A high bypass ratio turbofan engine capable of powering the Boeing 757 was considered for thrust and drag analysis. A quasi-2D engine model applying the fundamental thermodynamics conservation equations and practical constraints determined engine performance and provided cross-sectional areas in the low-pressure system. Coupled with suggestions on boat-tail angle and curvature from literature, a representative bypass duct and primary exhaust nozzle was created. 3D steady-RANS simulations using Fluent® 18 were performed on a 1/8th axisymmetric section of the geometry. A modified 3D fan zone model forcing radial equilibrium was used to model the fan and bypass stator. Takeoff speed and cruise operating conditions were modeled and simulated to identify changes in thrust composition and intake sensitivity. Comparison between net thrust predictions by the engine model and measured in CFD were within grid uncertainty and model sensitivity at cruise. Trends observed in a published database were satisfied and calculations coincided with GasTurb™ 8.0. Verification of thrust in this manner gave confidence to the aerodynamic performance prediction of this modest CFD. Obtaining a baseline bypass design would allow rapid testing of aftermarket components and integration techniques in a realistic flow-field without reliance on proprietary engine data.
{"title":"Estimating the Drag Developed by a High Bypass Ratio Turbofan Engine","authors":"M. Zawislak, D. Cerantola, A. M. Birk","doi":"10.1115/GT2018-75204","DOIUrl":"https://doi.org/10.1115/GT2018-75204","url":null,"abstract":"A high bypass ratio turbofan engine capable of powering the Boeing 757 was considered for thrust and drag analysis. A quasi-2D engine model applying the fundamental thermodynamics conservation equations and practical constraints determined engine performance and provided cross-sectional areas in the low-pressure system. Coupled with suggestions on boat-tail angle and curvature from literature, a representative bypass duct and primary exhaust nozzle was created. 3D steady-RANS simulations using Fluent® 18 were performed on a 1/8th axisymmetric section of the geometry. A modified 3D fan zone model forcing radial equilibrium was used to model the fan and bypass stator. Takeoff speed and cruise operating conditions were modeled and simulated to identify changes in thrust composition and intake sensitivity. Comparison between net thrust predictions by the engine model and measured in CFD were within grid uncertainty and model sensitivity at cruise. Trends observed in a published database were satisfied and calculations coincided with GasTurb™ 8.0. Verification of thrust in this manner gave confidence to the aerodynamic performance prediction of this modest CFD. Obtaining a baseline bypass design would allow rapid testing of aftermarket components and integration techniques in a realistic flow-field without reliance on proprietary engine data.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"113 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117295731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Considering the increasing development of naval destroyers and the obvious advantages of marine gas turbine, this paper designs a novel COGAG (Combined Gas-turbine And Gas-turbine) propulsion system which mainly consists of four GT25 marine gas turbines and one CCG (Cross Connection Gears) for the large destroyer. Firstly, the overall configuration and key devices of COGAG propulsion system are introduced briefly. Then, the typical operating patterns of COGAG propulsion system under different condition are discussed in detail. Finally, many experimental information are further presented. All the results show that the developed COGAG propulsion system not only has higher flexibility and reliability, but also can effectively improve the fuel economy of marine ships.
{"title":"A Novel COGAG Propulsion System for Marine Ships","authors":"Zhenzhong Xu, Xueyou Wen, Ningbo Zhao","doi":"10.1115/GT2018-75908","DOIUrl":"https://doi.org/10.1115/GT2018-75908","url":null,"abstract":"Considering the increasing development of naval destroyers and the obvious advantages of marine gas turbine, this paper designs a novel COGAG (Combined Gas-turbine And Gas-turbine) propulsion system which mainly consists of four GT25 marine gas turbines and one CCG (Cross Connection Gears) for the large destroyer. Firstly, the overall configuration and key devices of COGAG propulsion system are introduced briefly. Then, the typical operating patterns of COGAG propulsion system under different condition are discussed in detail. Finally, many experimental information are further presented. All the results show that the developed COGAG propulsion system not only has higher flexibility and reliability, but also can effectively improve the fuel economy of marine ships.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128406668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bearing chamber of a gas turbine engine is generally sealed by pressurized air, separating lubricant from the other zones of the engine. Heat transfer from the wall to air/oil mixture is a challenging engineering problem; predicting heat transfer rate from bearing chamber to oil is important to avoid oil coking and oil fires under high rotational speeds, pressure levels and turbine inlet temperatures. In this study, the inner wall temperature of bearing chamber which is located at the center of front engine structure was investigated numerically. The numerical study involved mainly two thermal modelling methods having two different empirical correlations was performed with finite element solver in order to calculate heat transfer on the wall. First method was based on rotational Reynolds number and Prantl number, in addition to these numbers second one, which is suggested in the literature, is based on oil related and sealing air related Reynolds number, mixture temperature and mixture mass flow. Second approach considers existence of a mixing of gaseous and liquid flow in the core flow unlike first modelling approach. The thermal model was solved by finite element solver and numerical model, assumptions were described with thermal boundary conditions. On the other hand, wall and air thermocouple readings were taken through engine test from the bearing chamber for real engine operating conditions having mainly idle, cruise and maximum power. DN number ranges from 712564 to 2742404, sealing air flow ranges from 46 to 78 g/s and oil flow ranges 22 to 40 g/s for these conditions. The calculated heat transfer coefficients were presented and discussed. The wall temperature predictions of the thermal models, and test measurements were compared. The comparison revealed that analysis results obtained with both correlations were in reasonable agreement with the test. In overall, the second approach predicted metal temperature slightly better at the front support and inner manifold wall, while first approach predicted much better at the rear support wall.
{"title":"Numerical Investigation on Bearing Chamber Wall Heat Transfer","authors":"V. Tatar, A. Pişkin","doi":"10.1115/GT2018-75721","DOIUrl":"https://doi.org/10.1115/GT2018-75721","url":null,"abstract":"Bearing chamber of a gas turbine engine is generally sealed by pressurized air, separating lubricant from the other zones of the engine. Heat transfer from the wall to air/oil mixture is a challenging engineering problem; predicting heat transfer rate from bearing chamber to oil is important to avoid oil coking and oil fires under high rotational speeds, pressure levels and turbine inlet temperatures. In this study, the inner wall temperature of bearing chamber which is located at the center of front engine structure was investigated numerically. The numerical study involved mainly two thermal modelling methods having two different empirical correlations was performed with finite element solver in order to calculate heat transfer on the wall. First method was based on rotational Reynolds number and Prantl number, in addition to these numbers second one, which is suggested in the literature, is based on oil related and sealing air related Reynolds number, mixture temperature and mixture mass flow. Second approach considers existence of a mixing of gaseous and liquid flow in the core flow unlike first modelling approach. The thermal model was solved by finite element solver and numerical model, assumptions were described with thermal boundary conditions. On the other hand, wall and air thermocouple readings were taken through engine test from the bearing chamber for real engine operating conditions having mainly idle, cruise and maximum power. DN number ranges from 712564 to 2742404, sealing air flow ranges from 46 to 78 g/s and oil flow ranges 22 to 40 g/s for these conditions. The calculated heat transfer coefficients were presented and discussed. The wall temperature predictions of the thermal models, and test measurements were compared. The comparison revealed that analysis results obtained with both correlations were in reasonable agreement with the test. In overall, the second approach predicted metal temperature slightly better at the front support and inner manifold wall, while first approach predicted much better at the rear support wall.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"42 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114076833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Asad Asghar, Stephen A. Pym, W. Allan, M. Laviolette, R. Stowe
High subsonic aircraft with fuselage-embedded engines often employ inlet ducts with multiple bends in order to induct ambient air into the propulsion system while also diffusing it to engine-acceptable Mach numbers. Engine performance, stability margin, and safety of the integrated aircraft-engine system can be negatively affected by separated, swirling and distorted flow that often characterizes S-ducts. This paper reports the investigation of a flow control strategy aimed at the improvement of the aerodynamic performance of S-duct diffusers. Passive pressure equalization was employed to reduce the size and intensity of the separated flow downstream of curved duct sections, utilizing naturally occurring pressure differences. Characteristic secondary flows promote instability and contribute to flow separation and losses in the inner radius region of a duct bend. In the present scheme, boundary layer flow upstream of the separation point on the inner radius of the first bend is energized by re-injecting higher momentum air, drawn from the higher pressure region at the outer radius of the same bend. The flow control effectiveness of this passive pressure equalization was evaluated by test-rig measurements of the flow in an S-duct at an inlet Mach number of 0.80. Static surface pressure was measured along the length of the S-duct and the total pressure was measured at the aerodynamic interface plane using a pressure rake with five high performance pressure transducers. It was possible to reveal pressure recovery, total pressure loss, and the general nature of flow distortion at the AIP.
{"title":"Pressure Equalization Method for Passive Flow Control of an S-Duct Intake for High Subsonic Speeds","authors":"Asad Asghar, Stephen A. Pym, W. Allan, M. Laviolette, R. Stowe","doi":"10.1115/GT2018-75793","DOIUrl":"https://doi.org/10.1115/GT2018-75793","url":null,"abstract":"High subsonic aircraft with fuselage-embedded engines often employ inlet ducts with multiple bends in order to induct ambient air into the propulsion system while also diffusing it to engine-acceptable Mach numbers. Engine performance, stability margin, and safety of the integrated aircraft-engine system can be negatively affected by separated, swirling and distorted flow that often characterizes S-ducts. This paper reports the investigation of a flow control strategy aimed at the improvement of the aerodynamic performance of S-duct diffusers. Passive pressure equalization was employed to reduce the size and intensity of the separated flow downstream of curved duct sections, utilizing naturally occurring pressure differences. Characteristic secondary flows promote instability and contribute to flow separation and losses in the inner radius region of a duct bend. In the present scheme, boundary layer flow upstream of the separation point on the inner radius of the first bend is energized by re-injecting higher momentum air, drawn from the higher pressure region at the outer radius of the same bend. The flow control effectiveness of this passive pressure equalization was evaluated by test-rig measurements of the flow in an S-duct at an inlet Mach number of 0.80. Static surface pressure was measured along the length of the S-duct and the total pressure was measured at the aerodynamic interface plane using a pressure rake with five high performance pressure transducers. It was possible to reveal pressure recovery, total pressure loss, and the general nature of flow distortion at the AIP.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"127 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133877853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Bauer, J. Friedrichs, D. Wulff, C. Werner-Spatz
Aircraft engine maintenance is performed on an on-condition basis. Monitoring the engine condition during operation is important to provide an efficient maintenance. Engine Condition Monitoring has thus become a standard procedure during operation. However, one of the most important parameters, the engine thrust, is not directly measured and can therefore not be monitored, which makes it difficult to distinguish whether deteriorating trends e.g. in fuel comsumption must be attributed to the engine (e.g. due to thermodynamic wear) or to the aircraft (e.g. due to increased drag). Being able to make this distinction would improve troubleshooting and maintenance planning and thus help to reduce the cost of ownership of an aircraft. This paper describes the development and quality assessment of a system for direct engine thrust measurement during the normal engine operation. The system was designed, calibrated and validated with engine test runs. After the necessary certification of the whole system a flight test campaign to validate the system, when installed on an aircraft, was started. In the presented work an assessment of the quality of measured data from the first period of the ongoing flight test is presented.
{"title":"Measurement Quality Assessment of an On-Wing Engine Thrust Measurement System","authors":"M. Bauer, J. Friedrichs, D. Wulff, C. Werner-Spatz","doi":"10.1115/GT2018-76496","DOIUrl":"https://doi.org/10.1115/GT2018-76496","url":null,"abstract":"Aircraft engine maintenance is performed on an on-condition basis. Monitoring the engine condition during operation is important to provide an efficient maintenance. Engine Condition Monitoring has thus become a standard procedure during operation. However, one of the most important parameters, the engine thrust, is not directly measured and can therefore not be monitored, which makes it difficult to distinguish whether deteriorating trends e.g. in fuel comsumption must be attributed to the engine (e.g. due to thermodynamic wear) or to the aircraft (e.g. due to increased drag). Being able to make this distinction would improve troubleshooting and maintenance planning and thus help to reduce the cost of ownership of an aircraft. This paper describes the development and quality assessment of a system for direct engine thrust measurement during the normal engine operation. The system was designed, calibrated and validated with engine test runs. After the necessary certification of the whole system a flight test campaign to validate the system, when installed on an aircraft, was started. In the presented work an assessment of the quality of measured data from the first period of the ongoing flight test is presented.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115441617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Ferrand, M. Bellenoue, Y. Bertin, R. Cirligeanu, Patrick Marconi, F. Mercier-Calvairac
In order to decrease the fuel consumption, a new flight mode is being considered for twin-engine helicopters, in which one engine is put into sleeping mode (a mode in which the gas generator is kept at a stabilized, sub-idle speed by means of an electric motor, with no combustion), while the remaining engine operates at nominal load. The restart of the engine in sleeping mode is therefore deemed critical for safety reasons. This efficient new flight mode has raised the interest in the modeling of the restart of a turboshaft engine. In this context, the initial conditions of the simulations are better known relative to a ground start, in particular the air flow through the gas generator is constant, the fuel and oil system states are known and temperatures of the casings are equal to ambient. During the restart phase of the engine, the gas generator speed is kept at constant speed until the light-up is detected by a rise in inter-turbine temperature, then the starter torque increases, accelerating the engine towards idle speed. In this paper, the modeling of the acceleration of the gas generator from light-up to idle and above idle speeds is presented. Details on the light-up process are not addressed here. The study is based on the high-fidelity aero-thermodynamic restart model that is currently being developed for a 2000 horse power, free turbine turboshaft. In this case, the term high-fidelity refers not only to the modeling of the flow path components but it also includes all the subsystems, secondary air flows and controls with a high level of detail. The physical phenomena governing the acceleration of the turboshaft engine following a restart — mainly the transient evolution of the combustion efficiency and the power loss by heat soakage — are discussed in this paper and modeling solutions are presented. The results of the simulations are compared to engine test data, highlighting that the studied phenomena have an impact on the acceleration of the turboshaft engine and that the model is able to correctly predict acceleration trends.
{"title":"High Fidelity Modeling of the Acceleration of a Turboshaft Engine During a Restart","authors":"A. Ferrand, M. Bellenoue, Y. Bertin, R. Cirligeanu, Patrick Marconi, F. Mercier-Calvairac","doi":"10.1115/GT2018-76654","DOIUrl":"https://doi.org/10.1115/GT2018-76654","url":null,"abstract":"In order to decrease the fuel consumption, a new flight mode is being considered for twin-engine helicopters, in which one engine is put into sleeping mode (a mode in which the gas generator is kept at a stabilized, sub-idle speed by means of an electric motor, with no combustion), while the remaining engine operates at nominal load. The restart of the engine in sleeping mode is therefore deemed critical for safety reasons. This efficient new flight mode has raised the interest in the modeling of the restart of a turboshaft engine.\u0000 In this context, the initial conditions of the simulations are better known relative to a ground start, in particular the air flow through the gas generator is constant, the fuel and oil system states are known and temperatures of the casings are equal to ambient. During the restart phase of the engine, the gas generator speed is kept at constant speed until the light-up is detected by a rise in inter-turbine temperature, then the starter torque increases, accelerating the engine towards idle speed. In this paper, the modeling of the acceleration of the gas generator from light-up to idle and above idle speeds is presented. Details on the light-up process are not addressed here.\u0000 The study is based on the high-fidelity aero-thermodynamic restart model that is currently being developed for a 2000 horse power, free turbine turboshaft. In this case, the term high-fidelity refers not only to the modeling of the flow path components but it also includes all the subsystems, secondary air flows and controls with a high level of detail.\u0000 The physical phenomena governing the acceleration of the turboshaft engine following a restart — mainly the transient evolution of the combustion efficiency and the power loss by heat soakage — are discussed in this paper and modeling solutions are presented. The results of the simulations are compared to engine test data, highlighting that the studied phenomena have an impact on the acceleration of the turboshaft engine and that the model is able to correctly predict acceleration trends.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114851710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The efficacy of integrating the lobed mixer with the core flow deswirling struts to create a single component for reducing the exhaust system length, beyond that attainable through mixer optimization alone, has been investigated. This investigation has been conducted via CFD simulations of a medium-bypass turbofan exhaust system at engine cruise representative conditions. Comparative analysis shows that integration augmented thrust output by about 0.02% while total pressure loss was increased by 3.6%. The aim of the study, to show that this new integrated design would have either minimal impact on or improve exhaust system performance, was confirmed. Comparisons of the flow fields and characteristic quantities downstream of the mixer also showed minimal impact on flow through the nozzle. The deswirling strut was offset by 0.65 Dh axially when integrated with the mixer, therefore it can be concluded that the exhaust system ducting could be reduced in length by this same measure — saving engine weight in the process.
{"title":"On the Efficacy of Integrating Structural Struts With Lobed Mixers in Turbofan Engine Exhaust Systems","authors":"A. Wright, A. Mahallati, M. Conlon, J. Militzer","doi":"10.1115/GT2018-77168","DOIUrl":"https://doi.org/10.1115/GT2018-77168","url":null,"abstract":"The efficacy of integrating the lobed mixer with the core flow deswirling struts to create a single component for reducing the exhaust system length, beyond that attainable through mixer optimization alone, has been investigated. This investigation has been conducted via CFD simulations of a medium-bypass turbofan exhaust system at engine cruise representative conditions. Comparative analysis shows that integration augmented thrust output by about 0.02% while total pressure loss was increased by 3.6%. The aim of the study, to show that this new integrated design would have either minimal impact on or improve exhaust system performance, was confirmed. Comparisons of the flow fields and characteristic quantities downstream of the mixer also showed minimal impact on flow through the nozzle. The deswirling strut was offset by 0.65 Dh axially when integrated with the mixer, therefore it can be concluded that the exhaust system ducting could be reduced in length by this same measure — saving engine weight in the process.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114627493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vadim Kloos, T. H. Speak, R. Sellick, Prof.dr. Peter Jeschke
The effects of high shaft power offtake in a direct drive, a geared drive, and a novel turbofan configuration are investigated. A design and off-design performance analysis shows the configuration specific limitations and advantages. The more electric aircraft (MEA) concept promises to offer advantages with respect to aircraft performance, maintenance and operating costs. The engines for the MEA concept are based on conventional turbofan architectures. These engines are designed for significantly increased shaft power offtake that is required by the airframe, and the shaft power is usually taken off the high-pressure spool. This can impair the off-design performance of the engine and lead to compromises during engine design and to operability limitations. Taking the power off the low-pressure spool mitigates some of the problems but has other limitations. In this work, an alternative novel turbofan architecture is investigated for its potential to avoid the problems related to high shaft power offtakes. This architecture is called the dual drive booster because it uses a summation gearbox to drive the booster from both the low- and high-pressure spool. The shaft power, if taken off the booster spool, is effectively provided by both the low- and high-pressure spools, which allows the provision of very high power levels. This new concept is benchmarked against a two-spool direct drive and a geared drive turbofan. Furthermore, it is described, how the new architecture can incorporate an embedded motor generator. The presented concept mitigates some of the problems which are encountered during high power offtake in conventional configurations. In particular, the core compressors are less affected by a change in shaft power offtake. This allows higher power offtakes and gives more flexibility during engine design and operation. Additionally, the potential to use the new configuration as a gas turbine-electric hybrid engine is assessed, where electrical power boost is applied during critical flight phases. The ability to convert additional shaft power is compared with conventional configurations. Here, the new configuration also shows superior behavior because the core compressors are significantly less affected by power input than in conventional configurations. The spool speed and its variation is more suitable for electrical machines than in conventional configuration with low-pressure spool power transfer. The dual drive booster concept is particularly suited for applications with high shaft power offtakes and inputs, and should be considered for propulsion of more electric aircrafts.
{"title":"Dual Drive Booster for a Two-Spool Turbofan: High Shaft Power Offtake Capability for MEA and Hybrid Aircraft Concepts","authors":"Vadim Kloos, T. H. Speak, R. Sellick, Prof.dr. Peter Jeschke","doi":"10.1115/GT2018-75501","DOIUrl":"https://doi.org/10.1115/GT2018-75501","url":null,"abstract":"The effects of high shaft power offtake in a direct drive, a geared drive, and a novel turbofan configuration are investigated. A design and off-design performance analysis shows the configuration specific limitations and advantages.\u0000 The more electric aircraft (MEA) concept promises to offer advantages with respect to aircraft performance, maintenance and operating costs. The engines for the MEA concept are based on conventional turbofan architectures. These engines are designed for significantly increased shaft power offtake that is required by the airframe, and the shaft power is usually taken off the high-pressure spool. This can impair the off-design performance of the engine and lead to compromises during engine design and to operability limitations. Taking the power off the low-pressure spool mitigates some of the problems but has other limitations. In this work, an alternative novel turbofan architecture is investigated for its potential to avoid the problems related to high shaft power offtakes. This architecture is called the dual drive booster because it uses a summation gearbox to drive the booster from both the low- and high-pressure spool. The shaft power, if taken off the booster spool, is effectively provided by both the low- and high-pressure spools, which allows the provision of very high power levels. This new concept is benchmarked against a two-spool direct drive and a geared drive turbofan. Furthermore, it is described, how the new architecture can incorporate an embedded motor generator. The presented concept mitigates some of the problems which are encountered during high power offtake in conventional configurations. In particular, the core compressors are less affected by a change in shaft power offtake. This allows higher power offtakes and gives more flexibility during engine design and operation. Additionally, the potential to use the new configuration as a gas turbine-electric hybrid engine is assessed, where electrical power boost is applied during critical flight phases. The ability to convert additional shaft power is compared with conventional configurations. Here, the new configuration also shows superior behavior because the core compressors are significantly less affected by power input than in conventional configurations. The spool speed and its variation is more suitable for electrical machines than in conventional configuration with low-pressure spool power transfer.\u0000 The dual drive booster concept is particularly suited for applications with high shaft power offtakes and inputs, and should be considered for propulsion of more electric aircrafts.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114695165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Compressors are crucial to the efficient operation of a gas turbine; however, fouling, caused by adherence of particles to surfaces, can have a negative effect on compressor performance. In this study, a NASA Stage 35 single-stage axial-flow compressor was employed as the model for numerical simulation using the ANSYS CFX software of the effects caused by mild and severe fouling under salt fog scale. To measure these effects, two distinct models were used. For mild fouling, the simulated stator blade surface roughness was altered nonuniformly; for severe fouling, the simulated stator blade thick-ness was altered. Results indicated that surface roughness caused by mild fouling only has a small effect on compressor performance and no effect on the stable working range. However, changes in the blade thickness as a result of severe fouling have a large effect on compressor performance and a clear effect on the stability of the compressor’s working range. The fouling causes an increase in the boundary layer at the trailing edge of the suction side of the blade thereby increasing the loss of flow; fouling effect after emergence angle, wide design value, and increasing blade of circumferential stress.
{"title":"Study on the Performance Variation of Compressor Under Salt Fog Scale","authors":"Sun Hai-ou, Li-Song Wang, Lei Wan, Feng Qu","doi":"10.1115/GT2018-75981","DOIUrl":"https://doi.org/10.1115/GT2018-75981","url":null,"abstract":"Compressors are crucial to the efficient operation of a gas turbine; however, fouling, caused by adherence of particles to surfaces, can have a negative effect on compressor performance. In this study, a NASA Stage 35 single-stage axial-flow compressor was employed as the model for numerical simulation using the ANSYS CFX software of the effects caused by mild and severe fouling under salt fog scale. To measure these effects, two distinct models were used. For mild fouling, the simulated stator blade surface roughness was altered nonuniformly; for severe fouling, the simulated stator blade thick-ness was altered. Results indicated that surface roughness caused by mild fouling only has a small effect on compressor performance and no effect on the stable working range. However, changes in the blade thickness as a result of severe fouling have a large effect on compressor performance and a clear effect on the stability of the compressor’s working range. The fouling causes an increase in the boundary layer at the trailing edge of the suction side of the blade thereby increasing the loss of flow; fouling effect after emergence angle, wide design value, and increasing blade of circumferential stress.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128210581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High-speed train is developing popular in China, which provides the convenient and fast transportation way, comparable to plane. The moving direction and speed of high-speed train is decided by the traction motor. Generally, a coaxial centrifugal fan is used to cool the motor and assemble in the motor casing. To ensure the reliability of the traction motor, more and more attention is paid to improve the performance of cooling fans in a wide range of rotating speed. As the train is designed to move in both directions, the traction motor is designed to rotate in both directions, so does the coaxial motor cooling fan. Symmetrical and straight blade structure is adopted to get the same performance of the fan in both forward and reverse moving directions. Therefore, the aerodynamic performance of the cooling fan is relatively not good enough, which results in relatively high aerodynamic noise. In order to analyze the cooling fan aerodynamic performance and aerodynamic noise, CFD method was performed on the full 3D model with the impeller-casing clearance. The acoustic analogy method was used to analyze the noise of the centrifugal cooling fan. In addition, the aerodynamic noise of the motor with the cooling fan was tested at different rotating speed in the semi-anechoic lab. The CFD method is verified and the results are in good agreement with the experimental results. The results show that it is necessary to consider the effects of impeller-casing leakage and the vacuum inlet condition in the simulated model to get its more accurate performance. Modified CFD model of the cooling fan was proposed here. It is suggested that the modified structure of the casing can be used to improve the performance of the cooling fan and reduce the corresponding aerodynamic noise.
{"title":"Numerical and Experimental Investigation on Centrifugal Cooling Fan in a Traction Motor","authors":"X. Qu, J. Tian, Tong Wang","doi":"10.1115/GT2018-76659","DOIUrl":"https://doi.org/10.1115/GT2018-76659","url":null,"abstract":"High-speed train is developing popular in China, which provides the convenient and fast transportation way, comparable to plane. The moving direction and speed of high-speed train is decided by the traction motor. Generally, a coaxial centrifugal fan is used to cool the motor and assemble in the motor casing. To ensure the reliability of the traction motor, more and more attention is paid to improve the performance of cooling fans in a wide range of rotating speed. As the train is designed to move in both directions, the traction motor is designed to rotate in both directions, so does the coaxial motor cooling fan. Symmetrical and straight blade structure is adopted to get the same performance of the fan in both forward and reverse moving directions. Therefore, the aerodynamic performance of the cooling fan is relatively not good enough, which results in relatively high aerodynamic noise. In order to analyze the cooling fan aerodynamic performance and aerodynamic noise, CFD method was performed on the full 3D model with the impeller-casing clearance. The acoustic analogy method was used to analyze the noise of the centrifugal cooling fan. In addition, the aerodynamic noise of the motor with the cooling fan was tested at different rotating speed in the semi-anechoic lab. The CFD method is verified and the results are in good agreement with the experimental results. The results show that it is necessary to consider the effects of impeller-casing leakage and the vacuum inlet condition in the simulated model to get its more accurate performance. Modified CFD model of the cooling fan was proposed here. It is suggested that the modified structure of the casing can be used to improve the performance of the cooling fan and reduce the corresponding aerodynamic noise.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130166576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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