Asad Asghar, W. Allan, M. Laviolette, R. Stowe, D. Alexander, G. Ingram
This paper reports the internal performance evaluation of S-duct diffusers with different offset-to-length ratios. The geometric parameters of S-duct diffusers are currently of great interest because of increasing demand for stealth and consequently, their effects on drag and aero-engine stability margin. The generic S-duct diffuser selected as a baseline had a rectangular-entrance and circular exit. Test articles were tested with the high subsonic, Ma = 0.8 and 0.85, flow and were manufactured using 3D printing. stream-wise static pressure and exit-plane total pressure were measured in a test rig using surface pressure taps and a 5-probe rotating rake, respectively. The baseline and variant S-ducts were also simulated through computational fluid dynamics. The investigation indicated the presence of stream-wise and circumferential pressure gradients leading to a separated flow in the S-duct diffusers and distortion at the exit plane. The static pressure recovery decreased and total pressure loss increased with an increase in the offset-to-length ratio. The circumferential distortion at the engine face clearly indicated a trend with respect to the offset-to-length ratio, however radial distortion did not.
{"title":"S-Duct Diffuser Offset-to-Length Ratio Effect on Aerodynamic Performance of Propulsion-System Inlet of High Speed Aircraft","authors":"Asad Asghar, W. Allan, M. Laviolette, R. Stowe, D. Alexander, G. Ingram","doi":"10.1115/GT2018-76661","DOIUrl":"https://doi.org/10.1115/GT2018-76661","url":null,"abstract":"This paper reports the internal performance evaluation of S-duct diffusers with different offset-to-length ratios. The geometric parameters of S-duct diffusers are currently of great interest because of increasing demand for stealth and consequently, their effects on drag and aero-engine stability margin. The generic S-duct diffuser selected as a baseline had a rectangular-entrance and circular exit. Test articles were tested with the high subsonic, Ma = 0.8 and 0.85, flow and were manufactured using 3D printing. stream-wise static pressure and exit-plane total pressure were measured in a test rig using surface pressure taps and a 5-probe rotating rake, respectively. The baseline and variant S-ducts were also simulated through computational fluid dynamics. The investigation indicated the presence of stream-wise and circumferential pressure gradients leading to a separated flow in the S-duct diffusers and distortion at the exit plane. The static pressure recovery decreased and total pressure loss increased with an increase in the offset-to-length ratio. The circumferential distortion at the engine face clearly indicated a trend with respect to the offset-to-length ratio, however radial distortion did not.","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":"122436608","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}
Martin Berthold, H. Morvan, R. Jefferson-Loveday, B. Rothwell, C. Young
High loads and bearing life requirements make journal bearings a potential choice for use in high power, epicyclic gearboxes in jet engines. Particularly in a planetary configuration the kinematic conditions are complex. With the planet gears rotating about their own axis and orbiting around the sun gear, centrifugal forces generated by both motions interact with each other and affect the external flow behavior of the oil exiting the journal bearing. Computational Fluid Dynamics (CFD) simulations using the Volume of Fluid (VoF) method are carried out in ANSYS Fluent [1] to numerically model the two-phase flow behavior of the oil exiting the bearing and merging into the air surrounding the bearing. This paper presents an investigation of two numerical schemes that are available in ANSYS Fluent to track or capture the air-oil phase interface: the geometric reconstruction scheme and the compressive scheme. Both numerical schemes are used to model the oil outflow behavior in the most simplistic approximation of a journal bearing: a representation, rotating about its own axis, with a circumferentially constant, i.e. concentric, lubricating gap. Based on these simplifications, a three dimensional (3D) CFD sector model with rotationally periodic boundaries is considered. A comparison of the geometric reconstruction scheme and the compressive scheme is presented with regards to the accuracy of the phase interface reconstruction and the time required to reach steady state flow field conditions. The CFD predictions are validated against existing literature data with respect to the flow regime, the direction of the predicted oil flow path and the oil film thickness. Based on the findings and considerations of industrial requirements, a recommendation is made for the most suitable scheme to be used. With a robust and partially validated CFD model in place, the model fidelity can be enhanced to include journal bearing eccentricity. Due to the convergent-divergent gap and the resultant pressure field within the lubricating oil film, the outflow behavior can be expected to be very different compared to that of a concentric journal bearing. Naturally, the inlet boundary conditions for the oil emerging from the journal bearing into the external environment must be consistent with the outlet conditions from the bearing. The second part of this paper therefore focuses on providing a method to generate appropriate inlet boundary conditions for external oil flow from an eccentric journal bearing.
{"title":"Multiphase CFD Modeling of External Oil Flow From a Journal Bearing","authors":"Martin Berthold, H. Morvan, R. Jefferson-Loveday, B. Rothwell, C. Young","doi":"10.1115/GT2018-77130","DOIUrl":"https://doi.org/10.1115/GT2018-77130","url":null,"abstract":"High loads and bearing life requirements make journal bearings a potential choice for use in high power, epicyclic gearboxes in jet engines. Particularly in a planetary configuration the kinematic conditions are complex. With the planet gears rotating about their own axis and orbiting around the sun gear, centrifugal forces generated by both motions interact with each other and affect the external flow behavior of the oil exiting the journal bearing.\u0000 Computational Fluid Dynamics (CFD) simulations using the Volume of Fluid (VoF) method are carried out in ANSYS Fluent [1] to numerically model the two-phase flow behavior of the oil exiting the bearing and merging into the air surrounding the bearing.\u0000 This paper presents an investigation of two numerical schemes that are available in ANSYS Fluent to track or capture the air-oil phase interface: the geometric reconstruction scheme and the compressive scheme. Both numerical schemes are used to model the oil outflow behavior in the most simplistic approximation of a journal bearing: a representation, rotating about its own axis, with a circumferentially constant, i.e. concentric, lubricating gap. Based on these simplifications, a three dimensional (3D) CFD sector model with rotationally periodic boundaries is considered.\u0000 A comparison of the geometric reconstruction scheme and the compressive scheme is presented with regards to the accuracy of the phase interface reconstruction and the time required to reach steady state flow field conditions. The CFD predictions are validated against existing literature data with respect to the flow regime, the direction of the predicted oil flow path and the oil film thickness. Based on the findings and considerations of industrial requirements, a recommendation is made for the most suitable scheme to be used.\u0000 With a robust and partially validated CFD model in place, the model fidelity can be enhanced to include journal bearing eccentricity. Due to the convergent-divergent gap and the resultant pressure field within the lubricating oil film, the outflow behavior can be expected to be very different compared to that of a concentric journal bearing. Naturally, the inlet boundary conditions for the oil emerging from the journal bearing into the external environment must be consistent with the outlet conditions from the bearing. The second part of this paper therefore focuses on providing a method to generate appropriate inlet boundary conditions for external oil flow from an eccentric journal bearing.","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":"129868468","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}
Intake and exhaust system is one of the important parts of power systems of the ships, because the resistance performance will influence the whole performance of the main propulsion engine. Therefore, the performance of the intake and exhaust systems are always studied in advance inside laboratories before they are built as the real ship system. In this paper, both CFD and experiment methods are employed to investigate the pressure loss performance of intake and exhaust systems. The RANS simulation with k-ε turbulence model is done by the commercial code ANSYS Fluent. Firstly, sixteen different intake and exhaust models were calculated with the proper boundary conditions according to the former research experience. The resistance performance of the real ship intake and exhaust models was obtained. Then a simplified geometric model was proposed to simulate the performance of the complex real ship intake and exhaust system effectively and efficiently. This kind of novel simplified model can reproduce the geometrical structures of the real ship under lab environments, which can easily adjust the angle of the resistance simulators. Additionally, a low speed wind tunnel system with a kind of small-scale aerodynamic model has been made and its pressure loss performance was measured under laboratory conditions in the experiment. Finally, the simulation results are compared with the experimental data. The results show that the simulation method employed in this paper is suitable to do such research work with high accuracy. And the simplified model can be used to mimic the resistance performance of the real ship intake and exhaust systems.
{"title":"A Novel Method of Intake and Exhausts System Simulators for Real Marine Engine Under Lab Conditions","authors":"Y. Luan, Lianfeng Yang, Yonglei Qu","doi":"10.1115/GT2018-76043","DOIUrl":"https://doi.org/10.1115/GT2018-76043","url":null,"abstract":"Intake and exhaust system is one of the important parts of power systems of the ships, because the resistance performance will influence the whole performance of the main propulsion engine. Therefore, the performance of the intake and exhaust systems are always studied in advance inside laboratories before they are built as the real ship system. In this paper, both CFD and experiment methods are employed to investigate the pressure loss performance of intake and exhaust systems. The RANS simulation with k-ε turbulence model is done by the commercial code ANSYS Fluent. Firstly, sixteen different intake and exhaust models were calculated with the proper boundary conditions according to the former research experience. The resistance performance of the real ship intake and exhaust models was obtained. Then a simplified geometric model was proposed to simulate the performance of the complex real ship intake and exhaust system effectively and efficiently. This kind of novel simplified model can reproduce the geometrical structures of the real ship under lab environments, which can easily adjust the angle of the resistance simulators. Additionally, a low speed wind tunnel system with a kind of small-scale aerodynamic model has been made and its pressure loss performance was measured under laboratory conditions in the experiment. Finally, the simulation results are compared with the experimental data. The results show that the simulation method employed in this paper is suitable to do such research work with high accuracy. And the simplified model can be used to mimic the resistance performance of the real ship intake and exhaust systems.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"44 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":"134471529","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}
Intercooled recuperated turbofan engines with high bypass ratio are becoming a research focus in recent years due to its advantages of relatively better fuel economy, lower emission and noise characteristic. The re-heater can recover waste heat in the exhaust gas downstream of the low pressure turbine to reduce the specific fuel consumption, and the intercooler can improve compression ability of the compressors with sufficient temperature difference between the high pressure compressor and the low pressure turbine. An optimal pressure ratio split is often sought to maximize the effect of the intercooler on improving the compression ability of the compressors. To determine an optimal pressure ratio split, different combinations of pressure ratio between high and low pressure spools must be calculated, and this requires huge amount of work with the traditional method to achieve the suitable cycle selections. In this paper, theoretic thermodynamic analysis is carried out to derive an explicit solution of the optimum pressure ratio split for maximizing the efficiency of the whole compression path. The effects of different variables on the optimum pressure ratio split are investigated according to the correlated variables in the solution function. A comparison calculation is also made to validate the effectiveness and accuracy of the explicit solution. The results show that the optimum pressure ratio split can be achieved with the derived solution function, which will significantly simplify the process of the cycle parameter selection.
{"title":"Thermodynamic Analysis on Optimum Pressure Ratio Split of Intercooled Recuperated Turbofan Engines","authors":"Hualei Li, Zhiyong Tan","doi":"10.1115/GT2018-76121","DOIUrl":"https://doi.org/10.1115/GT2018-76121","url":null,"abstract":"Intercooled recuperated turbofan engines with high bypass ratio are becoming a research focus in recent years due to its advantages of relatively better fuel economy, lower emission and noise characteristic. The re-heater can recover waste heat in the exhaust gas downstream of the low pressure turbine to reduce the specific fuel consumption, and the intercooler can improve compression ability of the compressors with sufficient temperature difference between the high pressure compressor and the low pressure turbine. An optimal pressure ratio split is often sought to maximize the effect of the intercooler on improving the compression ability of the compressors. To determine an optimal pressure ratio split, different combinations of pressure ratio between high and low pressure spools must be calculated, and this requires huge amount of work with the traditional method to achieve the suitable cycle selections. In this paper, theoretic thermodynamic analysis is carried out to derive an explicit solution of the optimum pressure ratio split for maximizing the efficiency of the whole compression path. The effects of different variables on the optimum pressure ratio split are investigated according to the correlated variables in the solution function. A comparison calculation is also made to validate the effectiveness and accuracy of the explicit solution. The results show that the optimum pressure ratio split can be achieved with the derived solution function, which will significantly simplify the process of the cycle parameter selection.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"46 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":"114262902","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, S. Sidhu, W. Allan, G. Ingram, Tom Hickling, R. Stowe
S-Ducts have wide application on air vehicles with embedded engines. The complex geometry is known to lead to separation downstream of curved profiles. This paper reports the influences on that flow of passive flow control geometries. In these experiments, stream-wise tubercles were applied in an effort to improve the internal performance of S-duct diffusers, parameters including pressure recovery, distortion and swirl. The test articles were tested with the high subsonic (Ma = 0.8) flow and were manufactured using 3D printing. Stream-wise static pressure and exit-plane total pressure were measured in a test rig using surface pressure taps and a 5-probe rotating rake, respectively; the baseline and variant S-ducts were simulated through computational fluid dynamics. The experiments showed that some subtle improvements to the S-Duct distortion could be achieved through careful selection of tubercle geometry. Generally, the recovered flow downstream of the inner radius of the second bend of the S-duct deteriorated, but overall pressure recovery improved. The simulations were useful in characterizing swirl, whereas experiments were not so equipped. Adjustments to the numerical approaches resulted in reasonable agreement with the experiments.
{"title":"Investigation of a Passive Flow Control Device in an S-Duct Inlet of a Propulsion System With High Subsonic Flow","authors":"Asad Asghar, S. Sidhu, W. Allan, G. Ingram, Tom Hickling, R. Stowe","doi":"10.1115/GT2018-76636","DOIUrl":"https://doi.org/10.1115/GT2018-76636","url":null,"abstract":"S-Ducts have wide application on air vehicles with embedded engines. The complex geometry is known to lead to separation downstream of curved profiles. This paper reports the influences on that flow of passive flow control geometries. In these experiments, stream-wise tubercles were applied in an effort to improve the internal performance of S-duct diffusers, parameters including pressure recovery, distortion and swirl. The test articles were tested with the high subsonic (Ma = 0.8) flow and were manufactured using 3D printing. Stream-wise static pressure and exit-plane total pressure were measured in a test rig using surface pressure taps and a 5-probe rotating rake, respectively; the baseline and variant S-ducts were simulated through computational fluid dynamics. The experiments showed that some subtle improvements to the S-Duct distortion could be achieved through careful selection of tubercle geometry. Generally, the recovered flow downstream of the inner radius of the second bend of the S-duct deteriorated, but overall pressure recovery improved. The simulations were useful in characterizing swirl, whereas experiments were not so equipped. Adjustments to the numerical approaches resulted in reasonable agreement with the experiments.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"24 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":"115741434","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}
Inlet distortion often occurs at off-design points when flow separates within an intake. This unsteady phenomenon could seriously impact fan performance. Fan-distortion interaction is a highly unsteady aerodynamic phenomenon. High-fidelity simulation can provide a detailed insight into these interactions. However, due to computational resource limitations, the use of eddy resolving methods for a fully resolved fan calculation is currently infeasible for industry. To solve this problem, a mixed-fidelity CFD method is proposed. This method uses the Large Eddy Simulation (LES) to resolve the turbulence associated with separation, and the Immersed Boundary Method with Smeared Geometry (IBMSG) for the fan. The method is validated by an experiment of Darmstadt Rotor, which shows a good agreement in terms of total pressure distributions. A detailed investigation is then conducted on a subsonic rotor with an annular beam generating inlet distortion. A range of studies are performed to investigate fan influence on distortions. Compared to the case without fan, it shows that a fan has a significant effect in reducing distortions. Three fan locations are examined. The fan nearer to the inlet tends to have a higher pressure recovery. Three beams with different heights are also tested to generate various degrees of distortions. The results indicate that the fan can suppress the distortions and its recovery effect is proportional to the degree of inlet distortion.
{"title":"A Mixed-Fidelity Numerical Study for Fan-Distortion Interaction","authors":"Yunfei Ma, J. Cui, N. R. Vadlamani, P. Tucker","doi":"10.1115/GT2018-75090","DOIUrl":"https://doi.org/10.1115/GT2018-75090","url":null,"abstract":"Inlet distortion often occurs at off-design points when flow separates within an intake. This unsteady phenomenon could seriously impact fan performance. Fan-distortion interaction is a highly unsteady aerodynamic phenomenon. High-fidelity simulation can provide a detailed insight into these interactions. However, due to computational resource limitations, the use of eddy resolving methods for a fully resolved fan calculation is currently infeasible for industry. To solve this problem, a mixed-fidelity CFD method is proposed. This method uses the Large Eddy Simulation (LES) to resolve the turbulence associated with separation, and the Immersed Boundary Method with Smeared Geometry (IBMSG) for the fan. The method is validated by an experiment of Darmstadt Rotor, which shows a good agreement in terms of total pressure distributions.\u0000 A detailed investigation is then conducted on a subsonic rotor with an annular beam generating inlet distortion. A range of studies are performed to investigate fan influence on distortions. Compared to the case without fan, it shows that a fan has a significant effect in reducing distortions. Three fan locations are examined. The fan nearer to the inlet tends to have a higher pressure recovery. Three beams with different heights are also tested to generate various degrees of distortions. The results indicate that the fan can suppress the distortions and its recovery effect is proportional to the degree of inlet distortion.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"24 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":"116426905","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}
Maintenance costs are a substantial contributor to airline operating costs. In this context, understanding, analyzing, and predicting engine performance deterioration is crucial. While diagnostic methods for analyzing the current module and overall engine condition are established in state-of-the-art engine condition monitoring (ECM) systems, deterioration modeling and prognosis are still fields of research. The identification of the contribution of deterioration mechanisms, such as fouling, erosion, and abrasion, to the in-service deterioration poses a key challenge in this area. This paper focuses on a top-down approach for the high pressure compressor (HPC) module. The selected approach is to quantify the contribution of individual deterioration mechanisms to the overall HPC efficiency deterioration based on in-flight measurements. This is accomplished by first using the in-flight measurements to analyze the HPC efficiency loss. Then, the resulting time series of the analyzed HPC efficiency loss are preprocessed. Finally, models of the deterioration mechanisms are fitted to the preprocessed time series. The deterioration models are chosen based on literature references to the respective deterioration mechanisms. As multiple influencing factors affect the deterioration mechanisms, a fleet analysis is conducted to select the model inputs. The fitting process involves a parametric nonlinear regression problem. The outcome is an estimation of the evolution of the deterioration mechanisms over time. This methodology is used to evaluate all available in-service engines of the same type and fleet and to define a fleet model. In the final step, benefits and limitations of the fleet model are investigated.
{"title":"A Top-Down Approach for Quantifying the Contribution of High Pressure Compressor Deterioration Mechanisms to the Performance Deterioration of Turbofan Engines","authors":"H. Vogel, André Kando, H. Schulte, S. Staudacher","doi":"10.1115/GT2018-75558","DOIUrl":"https://doi.org/10.1115/GT2018-75558","url":null,"abstract":"Maintenance costs are a substantial contributor to airline operating costs. In this context, understanding, analyzing, and predicting engine performance deterioration is crucial. While diagnostic methods for analyzing the current module and overall engine condition are established in state-of-the-art engine condition monitoring (ECM) systems, deterioration modeling and prognosis are still fields of research. The identification of the contribution of deterioration mechanisms, such as fouling, erosion, and abrasion, to the in-service deterioration poses a key challenge in this area. This paper focuses on a top-down approach for the high pressure compressor (HPC) module. The selected approach is to quantify the contribution of individual deterioration mechanisms to the overall HPC efficiency deterioration based on in-flight measurements. This is accomplished by first using the in-flight measurements to analyze the HPC efficiency loss. Then, the resulting time series of the analyzed HPC efficiency loss are preprocessed. Finally, models of the deterioration mechanisms are fitted to the preprocessed time series. The deterioration models are chosen based on literature references to the respective deterioration mechanisms. As multiple influencing factors affect the deterioration mechanisms, a fleet analysis is conducted to select the model inputs. The fitting process involves a parametric nonlinear regression problem. The outcome is an estimation of the evolution of the deterioration mechanisms over time. This methodology is used to evaluate all available in-service engines of the same type and fleet and to define a fleet model. In the final step, benefits and limitations of the fleet model are investigated.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"136 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":"122776142","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}
Gino Angelini, Tommaso Bonanni, A. Corsini, G. Delibra, L. Tieghi, David Volponi
Heat exchange in air-cooled condensers (ACC) is achieved by forced convection of fresh air on bundle of tubes by means of forced-draft axial-flow fans. These fans are characterized by low solidity and low hub ratio, large diameters, relatively low rotational velocity, high efficiencies. This combination usually leads to fans with non-stalling characteristics, with pressure rise continuously rising when reducing the flow rate, at least in standard (ISO or AMCA) test rigs. In real-life installations, in fact, it is quite difficult to characterize these fans, due to the practical difficulties arising in setting up a proper test rig and to control the boundary conditions of the system, in particular the fan inflow conditions. Here we focus on a real-life setting of ACC, numerically simulated with URANS. In this work the fan is simulated with a Synthetic Blade Model presented in [1]. This model is derived from actuator disk theory, and allows to simulate the unsteady movement of the blades and compute a non-constant azimuthal distribution of lift and drag forces, partially accounting for non-constant deviation in the blade-to-blade passage, while drastically reducing the mesh requirements. In this way it is possible to model the shedding of wakes behind the blades and their interaction with the heat exchanger. The flow will be assumed to be incompressible, due to the low Mach number and heat transfer will be treated assuming temperature to be a passive scalar convected by the flow. Duty point of the fan and heat exchange in the ACC will be studied while inflow conditions, in order to account for free inflow with a constant velocity distribution as well as distortions due to lateral wind. Computations will be carried out on the Virtual Test Rig of developed at Sapienza within the OpenFOAM 2.3.x library with a URANS approach and k-ε closure.
{"title":"Effects of Fan Inflow Distortions on Heat Exchange in Air-Cooled Condensers: Unsteady Computations With Synthetic Blade Model","authors":"Gino Angelini, Tommaso Bonanni, A. Corsini, G. Delibra, L. Tieghi, David Volponi","doi":"10.1115/GT2018-76518","DOIUrl":"https://doi.org/10.1115/GT2018-76518","url":null,"abstract":"Heat exchange in air-cooled condensers (ACC) is achieved by forced convection of fresh air on bundle of tubes by means of forced-draft axial-flow fans. These fans are characterized by low solidity and low hub ratio, large diameters, relatively low rotational velocity, high efficiencies. This combination usually leads to fans with non-stalling characteristics, with pressure rise continuously rising when reducing the flow rate, at least in standard (ISO or AMCA) test rigs. In real-life installations, in fact, it is quite difficult to characterize these fans, due to the practical difficulties arising in setting up a proper test rig and to control the boundary conditions of the system, in particular the fan inflow conditions.\u0000 Here we focus on a real-life setting of ACC, numerically simulated with URANS. In this work the fan is simulated with a Synthetic Blade Model presented in [1]. This model is derived from actuator disk theory, and allows to simulate the unsteady movement of the blades and compute a non-constant azimuthal distribution of lift and drag forces, partially accounting for non-constant deviation in the blade-to-blade passage, while drastically reducing the mesh requirements. In this way it is possible to model the shedding of wakes behind the blades and their interaction with the heat exchanger. The flow will be assumed to be incompressible, due to the low Mach number and heat transfer will be treated assuming temperature to be a passive scalar convected by the flow.\u0000 Duty point of the fan and heat exchange in the ACC will be studied while inflow conditions, in order to account for free inflow with a constant velocity distribution as well as distortions due to lateral wind. Computations will be carried out on the Virtual Test Rig of developed at Sapienza within the OpenFOAM 2.3.x library with a URANS approach and k-ε closure.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"12 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":"124815464","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}
With a continuous annual growth of air traffic by nearly 5%, an additional paradigm change towards industrially producible products is necessary to meet future demands of new airplanes and aero engines. To ensure the producibility of more and more sophisticated aero engines, an assessment of assemblability and disassemblability during preliminary design becomes necessary in this context. Major cost drivers can be identified at an early stage in the product development process regarding assembly-feasible design of the product and the corresponding assembly system. This paper introduces a 3D preliminary design model and a methodology to assess the assemblability and disassemblability of civil aero engines during preliminary design. Based on a systematic evaluation of three different variants of low-pressure turbine modules, implications for a reduction of the assembly and disassembly time can be deduced. Hence, optimization potentials for product design as well as for the design of the corresponding assembly system are identified. The generic models and parametric evaluation methodology of the presented approach allow an application on further aero engine modules, new aero engine technologies as well as other fields.
{"title":"The Assessment of Assemblability and Dissassemblability of Aero Engines During Preliminary Design","authors":"J. Mall, S. Staudacher, C. Koch","doi":"10.1115/GT2018-75615","DOIUrl":"https://doi.org/10.1115/GT2018-75615","url":null,"abstract":"With a continuous annual growth of air traffic by nearly 5%, an additional paradigm change towards industrially producible products is necessary to meet future demands of new airplanes and aero engines. To ensure the producibility of more and more sophisticated aero engines, an assessment of assemblability and disassemblability during preliminary design becomes necessary in this context. Major cost drivers can be identified at an early stage in the product development process regarding assembly-feasible design of the product and the corresponding assembly system. This paper introduces a 3D preliminary design model and a methodology to assess the assemblability and disassemblability of civil aero engines during preliminary design. Based on a systematic evaluation of three different variants of low-pressure turbine modules, implications for a reduction of the assembly and disassembly time can be deduced. Hence, optimization potentials for product design as well as for the design of the corresponding assembly system are identified. The generic models and parametric evaluation methodology of the presented approach allow an application on further aero engine modules, new aero engine technologies as well as other fields.","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":"115002588","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}
This work details an analytical assessment of heat generation in a turbine aero-engine main-shaft bearing and the development of a model to predict that heat generation. The new model is based on an empirical model, previously developed by the Air Force Research Laboratory (AFRL), which features physics based terms multiplied by empirical regression coefficients. That model proved to be limited in that portions of the terms were essentially an extension of the regression coefficients due to the fact that the experimental data was limited to that of one bearing. Additionally, there were separate models for each rolling element material. To develop the new model, the validated bearing analysis code ADORE was used to generate power loss data for angular contact ball bearings of various sizes. The effects of speed, thrust load, pitch diameter, element diameter, number of rolling elements, lubricant inlet temperature, lubricant flow rate, and rolling element material (AISI M50 bearing steel and silicon nitride) are examined. Speed and thrust load are addressed at four levels each. Number of elements, bore diameter, and element diameter as well as lubricant temperature and flow rate are each addressed at three levels. These effects are captured in the model through traction (friction), churning (drag), and shearing (viscous) terms and their respective regression coefficients. The material effect is address through the use of an effective elastic modulus within an estimate of raceway to rolling element contact area. The performance of the model was then compared with experimental data collected in the AFRL High Mach Engine (HME) Bearing Rig. The model created in this work provides designers with an effective tool to examine bearing heat generation during the early engine design phases, avoiding the significant computational and front end expense of other, more detailed methods.
{"title":"Heat Generation in a Main-Shaft Turbine Aero-Engine Bearing Considering Metal and Ceramic Rolling Elements","authors":"Brian D. Nicholson, Jeremy T. Nickell","doi":"10.1115/GT2018-75851","DOIUrl":"https://doi.org/10.1115/GT2018-75851","url":null,"abstract":"This work details an analytical assessment of heat generation in a turbine aero-engine main-shaft bearing and the development of a model to predict that heat generation. The new model is based on an empirical model, previously developed by the Air Force Research Laboratory (AFRL), which features physics based terms multiplied by empirical regression coefficients. That model proved to be limited in that portions of the terms were essentially an extension of the regression coefficients due to the fact that the experimental data was limited to that of one bearing. Additionally, there were separate models for each rolling element material. To develop the new model, the validated bearing analysis code ADORE was used to generate power loss data for angular contact ball bearings of various sizes. The effects of speed, thrust load, pitch diameter, element diameter, number of rolling elements, lubricant inlet temperature, lubricant flow rate, and rolling element material (AISI M50 bearing steel and silicon nitride) are examined. Speed and thrust load are addressed at four levels each. Number of elements, bore diameter, and element diameter as well as lubricant temperature and flow rate are each addressed at three levels. These effects are captured in the model through traction (friction), churning (drag), and shearing (viscous) terms and their respective regression coefficients. The material effect is address through the use of an effective elastic modulus within an estimate of raceway to rolling element contact area. The performance of the model was then compared with experimental data collected in the AFRL High Mach Engine (HME) Bearing Rig. The model created in this work provides designers with an effective tool to examine bearing heat generation during the early engine design phases, avoiding the significant computational and front end expense of other, more detailed methods.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"40 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":"115142238","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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