Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-4613
S. Wiesche, Felix Reinker, R. Wagner, P. Epple, M. Fritsche, Hans J. Rußwurm
A novel thermal measurement approach is presented for the determination of fan efficiencies. This approach is not resting on a simple direct measurement of the occurring temperature difference but on a system identification based on the transient time signal of the involved temperature measurement device. The values of the system parameters can be identified after recording the transient response of the system to a step input, i. e. the fan is suddenly turned on. By means of a representative case study considering a centrifugal fan, the system identification and its relation to fan efficiency are presented. The outcome of the new thermal approach is compared with results of standardized fan performance tests and with results obtained by the direct temperature measurement method without system identification. It is shown that the direct temperature measurement provides typically poor data whereas the novel thermal approach leads to results which are well comparable with these obtained by standard performance test at the design point.
{"title":"An Accurate Thermal Measurement Approach for Determining Fan Efficiencies Based on System Identification","authors":"S. Wiesche, Felix Reinker, R. Wagner, P. Epple, M. Fritsche, Hans J. Rußwurm","doi":"10.1115/ajkfluids2019-4613","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4613","url":null,"abstract":"\u0000 A novel thermal measurement approach is presented for the determination of fan efficiencies. This approach is not resting on a simple direct measurement of the occurring temperature difference but on a system identification based on the transient time signal of the involved temperature measurement device. The values of the system parameters can be identified after recording the transient response of the system to a step input, i. e. the fan is suddenly turned on. By means of a representative case study considering a centrifugal fan, the system identification and its relation to fan efficiency are presented. The outcome of the new thermal approach is compared with results of standardized fan performance tests and with results obtained by the direct temperature measurement method without system identification. It is shown that the direct temperature measurement provides typically poor data whereas the novel thermal approach leads to results which are well comparable with these obtained by standard performance test at the design point.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121046471","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}
Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-4607
K. Anderson, C. Méndez
The numerical modeling of the premixed combustion occurring in the chamber of a polygon engine is presented in this paper. This research is being carried out to support the analysis and design of a lightweight, two-stroke, six-sided, in-plane, polygon engine. Results for average combustion chamber temperature, turbulent flame speed, progress variable, and Damkohler number versus piston position are presented for methane (CH4), diesel (C10H22), and ethanol (C2H50H) fuels, respectively.
{"title":"CFD Analysis of Premixed Combustion in a Two Stroke Polygon Engine","authors":"K. Anderson, C. Méndez","doi":"10.1115/ajkfluids2019-4607","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4607","url":null,"abstract":"\u0000 The numerical modeling of the premixed combustion occurring in the chamber of a polygon engine is presented in this paper. This research is being carried out to support the analysis and design of a lightweight, two-stroke, six-sided, in-plane, polygon engine. Results for average combustion chamber temperature, turbulent flame speed, progress variable, and Damkohler number versus piston position are presented for methane (CH4), diesel (C10H22), and ethanol (C2H50H) fuels, respectively.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125178895","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}
Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-4744
K. Anderson, Andrew Murphy
In this study 3-D CFD modeling of a cylindrical stack Proton-exchange membrane fuel cell (PEMFC) is provided. The H2O-O2 PEMFC uses a 10.8 mm2 area membrane and Platinum (Pt) catalyst. The paper presents the methodology for the PEMFC commercial software module, the set-up of the Computational Fluid Dynamics (CFD) geometry, mesh and boundary conditions. Results for the current-voltage performance curves and 3-D contour plots of the fluid, heat and species concentrations within the PEMFC are given. Results are presented for a low-temperature fuel cell using NAFION membrane and a high-temperature fuel cell using BZY membrane.
{"title":"CFD Investigation of a PEMFC Stack Assembly","authors":"K. Anderson, Andrew Murphy","doi":"10.1115/ajkfluids2019-4744","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4744","url":null,"abstract":"\u0000 In this study 3-D CFD modeling of a cylindrical stack Proton-exchange membrane fuel cell (PEMFC) is provided. The H2O-O2 PEMFC uses a 10.8 mm2 area membrane and Platinum (Pt) catalyst. The paper presents the methodology for the PEMFC commercial software module, the set-up of the Computational Fluid Dynamics (CFD) geometry, mesh and boundary conditions. Results for the current-voltage performance curves and 3-D contour plots of the fluid, heat and species concentrations within the PEMFC are given. Results are presented for a low-temperature fuel cell using NAFION membrane and a high-temperature fuel cell using BZY membrane.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122930527","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}
Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-4860
Youn-Sung Kim, Hyeon-Seok Shim, Kwang‐Yong Kim
This paper presents a study of the effects of blade pitch angle and inlet guide vane (IGV) angle on the performance of a submersible axial-flow pump. To analyze the interaction effects between the IGVs and the rotor blades, both steady and unsteady three-dimensional Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model were solved. Hexahedral meshes were used in the computational domain and a grid-dependency test was performed to obtain an optimal number of grid nodes. The performance curves obtained by numerical simulation showed good agreement with experimental data. The results show that the fluctuation of hydraulic efficiency and head coefficient increased significantly under overload conditions as the IGV setting angle increased. Additionally, both the steady and unsteady performance characteristics were shown to be quite dependent on the combination of IGV angle and blade pitch angle, because the relative velocity at leading edge played an important role in the performance under overload conditions.
{"title":"Investigation of Unsteady Performance Characteristics of a Submersible Axial-Flow Pump for Different IGV and Blade Pitch Angles","authors":"Youn-Sung Kim, Hyeon-Seok Shim, Kwang‐Yong Kim","doi":"10.1115/ajkfluids2019-4860","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4860","url":null,"abstract":"\u0000 This paper presents a study of the effects of blade pitch angle and inlet guide vane (IGV) angle on the performance of a submersible axial-flow pump. To analyze the interaction effects between the IGVs and the rotor blades, both steady and unsteady three-dimensional Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model were solved. Hexahedral meshes were used in the computational domain and a grid-dependency test was performed to obtain an optimal number of grid nodes. The performance curves obtained by numerical simulation showed good agreement with experimental data. The results show that the fluctuation of hydraulic efficiency and head coefficient increased significantly under overload conditions as the IGV setting angle increased. Additionally, both the steady and unsteady performance characteristics were shown to be quite dependent on the combination of IGV angle and blade pitch angle, because the relative velocity at leading edge played an important role in the performance under overload conditions.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125742007","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}
Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-4801
Ill-yeong Lee, I. Iwan, Sae-ryung Choi, J. Huh
The control performance of hydraulic systems is basically influenced by the performance of electro-hydraulic servo valve used in a hydraulic control system. In this study, the authors propose a control design to improve the control performance of servo valves with a non-contact eddy current type displacement sensor. Mathematical model for the valve is obtained through an experimental identification process. A PI-D controller together with a feedforward (FF) controller is applied to the valve. To further improve the response of the servo valve, an input shaping filter (ISF) is incorporated into the valve control system. Finally, the effectiveness of the proposed control system is verified experimentally.
{"title":"Performance Improvement of Electro-Hydraulic Servo Valve Using a Feed-Forward Control and an Input Shaping Filter","authors":"Ill-yeong Lee, I. Iwan, Sae-ryung Choi, J. Huh","doi":"10.1115/ajkfluids2019-4801","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4801","url":null,"abstract":"\u0000 The control performance of hydraulic systems is basically influenced by the performance of electro-hydraulic servo valve used in a hydraulic control system. In this study, the authors propose a control design to improve the control performance of servo valves with a non-contact eddy current type displacement sensor. Mathematical model for the valve is obtained through an experimental identification process. A PI-D controller together with a feedforward (FF) controller is applied to the valve. To further improve the response of the servo valve, an input shaping filter (ISF) is incorporated into the valve control system. Finally, the effectiveness of the proposed control system is verified experimentally.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133328013","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}
Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-5106
M. Steppert, P. Epple, Michael Steber, Michael Florschuetz, Felix Schneider, Kevin Habrock, Erwin Ruppelt, Sebastian Eideloth, Anja Seitz
In this work a new exhaust air system for rotary screw compressors with integrated refrigeration dryers has been developed. The new system unites both, the exhaust air flow out of the compressor and out of the refrigeration drier and in such a way the overall exhaust air and hence the overall heat are exhausted through one single air duct. For the development of the system, the ASD 50 T SFC compressor system from KAESER Kompressoren SE [1] was used. Because of the slight overpressure in the exhaust air duct due to the cooling radial fan in the compressor, a jet pump was designed and placed into the main exhaust air duct to reduce the static pressure in the main duct. In such a way, after the jet pump the exhaust air of the refrigeration drier is sucked into the main exhaust air duct through an intake fitting. The nozzle and the intake fitting of the exhaust air duct were first designed by using the commercial CFD solver CFX from ANSYS. The nozzle length, angle and diameter were varied to determine the best geometry. In order to validate the components designed by CFD simulations, three of the designs were manufactured and measured in the compressor laboratory at Coburg University. Therefor heat and velocity measurements in the exhaust air ducts have been done. Also the flow of the exhaust air was visualized using smoke and laser sheets. The simulation and experimental results are shown in detail in this work.
本文研制了一种新的螺杆压缩机综合制冷干燥机排风系统。新系统将两者结合起来，从压缩机和制冷干燥机中排出的废气以这种方式排出的空气和热量通过一个单一的风管排出。在系统的开发中，采用了KAESER Kompressoren SE[1]的ASD 50 T SFC压缩机系统。针对压气机内冷却径向风扇在排风道内产生的轻微超压问题，设计并在主排风道内放置喷射泵，以降低主风道内的静压。这样，在喷射泵之后，制冷干燥机的排风通过进气配件被吸入主排风道。首先利用ANSYS的商用CFD求解器CFX对喷管和排风道进气配件进行了设计。通过改变喷嘴的长度、角度和直径来确定最佳形状。为了验证CFD模拟设计的部件，在科堡大学的压缩机实验室制造并测量了其中的三个设计。因此，对排风管中的热和速度进行了测量。此外，废气的流动是可视化使用烟雾和激光片。文中给出了详细的仿真和实验结果。
{"title":"Development of a New Exhaust Air System for Combined Air Compressor and Dryer System","authors":"M. Steppert, P. Epple, Michael Steber, Michael Florschuetz, Felix Schneider, Kevin Habrock, Erwin Ruppelt, Sebastian Eideloth, Anja Seitz","doi":"10.1115/ajkfluids2019-5106","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5106","url":null,"abstract":"\u0000 In this work a new exhaust air system for rotary screw compressors with integrated refrigeration dryers has been developed. The new system unites both, the exhaust air flow out of the compressor and out of the refrigeration drier and in such a way the overall exhaust air and hence the overall heat are exhausted through one single air duct. For the development of the system, the ASD 50 T SFC compressor system from KAESER Kompressoren SE [1] was used. Because of the slight overpressure in the exhaust air duct due to the cooling radial fan in the compressor, a jet pump was designed and placed into the main exhaust air duct to reduce the static pressure in the main duct. In such a way, after the jet pump the exhaust air of the refrigeration drier is sucked into the main exhaust air duct through an intake fitting. The nozzle and the intake fitting of the exhaust air duct were first designed by using the commercial CFD solver CFX from ANSYS. The nozzle length, angle and diameter were varied to determine the best geometry. In order to validate the components designed by CFD simulations, three of the designs were manufactured and measured in the compressor laboratory at Coburg University. Therefor heat and velocity measurements in the exhaust air ducts have been done. Also the flow of the exhaust air was visualized using smoke and laser sheets. The simulation and experimental results are shown in detail in this work.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129156452","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}
Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-5001
Takanori Matsui, T. Fukui, K. Morinishi
The output power coefficient of the Savonius rotor should be improved for better practical applications. So far, new Savonius rotor has been developed to improve the minimum output coefficient by adding semi-elliptical blade. Thus, the purpose of this research is to investigate the influence of the additional semi-elliptical blade’s position on the output coefficient. Flow around the rotor was simulated by using the regularized lattice Boltzmann method. The virtual flux method was used to express the shape of the rotor on a Cartesian grid, and the multi-block method was used for local fine grids of the rotor. The rotation speed of the Savonius rotor was maintained constant, and its performance was evaluated by the output power and torque coefficients. As a result, the semi-elliptical blade successfully generated additional positive torque in the range of the advancing phase and improved the minimum output power coefficient of the rotor during a cycle. When the moment arm is short, the semi-elliptical blade did not generate large negative torque in the range of the returning phase owing to its position behind the main blade in the wind flow direction. The output power coefficient of the new Savonius rotor was improved compared to that of the traditional one depending on the length of the semi-elliptical blade’s moment arm.
{"title":"Computational Fluid Dynamics to Assess the Blade Effect of a New Savonius Rotor for Improvement of the Output Power Coefficient","authors":"Takanori Matsui, T. Fukui, K. Morinishi","doi":"10.1115/ajkfluids2019-5001","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5001","url":null,"abstract":"\u0000 The output power coefficient of the Savonius rotor should be improved for better practical applications. So far, new Savonius rotor has been developed to improve the minimum output coefficient by adding semi-elliptical blade. Thus, the purpose of this research is to investigate the influence of the additional semi-elliptical blade’s position on the output coefficient. Flow around the rotor was simulated by using the regularized lattice Boltzmann method. The virtual flux method was used to express the shape of the rotor on a Cartesian grid, and the multi-block method was used for local fine grids of the rotor. The rotation speed of the Savonius rotor was maintained constant, and its performance was evaluated by the output power and torque coefficients. As a result, the semi-elliptical blade successfully generated additional positive torque in the range of the advancing phase and improved the minimum output power coefficient of the rotor during a cycle. When the moment arm is short, the semi-elliptical blade did not generate large negative torque in the range of the returning phase owing to its position behind the main blade in the wind flow direction. The output power coefficient of the new Savonius rotor was improved compared to that of the traditional one depending on the length of the semi-elliptical blade’s moment arm.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126511649","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}
Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-5253
Jun Ikeda, Javier Sanchez Rios, N. Kuratani, Ken Ogawa, M. Tsubokura
In this study, unsteady flow simulations using a large-eddy simulation are conducted to analyze vehicle aerodynamics. The objective is to investigate flow structures that cause unsteady lift fluctuations potentially affecting the drivability of a vehicle. In addition, the dependence on the yaw angle of the incoming flow yaw angle is studied. The target model is a sedan-type vehicle that includes a complex underbody geometry and engine compartment. The model is based on production CAD drawings. The yaw angle of the incoming flow is set to 0°, 3°, and 5°. The simulation results are analyzed by several post-processing methods, such as root-mean-square of the transient pressure field, power spectral density of the lift force, and dynamic mode decomposition method to extract the flow features associated with the unsteady lift fluctuation. It is concluded that the aerodynamic fluctuation that may affect a vehicle’s vertical stability is concentrated on the rear tire and bumper area. In addition, when the yaw angle of the incoming flow increases, the fluctuation of the lift and the disturbance of flow structures are enhanced.
{"title":"Numerical Investigation of Fluctuating Aerodynamic Lift Acting on the Road Vehicle Which Affects Drivability","authors":"Jun Ikeda, Javier Sanchez Rios, N. Kuratani, Ken Ogawa, M. Tsubokura","doi":"10.1115/ajkfluids2019-5253","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5253","url":null,"abstract":"\u0000 In this study, unsteady flow simulations using a large-eddy simulation are conducted to analyze vehicle aerodynamics. The objective is to investigate flow structures that cause unsteady lift fluctuations potentially affecting the drivability of a vehicle. In addition, the dependence on the yaw angle of the incoming flow yaw angle is studied. The target model is a sedan-type vehicle that includes a complex underbody geometry and engine compartment. The model is based on production CAD drawings. The yaw angle of the incoming flow is set to 0°, 3°, and 5°. The simulation results are analyzed by several post-processing methods, such as root-mean-square of the transient pressure field, power spectral density of the lift force, and dynamic mode decomposition method to extract the flow features associated with the unsteady lift fluctuation. It is concluded that the aerodynamic fluctuation that may affect a vehicle’s vertical stability is concentrated on the rear tire and bumper area. In addition, when the yaw angle of the incoming flow increases, the fluctuation of the lift and the disturbance of flow structures are enhanced.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122319330","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}
Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-5220
Ang Li, Jun Chen, Yangfan Liu, J. Bolton, P. Davies
In recent years, the bladeless fan that does not have visible impellers have been widely applied in household appliances. Since the customers are particularly sensitive to noise and the strength of wind generated by the fan, the aerodynamic and acoustic performances of the fan need to be accurately characterized in the design stage. In this study, computational fluid dynamic (CFD) and computational aeroacoustics (CAA) are applied to investigate the performances of different designs of a bladeless fan model. The influence of four parameters, namely the airfoil selection for cross-section of the wind channel, the slit width, the height of cross-section and the location of the slit, is investigated. The results indicate the streamwise air velocity increases significantly by narrowing the outlet, but the noise level increases simultaneously. In addition, the generated noise increases while the height of fan cross-section increases, and a 4mm height of the cross section is optimal for aerodynamic performance. When the slit is closer to the location of maximum thickness, the performances of the bladeless fan increases. Moreover, the performance is not changed significantly by changing the cross-sectional profile. Finally, the optimal geometric parameters are identified to guide the future design of the bladeless fan.
{"title":"Influence of Geometric Parameters on Aerodynamic and Acoustic Performances of Bladeless Fans","authors":"Ang Li, Jun Chen, Yangfan Liu, J. Bolton, P. Davies","doi":"10.1115/ajkfluids2019-5220","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5220","url":null,"abstract":"\u0000 In recent years, the bladeless fan that does not have visible impellers have been widely applied in household appliances. Since the customers are particularly sensitive to noise and the strength of wind generated by the fan, the aerodynamic and acoustic performances of the fan need to be accurately characterized in the design stage. In this study, computational fluid dynamic (CFD) and computational aeroacoustics (CAA) are applied to investigate the performances of different designs of a bladeless fan model. The influence of four parameters, namely the airfoil selection for cross-section of the wind channel, the slit width, the height of cross-section and the location of the slit, is investigated. The results indicate the streamwise air velocity increases significantly by narrowing the outlet, but the noise level increases simultaneously. In addition, the generated noise increases while the height of fan cross-section increases, and a 4mm height of the cross section is optimal for aerodynamic performance. When the slit is closer to the location of maximum thickness, the performances of the bladeless fan increases. Moreover, the performance is not changed significantly by changing the cross-sectional profile. Finally, the optimal geometric parameters are identified to guide the future design of the bladeless fan.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116207304","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}
Pub Date : 2019-11-20DOI: 10.1115/ajkfluids2019-5432
S. Jang, J. Park, Sang Hyeon Han, Hong-Jip Kim, K. Jung, C. Yoo
In this study, the auto ignition with low limit temperature of syngas has been numerically investigated using a 2-D numerical analysis. Previous study showed that auto ignition was observed at above 860 K in co-flow jet experiments using syngas and dry air. However, the auto ignition at this low temperature range could not be predicted with existing chemical mechanisms. Inconsistency of the auto ignition temperature between the experimental and numerical results is thought to be due to the inaccuracy of the chemical kinetic mechanism. The prediction of ignition delay time and sensitivity analysis for each chemical kinetic mechanism were performed to verify the reasons of the inconsistency between the experimental and numerical results. The results which were calculated using the various mechanisms showed significantly differences in the ignition delay time. In this study, we intend to analyze the reason of discrepancy to predict the auto ignition with low pressure and low temperature region of syngas and to improve the chemical kinetic mechanism. A sensitive analysis has been done to investigate the reaction steps which affected the ignition delay time significantly, and the reaction rate of the selected reaction step was modified. Through the modified chemical kinetic mechanism, we could identify the auto ignition in the low temperature region from the 2-D numerical results. Then CEMA (Chemical Explosive Mode Analysis) was used to validate the 2-D numerical analysis with modified chemical kinetic mechanism. From the validation, the calculated λexp, EI, and PI showed reasonable results, so we expect that the modified chemical kinetic mechanism can be used in various low temperature region.
{"title":"A Numerical Study on the Low Limit Auto-Ignition Temperature of Syngas and Modification of Chemical Kinetic Mechanism","authors":"S. Jang, J. Park, Sang Hyeon Han, Hong-Jip Kim, K. Jung, C. Yoo","doi":"10.1115/ajkfluids2019-5432","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5432","url":null,"abstract":"\u0000 In this study, the auto ignition with low limit temperature of syngas has been numerically investigated using a 2-D numerical analysis. Previous study showed that auto ignition was observed at above 860 K in co-flow jet experiments using syngas and dry air. However, the auto ignition at this low temperature range could not be predicted with existing chemical mechanisms. Inconsistency of the auto ignition temperature between the experimental and numerical results is thought to be due to the inaccuracy of the chemical kinetic mechanism. The prediction of ignition delay time and sensitivity analysis for each chemical kinetic mechanism were performed to verify the reasons of the inconsistency between the experimental and numerical results. The results which were calculated using the various mechanisms showed significantly differences in the ignition delay time. In this study, we intend to analyze the reason of discrepancy to predict the auto ignition with low pressure and low temperature region of syngas and to improve the chemical kinetic mechanism. A sensitive analysis has been done to investigate the reaction steps which affected the ignition delay time significantly, and the reaction rate of the selected reaction step was modified. Through the modified chemical kinetic mechanism, we could identify the auto ignition in the low temperature region from the 2-D numerical results. Then CEMA (Chemical Explosive Mode Analysis) was used to validate the 2-D numerical analysis with modified chemical kinetic mechanism. From the validation, the calculated λexp, EI, and PI showed reasonable results, so we expect that the modified chemical kinetic mechanism can be used in various low temperature region.","PeriodicalId":403423,"journal":{"name":"Volume 3A: Fluid Applications and Systems","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115244545","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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