T. Ishii, K. Nagai, H. Oinuma, R. Kagaya, T. Oishi
This paper describes an experimental study on the acoustic performance when mixer nozzles were applied to the core of a subscale turbofan engine. The primary concern of the mixer nozzle is how to satisfy both less jet mixing noise emission and minimum impact on engine performance parameters such as thrust and fuel consumption. A notched nozzle, a nozzle with tiny dents on the trailing edge, initiates small disturbances in the shear layer, weakens the shear stress, and suppresses jet noise. The Japan Aerospace Exploration Agency (JAXA) and IHI Corporation have studied notched nozzles and found that finer and more notches are preferable for both acoustic and aerodynamic performance. As a next step, it is necessary to maintain the tradeoff between noise suppression and impact on engine performance. To evaluate both the acoustic and aerodynamic performance with the notched nozzle, a subscale turbofan engine, DGEN380, was adopted as a demonstration engine. Experiments with this engine were conducted both in a test cell and in an open test site. The notched nozzle, together with a baseline conical nozzle and a referential serrated nozzle, i.e., a chevron nozzle, was applied to the core exhaust of the engine. The experiment in the test cell clarified that the notched nozzle possibly provides better thrust specific fuel consumption than the referential chevron nozzle. The acoustic measurement in the open environment confirmed that the notched nozzle has the noise suppression characteristics expected from previous test results. The perceived noise levels are attenuated by 1.5 dB, which is the same as or better than the referential mixer nozzle.
{"title":"Experimental Study on Acoustic Performances of Notched Nozzle Using a Subscale Turbofan Engine","authors":"T. Ishii, K. Nagai, H. Oinuma, R. Kagaya, T. Oishi","doi":"10.1115/GT2018-76713","DOIUrl":"https://doi.org/10.1115/GT2018-76713","url":null,"abstract":"This paper describes an experimental study on the acoustic performance when mixer nozzles were applied to the core of a subscale turbofan engine. The primary concern of the mixer nozzle is how to satisfy both less jet mixing noise emission and minimum impact on engine performance parameters such as thrust and fuel consumption. A notched nozzle, a nozzle with tiny dents on the trailing edge, initiates small disturbances in the shear layer, weakens the shear stress, and suppresses jet noise. The Japan Aerospace Exploration Agency (JAXA) and IHI Corporation have studied notched nozzles and found that finer and more notches are preferable for both acoustic and aerodynamic performance.\u0000 As a next step, it is necessary to maintain the tradeoff between noise suppression and impact on engine performance. To evaluate both the acoustic and aerodynamic performance with the notched nozzle, a subscale turbofan engine, DGEN380, was adopted as a demonstration engine. Experiments with this engine were conducted both in a test cell and in an open test site. The notched nozzle, together with a baseline conical nozzle and a referential serrated nozzle, i.e., a chevron nozzle, was applied to the core exhaust of the engine.\u0000 The experiment in the test cell clarified that the notched nozzle possibly provides better thrust specific fuel consumption than the referential chevron nozzle. The acoustic measurement in the open environment confirmed that the notched nozzle has the noise suppression characteristics expected from previous test results. The perceived noise levels are attenuated by 1.5 dB, which is the same as or better than the referential mixer nozzle.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"37 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":"132481129","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}
Naval applications require various modes of operation from a combination of driving sources to different ship propulsion systems. Various gear configurations are available for these applications. The driver types and operating modes generate different requirements for the selected clutch design. In this paper the application of different types of clutches will be compared for their specific applications, advantages and disadvantages.
{"title":"A Comparison of Clutch Types for Naval Propulsion","authors":"J. Bos, J. Mangnus, N. Bellamy","doi":"10.1115/GT2018-77291","DOIUrl":"https://doi.org/10.1115/GT2018-77291","url":null,"abstract":"Naval applications require various modes of operation from a combination of driving sources to different ship propulsion systems. Various gear configurations are available for these applications. The driver types and operating modes generate different requirements for the selected clutch design. In this paper the application of different types of clutches will be compared for their specific applications, advantages and disadvantages.","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":"129290096","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 paper discusses the aerodynamic optimization of low-pressure axial fans using adjoint Computational Fluid Dynamics (CFD). In the first part, a typical CFD-based fan optimization problem is introduced. The focus is on the CFD model and potential objective functions. The adjoint system of equations and the adjoint boundary conditions for this optimization problem are derived in the second part. Moreover, the software implementation in the open source CFD code OpenFOAM v3.0.x is described. The existing OpenFOAM solver “adjointShapeOptimizationFoam” serves as the basis and is customized to the optimization of fans. The code solves both the primal and the adjoint incompressible Reynolds-averaged Navier-Stokes (RANS) equations from which a sensitivity map of the objective function with respect to the grid topology can be derived. The main extension of the existing code deals with the consideration of a rotating frame of reference leading to additional source terms in both the primal and the adjoint RANS equations. Moreover, the implementation of new boundary conditions is performed to handle the distinct objective functions. In the third part, the customized adjoint solver is applied to improve an existing baseline fan. Two adjoint simulations of the baseline fan are performed aiming at maximization of pressure and efficiency, respectively. The resulting surface sensitivities on the blade are used to modify the blade shape accordingly. Eventually, the performance of the two optimized fans is predicted by RANS to quantify the improvements. The first fan features a pressure rise which is 3.6 % higher as compared to the baseline fan. The second fan features an efficiency improvement of 0.1 percentage points as compared to the baseline fan. Hence, the functionality of the adjoint method is proven. A more substantial improvement would require further optimization loops with repeated adjoint simulations that, however, are not part of this paper.
{"title":"Aerodynamic Optimization of Axial Fans Using the Adjoint Method","authors":"K. Bamberger, T. Carolus","doi":"10.1115/GT2018-77027","DOIUrl":"https://doi.org/10.1115/GT2018-77027","url":null,"abstract":"This paper discusses the aerodynamic optimization of low-pressure axial fans using adjoint Computational Fluid Dynamics (CFD).\u0000 In the first part, a typical CFD-based fan optimization problem is introduced. The focus is on the CFD model and potential objective functions.\u0000 The adjoint system of equations and the adjoint boundary conditions for this optimization problem are derived in the second part. Moreover, the software implementation in the open source CFD code OpenFOAM v3.0.x is described. The existing OpenFOAM solver “adjointShapeOptimizationFoam” serves as the basis and is customized to the optimization of fans. The code solves both the primal and the adjoint incompressible Reynolds-averaged Navier-Stokes (RANS) equations from which a sensitivity map of the objective function with respect to the grid topology can be derived. The main extension of the existing code deals with the consideration of a rotating frame of reference leading to additional source terms in both the primal and the adjoint RANS equations. Moreover, the implementation of new boundary conditions is performed to handle the distinct objective functions.\u0000 In the third part, the customized adjoint solver is applied to improve an existing baseline fan. Two adjoint simulations of the baseline fan are performed aiming at maximization of pressure and efficiency, respectively. The resulting surface sensitivities on the blade are used to modify the blade shape accordingly. Eventually, the performance of the two optimized fans is predicted by RANS to quantify the improvements. The first fan features a pressure rise which is 3.6 % higher as compared to the baseline fan. The second fan features an efficiency improvement of 0.1 percentage points as compared to the baseline fan. Hence, the functionality of the adjoint method is proven. A more substantial improvement would require further optimization loops with repeated adjoint simulations that, however, are not part of this paper.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"210 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":"131618828","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}
S. Reitenbach, A. Krumme, T. Behrendt, M. Schnös, T. Schmidt, S. Hönig, R. Mischke, E. Moerland
Central targets for jet engine research activities comprise the evaluation of improved engine components and the assessment of novel engine concepts for enhanced overall engine performance in order to reduce the fuel consumption and emissions of future aircraft. Since CO2 emissions are directly related to engine fuel burn, a reduction in fuel consumption leads to lower CO2 emissions. Therefore improvements in engine technologies are still significant and a multi-disciplinary pre-design approach is essential in order to address all requirements and constraints associated with different engine concepts. Furthermore, an increase in effectiveness of the preliminary design process helps reduce the immense costs of the overall engine development. Within the DLR project PEGASUS (Preliminary Gas Turbine Assessment and Sizing) a multi-disciplinary pre-design and assessment competence of the DLR regarding aero engines and gas turbines was established. The application of modern preliminary design methods allows for the construction and evaluation of innovative next generation engine concepts. The purpose of this paper is to present the developed multi-disciplinary pre-design process and its application to three aero engine models. First, a state of the art twin spool mixed flow turbofan engine model is created for validation purposes. The second and third engine models investigated comprise future engine concepts: a Counter Rotating Open Rotor and an Ultra High Bypass Turbofan. The turbofan used for validation is based on publicly available reference data from manufacturing and emission certification. At first the identified interfaces and constraints of the entire pre-design process are presented. An important factor of complexity in this highly iterative procedure is the intricate data flow, as well as the extensive amount of data transferred between all involved disciplines and among the different fidelity levels applied within the smoothly connected design phases. To cope with the inherent complexity data modeling techniques have been applied to explicitly determine the required data structures of those complex systems. The resulting data model characterizing the components of a gas turbine and their relationships in the design process is presented in detail. Based on the established data model the entire engine pre-design process is presented. Starting with the definition of a flight mission scenario and the resulting top level engine requirements thermodynamic engine performance models are developed. By means of these thermodynamic models, a detailed engine component pre-design is conducted. The aerodynamic and structural design of the engine components are executed using a stepwise increase in level of detail and are continuously evaluated in the context of the overall engine system.
{"title":"Design and Application of a Multi-Disciplinary Pre-Design Process for Novel Engine Concepts","authors":"S. Reitenbach, A. Krumme, T. Behrendt, M. Schnös, T. Schmidt, S. Hönig, R. Mischke, E. Moerland","doi":"10.1115/gt2018-76880","DOIUrl":"https://doi.org/10.1115/gt2018-76880","url":null,"abstract":"Central targets for jet engine research activities comprise the evaluation of improved engine components and the assessment of novel engine concepts for enhanced overall engine performance in order to reduce the fuel consumption and emissions of future aircraft. Since CO2 emissions are directly related to engine fuel burn, a reduction in fuel consumption leads to lower CO2 emissions. Therefore improvements in engine technologies are still significant and a multi-disciplinary pre-design approach is essential in order to address all requirements and constraints associated with different engine concepts. Furthermore, an increase in effectiveness of the preliminary design process helps reduce the immense costs of the overall engine development.\u0000 Within the DLR project PEGASUS (Preliminary Gas Turbine Assessment and Sizing) a multi-disciplinary pre-design and assessment competence of the DLR regarding aero engines and gas turbines was established. The application of modern preliminary design methods allows for the construction and evaluation of innovative next generation engine concepts.\u0000 The purpose of this paper is to present the developed multi-disciplinary pre-design process and its application to three aero engine models. First, a state of the art twin spool mixed flow turbofan engine model is created for validation purposes. The second and third engine models investigated comprise future engine concepts: a Counter Rotating Open Rotor and an Ultra High Bypass Turbofan. The turbofan used for validation is based on publicly available reference data from manufacturing and emission certification.\u0000 At first the identified interfaces and constraints of the entire pre-design process are presented. An important factor of complexity in this highly iterative procedure is the intricate data flow, as well as the extensive amount of data transferred between all involved disciplines and among the different fidelity levels applied within the smoothly connected design phases. To cope with the inherent complexity data modeling techniques have been applied to explicitly determine the required data structures of those complex systems. The resulting data model characterizing the components of a gas turbine and their relationships in the design process is presented in detail.\u0000 Based on the established data model the entire engine pre-design process is presented. Starting with the definition of a flight mission scenario and the resulting top level engine requirements thermodynamic engine performance models are developed. By means of these thermodynamic models, a detailed engine component pre-design is conducted. The aerodynamic and structural design of the engine components are executed using a stepwise increase in level of detail and are continuously evaluated in the context of the overall engine system.","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":"131759523","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}
Zhitao Wang, Liang Jian, Li Tielei, Wang Weitian, Shuying Li
The combined diesel-electric and gas turbine (CODLAG) plant is a new type of ship power plant combining the advantages of electric propulsion system and mechanical propulsion system. The requires about ship power grid is lower than full electric propulsion mode, at the same time it can gain the quiet of electric propulsion in the low working conditions and increase the mobility of the ship in the high working conditions. Unlike traditional mechanical propulsion methods and forward-looking all-electric propulsion methods, the CODLAG plant has a coupling between mechanical propulsion and electric propulsion mode. The cooperative working characteristics of two different nature systems is still need further research. For the in-depth research of CODLAG device’s characters, this study built a simulation model of CODLAG device based on Matlab/Simulink and C/C++ platform. A kind of torque-shaft speed double closed-loop control strategy based on PID was used on the CODLAG device. And the typical work condition of CODLAG, including merging, merging off and variable work condition, was simulated in this study. Through the simulation, the dynamic response of main parameters at typical condition have been got. Then, characters of CODLAG device with CPP was simulated at variable condition. And the thrust response was compared with FPP’s. Through comparative analysis, the effectiveness of integrated simulation method specifying to CODLAG device was verified, and some useful conference was provided for the future research.
{"title":"Simulation Study on the Work Characteristics of Combined Diesel-Electric and Gas Turbine (CODLAG)","authors":"Zhitao Wang, Liang Jian, Li Tielei, Wang Weitian, Shuying Li","doi":"10.1115/GT2018-76029","DOIUrl":"https://doi.org/10.1115/GT2018-76029","url":null,"abstract":"The combined diesel-electric and gas turbine (CODLAG) plant is a new type of ship power plant combining the advantages of electric propulsion system and mechanical propulsion system. The requires about ship power grid is lower than full electric propulsion mode, at the same time it can gain the quiet of electric propulsion in the low working conditions and increase the mobility of the ship in the high working conditions. Unlike traditional mechanical propulsion methods and forward-looking all-electric propulsion methods, the CODLAG plant has a coupling between mechanical propulsion and electric propulsion mode. The cooperative working characteristics of two different nature systems is still need further research.\u0000 For the in-depth research of CODLAG device’s characters, this study built a simulation model of CODLAG device based on Matlab/Simulink and C/C++ platform. A kind of torque-shaft speed double closed-loop control strategy based on PID was used on the CODLAG device. And the typical work condition of CODLAG, including merging, merging off and variable work condition, was simulated in this study.\u0000 Through the simulation, the dynamic response of main parameters at typical condition have been got. Then, characters of CODLAG device with CPP was simulated at variable condition. And the thrust response was compared with FPP’s. Through comparative analysis, the effectiveness of integrated simulation method specifying to CODLAG device was verified, and some useful conference was provided for the future research.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"18 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":"121640980","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. Pokhrel, Jonathan C. Gladin, Elena Garcia, D. Mavris
Efforts to achieve NASA’s N+2 and N+3 fuel burn goals have led to various future aircraft concepts. A commonality in all these concepts is the presence of a high degree of interaction among the various disciplines involved. A tightly integrated propulsion/airframe results in distortion in the flow field around the engine annulus. Although beneficial in terms of propulsive efficiency (due to boundary layer ingestion), the impact of distortion on fan performance and operability remains in question for these concepts. As such, rapid evaluation of the impacts of distortion during the conceptual design phase is necessary to assess various concepts. This is especially important given the expansion of the design space afforded by turbo-electric and hybrid-electric distributed propulsion concepts, in which the gas turbine generator and propulsive devices can be decoupled in space. A simple and rapid methodology to assess operability of compressors is the theory of Parallel Compressors (PC). PC theory views the compressor as two compressors in parallel, one with a uniform high Pt and the other with a uniform low Pt, both operating at the same speed and exiting to a common static pressure. The assumption of two compressors exiting at the common static pressure is not entirely true, especially when the distortion is high. In this paper, the development of a modified parallel compressor model with parametric boundary condition that can capture the impact of non-uniform inflow on fan performance is introduced and validated. Unlike classical PC model, the modified approach introduces a boundary condition dependent on the intensity of distortion (DPCP) at the Aerodynamic Interface Plane (AIP). Additionally, the concept of PC is also extended to Multi-Per Revolution (MPR) distortion. A modeling environment which follows this methodology is created in PROOSIS, an object oriented 0-D cycle code. The model was created using the “compressor” components acting in parallel and a procedure for implementing both design mode and off-design mode solutions was created using the PROOSIS toolset. The example problem was implemented to demonstrate two capabilities — i) the ability of quantifying impacts on thrust and performance of a ducted fan propulsion system, and ii) the ability of predicting loss in stability pressure ratio. The results clearly show the ability of the tool to quantify distortion related losses. The work described in this paper can be integrated to a Multi-Disciplinary Design and Optimization (MDAO) framework along with other disciplines and can be used to evaluate the viability of design space offered by novel aircraft configurations.
{"title":"A Methodology for Quantifying Distortion Impacts Using a Modified Parallel Compressor Theory","authors":"M. Pokhrel, Jonathan C. Gladin, Elena Garcia, D. Mavris","doi":"10.1115/GT2018-77089","DOIUrl":"https://doi.org/10.1115/GT2018-77089","url":null,"abstract":"Efforts to achieve NASA’s N+2 and N+3 fuel burn goals have led to various future aircraft concepts. A commonality in all these concepts is the presence of a high degree of interaction among the various disciplines involved. A tightly integrated propulsion/airframe results in distortion in the flow field around the engine annulus. Although beneficial in terms of propulsive efficiency (due to boundary layer ingestion), the impact of distortion on fan performance and operability remains in question for these concepts. As such, rapid evaluation of the impacts of distortion during the conceptual design phase is necessary to assess various concepts. This is especially important given the expansion of the design space afforded by turbo-electric and hybrid-electric distributed propulsion concepts, in which the gas turbine generator and propulsive devices can be decoupled in space.\u0000 A simple and rapid methodology to assess operability of compressors is the theory of Parallel Compressors (PC). PC theory views the compressor as two compressors in parallel, one with a uniform high Pt and the other with a uniform low Pt, both operating at the same speed and exiting to a common static pressure. The assumption of two compressors exiting at the common static pressure is not entirely true, especially when the distortion is high. In this paper, the development of a modified parallel compressor model with parametric boundary condition that can capture the impact of non-uniform inflow on fan performance is introduced and validated. Unlike classical PC model, the modified approach introduces a boundary condition dependent on the intensity of distortion (DPCP) at the Aerodynamic Interface Plane (AIP). Additionally, the concept of PC is also extended to Multi-Per Revolution (MPR) distortion.\u0000 A modeling environment which follows this methodology is created in PROOSIS, an object oriented 0-D cycle code. The model was created using the “compressor” components acting in parallel and a procedure for implementing both design mode and off-design mode solutions was created using the PROOSIS toolset. The example problem was implemented to demonstrate two capabilities — i) the ability of quantifying impacts on thrust and performance of a ducted fan propulsion system, and ii) the ability of predicting loss in stability pressure ratio. The results clearly show the ability of the tool to quantify distortion related losses.\u0000 The work described in this paper can be integrated to a Multi-Disciplinary Design and Optimization (MDAO) framework along with other disciplines and can be used to evaluate the viability of design space offered by novel aircraft configurations.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"401 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":"116503339","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}
Centrifugal blowers are widely used in automotive, heating, ventilating, air-conditioning and other industrial purposes. In fact, they allow high-pressure increase to a moderately high mass flow rate, despite the reduced overall dimensions of the system. Numerous authors have worked to increase the fluid dynamic efficiency of the impeller and the volute. However, the recent sound emission standards have imposed tighter constraints, making the noise reduction one of the most challenging target for the design. The reduction of the tonal noise is the main concern for these blowers because the noise at the first harmonic is clearly distinguishable in the noise spectrum. Techniques to reduce this peak generally rely on experimental measurements in aeroacoustics laboratory. In this work, a CFD procedure has been developed to accurately predict the tonal noise in radial bowers. The approach has been validated using real geometries and experimental data. Various turbulence models have been tested to find the best results without the use of excessive computational resources. Moreover, unsteady simulations of the 3D blower have been carried out to analyze the influence of the main geometric parameters on the tonal noise reduction. A parametric design code developed by the authors have been used to change the geometry in order to identify the effect of the main geometrical design parameters on both fluid dynamic and aeroacoustics performance.
{"title":"Numerical Prediction of Tonal Noise in Centrifugal Blowers","authors":"C. Cravero, D. Marsano","doi":"10.1115/GT2018-75243","DOIUrl":"https://doi.org/10.1115/GT2018-75243","url":null,"abstract":"Centrifugal blowers are widely used in automotive, heating, ventilating, air-conditioning and other industrial purposes. In fact, they allow high-pressure increase to a moderately high mass flow rate, despite the reduced overall dimensions of the system. Numerous authors have worked to increase the fluid dynamic efficiency of the impeller and the volute. However, the recent sound emission standards have imposed tighter constraints, making the noise reduction one of the most challenging target for the design. The reduction of the tonal noise is the main concern for these blowers because the noise at the first harmonic is clearly distinguishable in the noise spectrum. Techniques to reduce this peak generally rely on experimental measurements in aeroacoustics laboratory. In this work, a CFD procedure has been developed to accurately predict the tonal noise in radial bowers. The approach has been validated using real geometries and experimental data. Various turbulence models have been tested to find the best results without the use of excessive computational resources. Moreover, unsteady simulations of the 3D blower have been carried out to analyze the influence of the main geometric parameters on the tonal noise reduction. A parametric design code developed by the authors have been used to change the geometry in order to identify the effect of the main geometrical design parameters on both fluid dynamic and aeroacoustics performance.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"25 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":"133886684","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}
Recent inspection of shipboard gas-turbine components under the platform has indicated the apparent presence of CMAS (calcium, magnesium, alumino-silicate) and its related attack. This type of attack has often been observed in aero gas turbine engines when sand and similar siliceous matter is ingested into the engine and the sand debris melts due to high engine operating temperature greater than 1150°C. Initial chemical analysis shows that the CMAS-affected areas of ship engine components versus aero engine components are similar. However, this phenomenon commonly observed in advanced aeroengines are not supposed to occur in the ship engine components since their probable temperature is known to be much lower than 1150°C (i.e., melting temperature of CMAS). As a consequence, some important questions arise as to: What caused this “CMAS” attack in ship engine components? Was this initiated by hot corrosion, which created a molten salt pool at a sufficient temperature to trigger CMAS attack? Did sodium chloride mixed with dust and debris lower the temperature at which molten CMAS would initiate? Past research provides a basic understanding of hot corrosion, but may ignore other reactants and other species inherently associated with ‘natural CMAS’ and mechanisms contributing to hot corrosion or CMAS attack. Further examination of ship and aero components will discern the local structure chemical profile of the component coatings, the chemical compositions of the alloy substrates, and the interface between the coating and the molten “CMAS” by several methods. Integrated computational materials engineering (ICME) and validating experiments will assist in developing degradation mechanisms. The environment complexity is also to be taken into account to determine whether salt-induced CMAS attack or CaO-induced hot corrosion may be dominant. The mechanisms need to be further studied and defined. The current work will address a series of systematic approaches to the aforementioned CMAS issues and will also present some recent results on CMAS-related effects on components and an elected alloy material system.
{"title":"CMAS Effects on Ship Gas-Turbine Components/Materials","authors":"D. Shifler, S. R. Choi","doi":"10.1115/GT2018-75865","DOIUrl":"https://doi.org/10.1115/GT2018-75865","url":null,"abstract":"Recent inspection of shipboard gas-turbine components under the platform has indicated the apparent presence of CMAS (calcium, magnesium, alumino-silicate) and its related attack. This type of attack has often been observed in aero gas turbine engines when sand and similar siliceous matter is ingested into the engine and the sand debris melts due to high engine operating temperature greater than 1150°C. Initial chemical analysis shows that the CMAS-affected areas of ship engine components versus aero engine components are similar. However, this phenomenon commonly observed in advanced aeroengines are not supposed to occur in the ship engine components since their probable temperature is known to be much lower than 1150°C (i.e., melting temperature of CMAS). As a consequence, some important questions arise as to: What caused this “CMAS” attack in ship engine components? Was this initiated by hot corrosion, which created a molten salt pool at a sufficient temperature to trigger CMAS attack? Did sodium chloride mixed with dust and debris lower the temperature at which molten CMAS would initiate?\u0000 Past research provides a basic understanding of hot corrosion, but may ignore other reactants and other species inherently associated with ‘natural CMAS’ and mechanisms contributing to hot corrosion or CMAS attack. Further examination of ship and aero components will discern the local structure chemical profile of the component coatings, the chemical compositions of the alloy substrates, and the interface between the coating and the molten “CMAS” by several methods. Integrated computational materials engineering (ICME) and validating experiments will assist in developing degradation mechanisms.\u0000 The environment complexity is also to be taken into account to determine whether salt-induced CMAS attack or CaO-induced hot corrosion may be dominant. The mechanisms need to be further studied and defined. The current work will address a series of systematic approaches to the aforementioned CMAS issues and will also present some recent results on CMAS-related effects on components and an elected alloy material system.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"15 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":"133163134","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}
Axial fans are widely used in modern industry and new regulations and stringent environmental concerns are prompting manufacturer to design efficient low-noise axial fans. This paper is focused on improving the aerodynamic performances and reducing the tonal noise at BPF and its harmonics by the optimum choice of lean-swept blade and the stacking line for the low-speed axial fan. The aerodynamic characteristics of the axial fan with a shroud are explored by CFD with ANASYS CFX. A hybrid method, SST turbulence model for flow and FW-H equation for acoustics, is chosen to predict the radiated noise. The accuracy and reliability of predicted aerodynamic and aeroacoustics results are verified by comparing both computation and experimental data. A number of modified blades with different leaned angle, swept angle and the stacking lines are modeled and analyzed, and the investigation into the optimum choice of lean-swept blade and the stacking line is conducted according to aerodynamic performances and tonal noise. Q-criterion which can visualize the major flow disturbances is applied for the purpose of identification of acoustic sources. The turbulent flow structures on the leading edge, tip and suction side of the blade are main noise sources. An optimal modification is determined through the analysis of the aerodynamic performances and noise, which is to achieve the desired performances by blade sweep and lean and adjusting the stacking line. The results show that aerodynamic and acoustic performances of the optimized fan are better than that of the original fan and the improvement is more obvious to change the stacking line with centre of gravity compare to blade sweep and lean for the low-speed axial fan.
{"title":"Aerodynamic Characteristics and Noise Analysis of a Low-Speed Axial Fan","authors":"B. Luo, W. Chu, W. Dong, Xiangyi Chen","doi":"10.1115/GT2018-76079","DOIUrl":"https://doi.org/10.1115/GT2018-76079","url":null,"abstract":"Axial fans are widely used in modern industry and new regulations and stringent environmental concerns are prompting manufacturer to design efficient low-noise axial fans. This paper is focused on improving the aerodynamic performances and reducing the tonal noise at BPF and its harmonics by the optimum choice of lean-swept blade and the stacking line for the low-speed axial fan. The aerodynamic characteristics of the axial fan with a shroud are explored by CFD with ANASYS CFX. A hybrid method, SST turbulence model for flow and FW-H equation for acoustics, is chosen to predict the radiated noise. The accuracy and reliability of predicted aerodynamic and aeroacoustics results are verified by comparing both computation and experimental data. A number of modified blades with different leaned angle, swept angle and the stacking lines are modeled and analyzed, and the investigation into the optimum choice of lean-swept blade and the stacking line is conducted according to aerodynamic performances and tonal noise. Q-criterion which can visualize the major flow disturbances is applied for the purpose of identification of acoustic sources. The turbulent flow structures on the leading edge, tip and suction side of the blade are main noise sources. An optimal modification is determined through the analysis of the aerodynamic performances and noise, which is to achieve the desired performances by blade sweep and lean and adjusting the stacking line. The results show that aerodynamic and acoustic performances of the optimized fan are better than that of the original fan and the improvement is more obvious to change the stacking line with centre of gravity compare to blade sweep and lean for the low-speed axial fan.","PeriodicalId":114672,"journal":{"name":"Volume 1: Aircraft Engine; Fans and Blowers; Marine","volume":"5 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":"124025575","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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