Parametric Study for Adoption of Variable Cycle Engine Concept for Low Bypass Ratio Turbofan Engine

2019 ◽  
Author(s):  
Kaviya Swaminathan ◽  
Chetan S. Mistry
Keyword(s):  
Fuel Consumption ◽  
Mass Flow ◽  
Parametric Study ◽  
High Efficiency ◽  
Turbofan Engine ◽  
Engine Design ◽  
Flow Through ◽  
Operating Points ◽  
Bypass Ratio ◽  
Multiple Operating Points

Abstract Turbojet and turbofan engine propulsion system are extensively used in aircraft. Turbojets have simple engine design and extensively used for supersonic flights. Turbofan engine has high mass flow rate and efficient for subsonic application. Variable Cycle Engines, unlike the traditional engines, can vary between high thrust mode for supersonic operations and high efficiency mode for subsonic operations hence are potentially attractive for supersonic transport and advanced tactical fighter aircraft. Variable Cycle Engine can be described as the one that operates with two or more cycles, could serve as a possible solution to reconciling the necessary performance at different operating conditions. The aim of the engine is to combine the best traits of turbojet (high specific thrust) and turbofan (low specific fuel consumption, low noise). Traditional engines have fixed mass flow but VCE can alter the mass flow and function as high bypass engine for the subsonic case and low bypass engine at the supersonic case. Different variable cycle engine design philosophies were studied and the engine architecture used in F120 was incorporated into the base design of a low bypass ratio Turbofan Engine. Cycle analysis of VCE was primarily done based on theoretical calculation and parametric study performed with the use of Gasturb software. Two Variable Area Bypass Injectors (VABI) were used to vary the mass flow through the core and the bypass stream. We aspire to achieve enhanced performance at subsonic and supersonic mission segments. Subsonic, supersonic and take off conditions were decided and the base engine was modified to have multiple operating points. The VCE combines two cycles (subsonic, supersonic) in same engine body and it is crucial for the engine components to deliver the required performance at both the design points. The engine design procedure consists of the matching of components like turbine, compressor, exhaust nozzle and the exhaust mixing area. Systematic study of turbine matching for such engine configuration with multiple operating points was carried out to understand the utility of variable geometry in a VCE. For turbine matching, the mass flow through turbine was held constant by adjusting the VABIs and this was repeated for different takeoff conditions to analyses the output in detail. The non dimensional mass flow through the turbine was fixed for both the design points and hence the turbine could be designed to provide high efficiency. The fuel consumption was found to have decreased compared to the baseline condition which in turn leads to low SFC and higher endurance.

scholarly journals Turbogenerator Steam Turbine Variation in Developed Power: Analysis of Exergy Efficiency and Exergy Destruction Change

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Vedran Mrzljak ◽  
Tomislav Senčić ◽  
Božica Žarković
Keyword(s):  
Steam Turbine ◽  
Mass Flow ◽  
Power Analysis ◽  
Exergy Efficiency ◽  
Operating Point ◽  
Exergy Destruction ◽  
Flow Through ◽  
Power Measurements ◽  
Operating Points ◽  
Insight Into

Developed power variation of turbogenerator (TG) steam turbine, which operates at the conventional LNG carrier, allows insight into the change in turbine exergy efficiency and exergy destruction during the increase in turbine power. Measurements of required operating parameters were performed in eight different TG steam turbine operating points during exploitation. Turbine exergy efficiency increases from turbine power of 500 kW up to 2700 kW, and maximum exergy efficiency was obtained at 70.13% of maximum turbine developed power (at 2700 kW) in each operating point. From turbine developed power of 2700 kW until the maximum power of 3850 kW, exergy efficiency decreases. Obtained change in TG turbine exergy efficiency is caused by an uneven intensity of increase in turbine developed power and steam mass flow through the turbine. TG steam turbine exergy destruction change is directly proportional to turbine load and to steam mass flow through the turbine—higher steam mass flow results in a higher turbine load which leads to the higher exergy destruction and vice versa. The higher share of turbine developed power and the lower share of turbine exergy destruction in the TG turbine exergy power inlet lead to higher turbine exergy efficiencies. At each observed operating point, turbine exergy efficiency in exploitation is lower when compared to the maximum obtained one for 8.39% to 12.03%.

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.

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.

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.

Off-Design Performance of an Interstage Turbine Burner Turbofan Engine

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Feijia Yin ◽  
Arvind G. Rao
Keyword(s):  
Fuel Efficiency ◽  
Cycle Performance ◽  
Inlet Temperature ◽  
Engine Operation ◽  
Turbofan Engine ◽  
Design Performance ◽  
Low Pressure Turbine ◽  
Performance Requirements ◽  
Engine Design ◽  
Operating Points

This paper focuses on the off-design performance of a turbofan engine with an interstage turbine burner (ITB). The ITB is an additional combustion chamber located between the high-pressure turbine (HPT) and the low-pressure turbine (LPT). The incorporation of ITB in an engine can provide several advantages, especially due to the reduction in the HPT inlet temperature and the associated NOx emission reduction. The objective is to evaluate the effects of the ITB on the off-design performance of a turbofan engine. The baseline engine is a contemporary classical turbofan. The effects of the ITB are evaluated on two aspects: first, the influences of an ITB on the engine cycle performance; second, the influences of an ITB on the component characteristics. The dual combustors of an ITB engine provide an extra degree-of-freedom for the engine operation. The analysis shows that a conventional engine has to be oversized to satisfy off-design performance requirement, like the flat rating temperature. However, the application of an ITB eases the restrictions imposed by the off-design performance requirements on the engine design, implying that the off-design performance of an ITB engine can be satisfied without sacrificing the fuel efficiency. Eventually, the performance of the ITB engine exhibits superior characteristics over the baseline engine at the studied operating points over a flight mission.

scholarly journals Parameterization of a Conventional and Regenerated UHB Turbofan

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Fábio Oliveira ◽  
Francisco Brójo
Keyword(s):  
Fuel Consumption ◽  
First Generation ◽  
Specific Fuel Consumption ◽  
Aircraft Engines ◽  
Turbofan Engine ◽  
Commercial Aviation ◽  
Technological Developments ◽  
Specific Thrust ◽  
Aero Engines ◽  
Bypass Ratio

AbstractThe attempt to improve aircraft engines efficiency resulted in the evolution from turbojets to the first generation low bypass ratio turbofans. Today, high bypass ratio turbofans are the most traditional type of engine in commercial aviation. Following many years of technological developments and improvements, this type of engine has proved to be the most reliable facing the commercial aviation requirements. In search of more efficiency, the engine manufacturers tend to increase the bypass ratio leading to ultra-high bypass ratio (UHB) engines. Increased bypass ratio has clear benefits in terms of propulsion system like reducing the specific fuel consumption. This study is aimed at a parametric analysis of a UHB turbofan engine focused on short haul flights. Two cycle configurations (conventional and regenerated) were studied, and estimated values of their specific fuel consumption (TSFC) and specific thrust (Fs) were determined. Results demonstrate that the regenerated cycle may contribute towards a more economic and friendly aero engines in a higher range of bypass ratio.

Performance Evaluation for the Application of Variable Turbine-Cooling-Bleeds in Civil Turbofans

2007 ◽  
Author(s):  
Vasileios E. Kyritsis ◽  
Pericles Pilidis
Keyword(s):  
Mass Flow ◽  
Turbine Rotor ◽  
Preliminary Evaluation ◽  
Critical Temperatures ◽  
Turbine Cooling ◽  
Cooling Flow ◽  
Fuel Burn ◽  
Flow Through ◽  
Mass Flows ◽  
Operating Points

Frequently, the mechanical integrity of gas turbine components is designed for a hot day, sea level take-off, where the maximum values are encountered for critical temperatures, such as the ones at the compressor and combustor outlet and the turbine rotor inlet stations. Turbine cooling flow rates are then defined taking into consideration maximum allowable metal temperatures, stresses, component life expectancy and heat transfer technology. Remaining unchanged as a percent of the core engine mass flow through the rest of the flight envelope, excessive cooling mass flows are actually being used during the cruise and the descent segment, since these operating points are characterized by significantly reduced temperatures. The main objective of the current work is the preliminary evaluation of the performance benefits, which can be achieved during a long range civil flight when decreasing the cooling bleed fraction during cruise. This is considered an essential step before any study concerning the consequences upon lifing is conducted. A conventional engine is optimized to meet the respective flight requirements, operating under constant cooling fraction throughout the mission. Reduction in cooling mass flow is applied, changing in such a way its off-design performance. Changes in typical engine parameters are identified and are graphically presented versus bleed flow reduction. Moreover, making use of a model providing for the drag polar of an airframe, while taking into account of the continuous weight reduction due to fuel burn, the variation of fuel consumption during cruise is also calculated. Fuel benefits are identified; a 40% reduction of the cooling fraction results in cruise fuel dropping by 0.75%. This can be justified on the basis of decreasing the cooling of the mainstream and increasing the mass flow, which is expanded through the turbine stages upstream. Although a metal temperature increase is also expected, it is accompanied by a Combustor Outlet and Turbine Entry temperature reduction.

scholarly journals Phase Distribution in the Tip Clearance of a Multiphase Pump at Multiple Operating Points and Its Effect on the Pressure Fluctuation Intensity

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 556
Author(s):  
Guangtai Shi ◽  
Zongku Liu ◽  
Xiaobing Liu ◽  
Yexiang Xiao ◽  
Xuelin Tang
Keyword(s):  
Phase Velocity ◽  
Pressure Fluctuation ◽  
Phase Distribution ◽  
Tip Clearance ◽  
Tip Leakage Flow ◽  
Two Phase ◽  
Multiphase Pump ◽  
Fluctuation Intensity ◽  
Operating Points ◽  
Multiple Operating Points

Tip clearance has a great effect on the flow and pressure fluctuation characteristics in a multiphase pump, especially at multiple operating points. The phase distribution and pressure fluctuation in tip clearance in a multiphase pump are revealed using the CFD (computational fluid dynamics) technology and high-speed photography methods. In this paper, the phase distribution, the gas-liquid two-phase velocity slip, and the pressure fluctuation intensity are comprehensively analyzed. Results show with the increase of the tip clearance, the multiphase pump pressurization performance is obviously deteriorated. In the meantime, the gas accumulation mainly occurs at the hub, the blade suction side (SS), and the tip clearance, and the maximum gas-liquid two-phase velocity difference is near the impeller streamwise of 0.4. In addition, the tip clearance improves the gas-liquid two-phase distribution in the pump, that is, the larger the tip clearance is, the more uniform the gas-liquid distribution becomes. Furthermore, the gas leads to the maximum pressure fluctuation intensity in the tip clearance which is closer to the tip leakage flow (TLF) outlet, and has a greater effect on the degree of flow separation in the tip clearance.

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