of this study is to highlight the effects of the principal design parameters (bypass ratio, compression ratios, turbine inlet temperature etc..) on the uninstalled performance, in terms of specific thrust and specific fuel consumption. The second part concerns the optimization, aiming at finding the optimum design parameters concurrently minimizing the specific fuel consumption at cruise, and meeting the thrust requirement at takeoff. The cycle analyzer (on-design and off-design) as coupled to the optimization algorithm MMFD by adopting a random multi-starts search strategy is shown to be stable and converging. The predefined requirements and constraints have dictated utilizing an engine with a high-bypass ratio, high-pressure ratio and a moderate turbine inlet temperature. In general, the obtained results compare fairly well with typical data available for an equivalent ‘reference’ engine. This elaborated methodology is shown to be consistent with the conceptual design requirements and accuracy, because, it does not use components’ characteristics, and operates on simplifying assumptions. This present methodology can be readily adapted for other configurations of aero-engines as well, and easily integrated in a multi-disciplinary design approach.

The Application of Artificial Neural Network in Prediction of the Performance of Spark Ignition Engine Running on Ethanol-Petrol Blends

2017 ◽  
Vol 12 ◽  
pp. 15-31 ◽  
Author(s):  
Olisaemeka C. Nwufo ◽  
Modestus Okwu ◽  
Chidiebere F. Nwaiwu ◽  
Johnson O. Igbokwe ◽  
O. Martin I. Nwafor ◽  
...  
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Fuel Consumption ◽  
Spark Ignition ◽  
Combustion Efficiency ◽  
Spark Ignition Engine ◽  
Specific Fuel Consumption ◽  
Maximum Pressure ◽  
Brake Specific Fuel Consumption ◽  
Artificial Neural

The performance analysis of a single cylinder spark ignition engine fuelled with ethanol – petrol blends were carried out successfully at constant load conditions. E0 (Petrol), E10 (10% Ethanol, 90% Petrol), E20 (20% Ethanol, 80% Petrol) and E30 (30% Ethanol, 70% Petrol) were used as fuel. The Engine speed, mass flow rate, combustion efficiency, maximum pressure developed, brake specific fuel consumption and Exhaust gas temperature values were measured during the experiment. Using the experimental data, a Levenberg Marquardt Artificial Neural Network algorithm and Logistic sigmoid activation transfer function with a 4–10–2 model was developed to predict the brake specific fuel consumption, maximum pressure and combustion efficiency of G200 IMEX spark ignition engine using the recorded engine speed, mass flow rate, biofuels ratio and exhaust gas temperature as input variables. The performance of the Artificial Neural Network was validated by comparing the predicted data with the experimental results. The results showed that the training algorithm of Levenberg Marquardt was sufficient enough in predicting the brake specific fuel consumption, combustion pressure and combustion efficiency of the test engine. Correlation coefficient values of 0.974, 0.996 and 0.995 were obtained for brake specific fuel consumption, combustion efficiency and pressure respectively. These correlation coefficient obtained for the output parameters are very close to one (1) showing good correlation between the Artificial Neural Network predicted results and the experimental data while the Mean Square Errors were found to be very low (0.00018825 @ epoch 10 for brake specific fuel consumption, 1.0023 @ epoch 3 for combustion efficiency and 0.0013284@ epoch 5 for in-cylinder pressure). Therefore, Artificial Neural Network toolbox called up from MATLAB proved to be a useful tool for simulation of engine parameters. Artificial Neural Network model provided accurate analysis of these complex problems and has been found to be very useful for predicting the performance of the spark ignition engine. Thus, this has proved that Artificial Neural Network model could be used for predicting performance values in internal combustion engines, in this way it would be possible to conduct time and cost efficient studies instead of long experimental ones.

Fundamental Differences Between Conventional and Geared Turbofans

2009 ◽  
Author(s):  
Joachim Kurzke
Keyword(s):  
Fuel Consumption ◽  
Real Option ◽  
Pressure Ratio ◽  
Thermodynamic Cycle ◽  
Specific Fuel Consumption ◽  
Thermodynamic Efficiency ◽  
Aircraft Engines ◽  
Direct Drive ◽  
Significant Difference ◽  
Bypass Ratio

The potential for improving the thermodynamic efficiency of aircraft engines is limited because the aerodynamic quality of the turbomachines has already achieved a very high level. While in the past increasing burner exit temperature did contribute to better cycle efficiency, this is no longer the case with today’s temperatures in the range of 1900...2000K. Increasing the cycle pressure ratio above 40 will yield only a small fuel consumption benefit. Therefore the only way to improve the fuel efficiency of aircraft engines significantly is to increase bypass ratio — which yields higher propulsive efficiency. A purely thermodynamic cycle study shows that specific fuel consumption decreases continuously with increasing bypass ratio. However, thermodynamics alone is a too simplistic view of the problem. A conventional direct drive turbofan of bypass ratio 6 looks very different to an engine with bypass ratio 10. Increasing bypass ratio above 10 makes it attractive to design an engine with a gearbox to separate the fan speed from the other low pressure components. Different rules apply for optimizing turbofans of conventional designs and those with a gearbox. This paper describes various criteria to be considered for optimizing the respective engines and their components. For illustrating the main differences between conventional and geared turbofans it is assumed that an existing core of medium pressure ratio with a two stage high pressure turbine is to be used. The design of the engines is done for takeoff rating because this is the mechanically most challenging condition. For each engine the flow annulus is examined and stress calculations for the disks are performed. The result of the integrated aero-thermodynamic and mechanical study allows a comparison of the fundamental differences between conventional and geared turbofans. At the same bypass ratio there will be no significant difference in specific fuel consumption between the alternative designs. The main difference is in the parts count which is much lower for the geared turbofan than for the conventional engine. However, these parts will be mechanically much more challenging than those of a conventional turbofan. If the bypass ratio is increased significantly above 10, then the geared turbofan becomes more and more attractive and the conventional turbofan design is no longer a real option. The maximum practical bypass ratio for ducted fans depends on the nacelle drag and how the installation problems can be solved.

scholarly journals ANALYSIS OF THE EFFECT OF BYPASS RATIO ON PERFORMANCE ENGINE CFM56-5A1 IN CRUISING CONDITIONS

Vortex ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 39
Author(s):  
Opri Surya Yustinoto
Keyword(s):  
Fuel Consumption ◽  
Engine Performance ◽  
Specific Fuel Consumption ◽  
Bypass Ratio ◽  
Consumption Value

The value of engine performance is known to decrease and increase with increasing and decreasing variation of the value of the parameter bypass ratio, so that if the value of these parameters is greater, then the fuel consumption when the aircraft operates will be less and the thrust will decrease. In addition to changing the value of the specific fuel consumption due to the influence of the bypass value, variations in altitude are also very influential where the higher the aircraft, the resulting specific fuel consumption value will be smaller 

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.

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