First and Second Law Analysis of Intercooled Turbofan Engine

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Xin Zhao ◽  
Oskar Thulin ◽  
Tomas Grönstedt
Keyword(s):  
High Pressure ◽  
Conceptual Design ◽  
Exergy Analysis ◽  
Second Law ◽  
Turbofan Engine ◽  
Blade Height ◽  
Turbofan Engines ◽  
Fuel Burn ◽  
Aero Engine ◽  
Last Stage

Although the benefits of intercooling for aero-engine applications have been realized and discussed in many publications, quantitative details are still relatively limited. In order to strengthen the understanding of aero-engine intercooling, detailed performance data on optimized intercooled (IC) turbofan engines are provided. Analysis is conducted using an exergy breakdown, i.e., quantifying the losses into a common currency by applying a combined use of the first and second law of thermodynamics. Optimal IC geared turbofan engines for a long range mission are established with computational fluid dynamics (CFD) based two-pass cross flow tubular intercooler correlations. By means of a separate variable nozzle, the amount of intercooler coolant air can be optimized to different flight conditions. Exergy analysis is used to assess how irreversibility is varying over the flight mission, allowing for a more clear explanation and interpretation of the benefits. The optimal IC geared turbofan engine provides a 4.5% fuel burn benefit over a non-IC geared reference engine. The optimum is constrained by the last stage compressor blade height. To further explore the potential of intercooling the constraint limiting the axial compressor last stage blade height is relaxed by introducing an axial radial high pressure compressor (HPC). The axial–radial high pressure ratio (PR) configuration allows for an ultrahigh overall PR (OPR). With an optimal top-of-climb (TOC) OPR of 140, the configuration provides a 5.3% fuel burn benefit over the geared reference engine. The irreversibilities of the intercooler are broken down into its components to analyze the difference between the ultrahigh OPR axial–radial configuration and the purely axial configuration. An intercooler conceptual design method is used to predict pressure loss heat transfer and weight for the different OPRs. Exergy analysis combined with results from the intercooler and engine conceptual design are used to support the conclusion that the optimal PR split exponent stays relatively independent of the overall engine PR.

First and Second Law Analysis of Intercooled Turbofan Engine

2015 ◽  
Author(s):  
Xin Zhao ◽  
Oskar Thulin ◽  
Tomas Grönstedt
Keyword(s):  
High Pressure ◽  
Exergy Analysis ◽  
Pressure Ratio ◽  
Second Law ◽  
Turbofan Engine ◽  
Blade Height ◽  
Turbofan Engines ◽  
Fuel Burn ◽  
Aero Engine ◽  
Last Stage

Although the benefits of intercooling for aero engine applications have been realized and discussed in many publications, quantitative details are still relatively limited. In order to strengthen the understanding of aero engine intercooling, detailed performance data on optimized intercooled turbofan engines are provided. Analysis is conducted using an exergy breakdown, i.e. quantifying the losses into a common currency by applying a combined use of the first and second law of thermodynamics. Optimal intercooled geared turbofan engines for a long range mission are established with CFD based two-pass cross flow tubular intercooler correlations. By means of a separate variable nozzle, the amount of intercooler coolant air can be optimized to different flight conditions. Exergy analysis is used to assess how irreversibility is varying over the flight mission, allowing for a more clear explanation and interpretation of the benefits. The optimal intercooled geared turbofan engine provides a 4.5% fuel burn benefit over a non-intercooled geared reference engine. The optimum is constrained by the last stage compressor blade height. To further explore the potential of intercooling the constraint limiting the axial compressor last stage blade height is relaxed by introducing an axial radial high pressure compressor. The axial-radial high pressure ratio configuration allows for an ultra-high overall pressure ratio. With an optimal top-of-climb overall pressure ratio of 140, the configuration provides a 5.3% fuel burn benefit over the geared reference engine. The irreversibilities of the intercooler are broken down into its components to analyze the difference between the ultra-high overall pressure ratio axial-radial configuration and the purely axial configuration. An intercooler conceptual design method is used to predict pressure loss heat transfer and weight for the different overall pressure ratios. Exergy analysis combined with results from the intercooler and engine conceptual design are used to support the conclusion that the optimal pressure ratio split exponent stays relatively independent of the overall engine pressure ratio.

Feasibility Study of a Radical Vane-Integrated Heat Exchanger for Turbofan Engine Applications

2020 ◽  
Author(s):  
Isak Jonsson ◽  
Carlos Xisto ◽  
Hamidreza Abedi ◽  
Tomas Grönstedt ◽  
Marcus Lejon
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Conceptual Design ◽  
Feasibility Study ◽  
Compact Heat Exchanger ◽  
Turbofan Engine ◽  
Turbine Engine ◽  
Compression System ◽  
Last Stage ◽  
Pressure Compressor

Abstract In the present study, a compact heat exchanger for cryogenically fueled gas turbine engine applications is introduced. The proposed concept can be integrated into one or various vanes that comprise the compression system and uses the existing vane surface to reject core heat to the cryogenic fuel. The requirements for the heat exchanger are defined for a large geared-turbofan engine operating on liquid hydrogen. The resulting preliminary conceptual design is integrated into a modified interconnecting duct and connected to the last stage of a publicly available low-pressure compressor geometry. The feasibility of different designs is investigated numerically, providing a first insight on the parameters that govern the design of such a component.

scholarly journals Mathematical model of turbofan engine weight estimation taking into account the engine configuration and size

2021 ◽  
Vol 20 (1) ◽  
pp. 5-13
Author(s):  
S. V. Avdeev
Keyword(s):  
Gas Turbine ◽  
Conceptual Design ◽  
Air Flow ◽  
Turbine Engines ◽  
Average Error ◽  
Gas Turbine Engines ◽  
Turbofan Engine ◽  
Turbofan Engines ◽  
Structural Layout ◽  
Mixing Chamber

The paper presents a new correlation-regression model of estimating the turbofan engine weight considering the effect of the engines design schemes and dimensions. The purpose of this study was to improve the efficiency of the conceptual design process for aircraft gas turbine engines. Information on 183 modern turbofan engines was gathered using the available sources: publications, official websites, reference books etc. The statistic information included the values of the total engine air flow, the total turbine inlet gas temperature, the overall pressure ratio and the bypass ratio, as well as information on the structural layout of each engine. The engines and the related statistics were classified according to their structural layout and size. Size classification was based on the value of the compressor outlet air flow through the gas generator given by the parameters behind the compressor. Depending on the value of this criterion, the engines were divided into three groups: small-sized, medium-sized gas turbine engines, and large gas turbine engines. In terms of the structural layout, all engines were divided into three groups: turbofan engines without a mixing chamber, engines with a mixing chamber and afterburning turbofan engines. Statistical factors of the improved weight model were found for the respective groups of engines, considering their design and size. The coefficients of the developed model were determined by minimizing the standard deviations. Regression analysis was carried out to assess the quality of the developed model. The relative average error of approximation of the developed model was 8%, the correlation coefficient was 0,99, and the standard deviation was 10,2%. The model was found to be relevant and reliable according to Fisher's test. The obtained model can be used to assess the engine weight at the stage of conceptual design and for its optimization as part of an aircraft.

scholarly journals Design Considerations of Low Bypass Ratio Mixed Flow Turbofan Engines with Large Power Extraction

Fluids ◽  
2022 ◽  
Vol 7 (1) ◽  
pp. 21
Author(s):  
Daniel Rosell ◽  
Tomas Grönstedt
Keyword(s):  
High Pressure ◽  
Inlet Temperature ◽  
Mixed Flow ◽  
Turbine Inlet Temperature ◽  
Fighter Aircraft ◽  
Turbofan Engine ◽  
Large Power ◽  
Power Extraction ◽  
Turbofan Engines ◽  
Bypass Ratio

The possibility of extracting large amounts of electrical power from turbofan engines is becoming increasingly desirable from an aircraft perspective. The power consumption of a future fighter aircraft is expected to be much higher than today’s fighter aircraft. Previous work in this area has concentrated on the study of power extraction for high bypass ratio engines. This motivates a thorough investigation of the potential and limitations with regards to performance of a low bypass ratio mixed flow turbofan engine. A low bypass ratio mixed flow turbofan engine was modeled, and key parts of a fighter mission were simulated. The investigation shows how power extraction from the high-pressure turbine affects performance of a military engine in different parts of a mission within the flight envelope. An important conclusion from the analysis is that large amounts of power can be extracted from the turbofan engine at high power settings without causing too much penalty on thrust and specific fuel consumption, if specific operating conditions are fulfilled. If the engine is operating (i) at, or near its maximum overall pressure ratio but (ii) further away from its maximum turbine inlet temperature limit, the detrimental effect of power extraction on engine thrust and thrust specific fuel consumption will be limited. On the other hand, if the engine is already operating at its maximum turbine inlet temperature, power extraction from the high-pressure shaft will result in a considerable thrust reduction. The results presented will support the analysis and interpretation of fighter mission optimization and cycle design for future fighter engines aimed for large power extraction. The results are also important with regards to aircraft design, or more specifically, in deciding on the best energy source for power consumers of the aircraft.

scholarly journals Assessment of CO2 and NOx Emissions in Intercooled Pulsed Detonation Turbofan Engines

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Carlos Xisto ◽  
Olivier Petit ◽  
Tomas Grönstedt ◽  
Anders Lundbladh
Keyword(s):  
Gas Turbine ◽  
Equivalence Ratio ◽  
Nox Emissions ◽  
Simulation Tool ◽  
Turbofan Engines ◽  
Fuel Burn ◽  
Pulsed Detonation ◽  
Detonation Combustion ◽  
Aero Engine ◽  
Computational Fluid Dynamics Cfd

In the present paper, the synergistic combination of intercooling with pulsed detonation combustion is analyzed concerning its contribution to NOx and CO2 emissions. CO2 is directly proportional to fuel burn and can, therefore, be reduced by improving specific fuel consumption (SFC) and reducing engine weight and nacelle drag. A model predicting NOx generation per unit of fuel for pulsed detonation combustors (PDCs), operating with jet-A fuel, is developed and integrated within Chalmers University's gas turbine simulation tool GESTPAN. The model is constructed using computational fluid dynamics (CFD) data obtained for different combustor inlet pressure, temperature, and equivalence ratio levels. The NOx model supports the quantification of the trade-off between CO2 and NOx emissions in a 2050 geared turbofan architecture incorporating intercooling and pulsed detonation combustion and operating at pressures and temperatures of interest in gas turbine technology for aero-engine civil applications.

Advanced Exergy Analysis of a Turbofan Engine (TFE): Splitting Exergy Destruction into Unavoidable/Avoidable and Endogenous/Exogenous

2017 ◽  
Vol 0 (0) ◽  
Author(s):  
Ozgur Balli
Keyword(s):  
High Pressure ◽  
Exergy Analysis ◽  
Low Pressure ◽  
Operating Conditions ◽  
Actual Condition ◽  
Exergy Destruction ◽  
Turbofan Engine ◽  
High Pressure Compressor ◽  
Engine Components ◽  
Pressure Compressor

AbstractA conventional and advanced exergy analysis of a turbofan engine is presented in this paper. In this framework, the main exergy parameters of the engine components are introduced while the exergy destruction rates within the engine components are split into endogenous/exogenous and avoidable/unavoidable parts. Also, the mutual interdependencies among the components of the engine and realistic improvement potentials depending on operating conditions are acquired through the analysis. As a result of the study, the exergy efficiency values of the engine are determined to be 25.7 % for actual condition, 27.55 % for unavoidable condition and 30.54 % for theoretical contion, repectively. The system has low improvement potential because the unavoidable exergy destruction rate is 90 %. The relationships between the components are relatively weak since the endogenous exergy destruction is 73 %. Finally, it may be concluded that the low pressure compressor, the high pressure compressor, the fan, the low pressure compressor, the high pressure compressor and the combustion chamber of the engine should be focused on according to the results obtained.

On the Optimization of a Geared Fan Intercooled Core Engine Design

2014 ◽  
Vol 137 (4) ◽  
Author(s):  
Konstantinos G. Kyprianidis ◽  
Andrew M. Rolt
Keyword(s):  
Fuel Consumption ◽  
Design Space ◽  
Pressure Ratio ◽  
System Level ◽  
Design Parameters ◽  
Customer Requirements ◽  
Blade Height ◽  
Fuel Burn ◽  
Engine Design ◽  
Last Stage

Reduction of CO2 emissions is strongly linked with the improvement of engine specific fuel consumption (SFC), as well as the reduction of engine nacelle drag and weight. One alternative design approach to improving SFC is to consider a geared fan combined with an increased overall pressure ratio (OPR) intercooled core performance cycle. Thermal benefits from intercooling have been well documented in the literature. Nevertheless, there is little information available in the public domain with respect to design space exploration of such an engine concept when combined with a geared fan. The present work uses a multidisciplinary conceptual design tool to further analyze the option of an intercooled core geared fan aero engine for long haul applications with a 2020 entry into service technology level assumption. The proposed design methodology is capable, with the utilized tool, of exploring the interaction of design criteria and providing critical design insight at engine–aircraft system level. Previous work by the authors focused on understanding the design space for this particular configuration with minimum SFC, engine weight, and mission fuel in mind. This was achieved by means of a parametric analysis, varying several engine design parameters—but only one at a time. The present work attempts to identify “globally” fuel burn optimal values for a set of engine design parameters by varying them all simultaneously. This permits the nonlinear interactions between the parameters to be accounted for. Special attention has been given to the fuel burn impact of the reduced high pressure compressor (HPC) efficiency levels associated with low last stage blade heights. Three fuel optimal designs are considered, based on different assumptions. The results indicate that it is preferable to trade OPR and pressure ratio split exponent, rather than specific thrust, as means of increasing blade height and hence reducing the associated fuel consumption penalties. It is interesting to note that even when considering the effect of HPC last stage blade height on efficiency there is still an equivalently good design at a reduced OPR. This provides evidence that the overall economic optimum could be for a lower OPR cycle. Customer requirements such as take-off distance and time to height play a very important role in determining a fuel optimal engine design. Tougher customer requirements result in bigger and heavier engines that burn more fuel. Higher OPR intercooled engine cycles clearly become more attractive in aircraft applications that require larger engine sizes.

An Intercooled Recuperative Aero Engine for Regional Jets

2014 ◽  
Author(s):  
Maximilian Kormann ◽  
Reinhold Schaber
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Thermodynamic Efficiency ◽  
Parameter Study ◽  
Nox Emissions ◽  
Turbofan Engines ◽  
Fuel Burn ◽  
Aero Engine ◽  
Aero Engines ◽  
Regional Jets

Flying requires a high power density in the propulsion system. Currently only turbofan engines can provide the required power at a low system mass. To counter a potential negative impact of aircraft emissions on global climate, the agreement Flightpath 50, created by European research establishments and industries, has set the target to reduce overall CO2 emissions from the year 2000 to 2050 by 75 %. In contrast, the air traffic volume has been growing constantly since the 1980s and will be growing further. Hence the fuel burn of aero engines has to be reduced to reach the Flightpath 50 target. High-end component technology has nearly exhausted full potential in the improvement of conventional turbofan engines. Further significant progress can only be achieved by new engine concepts. The geared turbofan has proven the feasibility of this approach. The introduction of a gear allows the IPC and LPT to run at more suitable speeds with the consequence of a lower stage count compared to conventional turbofans. According to Pratt&Whitney this will reduce the fuel burn by ”15–16% versus today’s best engines” [1]. As a next step towards Flightpath 50 MTU Aero Engines AG envisioned the Intercooled Recuperative Aero Engine (IRA) for long-haul application. This concept increases the thermodynamic efficiency of the core engine by utilizing two heat exchangers: an intercooler reduces the work which is necessary for the compression. A recuperator transfers heat of the exhaust gas to the compressed gas entering the burner. In long-haul aircraft the increased engine mass due to the heat exchangers has a lower influence on the fuel burn. To broaden the research, this paper investigates the application of the IRA for regional jets. An extensive predesign parameter study was performed to find the optimal IRA configuration for regional jets. Not only has fuel consumption been taken into consideration, additionally the influence of the increased weight of the IRA has been included. In optimum, the fuel burn on a regional mission according to this study could be reduced in the order of 1–2%. However, the overall pressure ratio is much lower compared to modern turbofan engines, which leads to relatively low NOx emissions. It allows the introduction of Lean Premixed Prevaporized (LPP) burner technology, promising an additional significant reduction in NOx emissions compared to modern turbofan engines. Compared to a longhaul application the heat exchangers are not a scaled version but the result of a cycle optimization considering the available space. The paper also gives an outlook for an innovative three dimensional heat exchanger. The novel heat exchanger arrangement promises a better integration into the annulus at turbine exit and less aerodynamical pressure losses due to 3D-effects.

On the Optimisation of a Geared Fan Intercooled Core Engine Design

2014 ◽  
Author(s):  
Konstantinos G. Kyprianidis ◽  
Andrew M. Rolt
Keyword(s):  
Fuel Consumption ◽  
Design Space ◽  
Pressure Ratio ◽  
Specific Fuel Consumption ◽  
Design Parameters ◽  
Customer Requirements ◽  
Blade Height ◽  
Fuel Burn ◽  
Engine Design ◽  
Last Stage

Reduction of CO2 emissions is strongly linked with the improvement of engine specific fuel consumption, as well as the reduction of engine nacelle drag and weight. One alternative design approach to improving specific fuel consumption is to consider a geared fan combined with an increased overall pressure ratio intercooled core performance cycle. Thermal benefits from intercooling have been well documented in the literature. Nevertheless, there is little information available in the public domain with respect to design space exploration of such an engine concept when combined with a geared fan. The present work uses a multidisciplinary conceptual design tool to further analyse the option of an intercooled core geared fan aero engine for long haul applications with a 2020 entry into service technology level assumption. The proposed design methodology is capable, with the utilised tool, of exploring the interaction of design criteria and providing critical design insight at engine-aircraft system level. Previous work by the authors focused on understanding the design space for this particular configuration with minimum specific fuel consumption, engine weight and mission fuel in mind. This was achieved by means of a parametric analysis, varying several engine design parameters — but only one at a time. The present work attempts to identify “globally” fuel burn optimal values for a set of engine design parameters by varying them all simultaneously. This permits the non-linear interactions between the parameters to be accounted. Special attention has been given to the fuel burn impact of the reduced HPC efficiency levels associated with low last stage blade heights. Three fuel optimal designs are considered, based on different assumptions. The results indicate that it is preferable to trade overall pressure ratio and pressure ratio split exponent, rather than specific thrust, as means of increasing blade height and hence reducing the associated fuel consumption penalties. It is interesting to note that even when considering the effect of HPC last stage blade height on efficiency there is still an equivalently good design at a reduced overall pressure ratio. This provides evidence that the overall economic optimum could be for a lower overall pressure ratio cycle. Customer requirements such as take-off distance and time to height play a very important role in determining a fuel optimal engine design. Tougher customer requirements result in bigger and heavier engines that burn more fuel. Higher overall pressure ratio intercooled engine cycles clearly become more attractive in aircraft applications that require larger engine sizes.

scholarly journals Assessment of CO2 and NOx Emissions in Intercooled Pulsed Detonation Turbofan Engines

2018 ◽  
Author(s):  
Carlos Xisto ◽  
Olivier Petit ◽  
Tomas Grönstedt ◽  
Anders Lundbladh
Keyword(s):  
Gas Turbine ◽  
Equivalence Ratio ◽  
Nox Emissions ◽  
Simulation Tool ◽  
Trade Off ◽  
Turbofan Engines ◽  
Fuel Burn ◽  
Pulsed Detonation ◽  
Detonation Combustion ◽  
Aero Engine

In the present paper, the synergistic combination of inter-cooling with pulsed detonation combustion is analyzed concerning its contribution to NOx and CO2 emissions. CO2 is directly proportional to fuel burn and can, therefore, be reduced by improving specific fuel consumption and reducing engine weight and nacelle drag. A model predicting NOx generation per unit of fuel for pulsed detonation combustors, operating with jet-A fuel, is developed and integrated within Chalmers University’s gas turbine simulation tool GESTPAN. The model is constructed using CFD data obtained for different combustor inlet pressure, temperature and equivalence ratio levels. The NOx model supports the quantification of the trade-off between CO2 and NOx emissions in a 2050 geared turbofan architecture incorporating intercooling and pulsed detonation combustion and operating at pressures and temperatures of interest in gas turbine technology for aero-engine civil applications.

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