Chloé Carer, Leonhard Xaver Driever, Stein Köbben, Max Mckenzie, Fredrik Rhenman, Onno Van de Sype, J. V. D. Toorn, C. V. Wezel, Constança Miranda de Andrade Veiga, Aleksandrs Vinarskis, B. Jyoti
This research investigated how the variation of temperature and shear rate affects the viscosity of ethanol gel propellants that use methyl cellulose as gellant and, in parts, use boron as energetic additive. Using a rotational viscometer in a cone-and-plate configuration, propellant viscosity data was recorded across a range of temperatures and applied shear rates. The temperature dependence of the viscosity was modelled using an Arrhenius-type equation. For the high shear rates, the data was modelled using the Power Law, Herrschel–Bulkley model, Carreau model, and Cross model. For low shear rates the used model was the rearranged Herrschel–Bulkley model. The temperature investigation suggested that the trend of decreasing viscosity with increasing temperature, predicted by the Arrhenius-type equation, is only applicable until approximately 320 K, after which the gel viscosity increased strongly. At high shear rates, the gel behaved in a shear thinning manner and was modelled most accurately by the Cross model. At low shear rates, the gel was shear thickening up to its elastic limit, which was found to lie at 0.41 s–1.
{"title":"Effect of Parameter Variation on the Viscosity of Ethanol Gel Propellants","authors":"Chloé Carer, Leonhard Xaver Driever, Stein Köbben, Max Mckenzie, Fredrik Rhenman, Onno Van de Sype, J. V. D. Toorn, C. V. Wezel, Constança Miranda de Andrade Veiga, Aleksandrs Vinarskis, B. Jyoti","doi":"10.1590/JATM.V13.1196","DOIUrl":"https://doi.org/10.1590/JATM.V13.1196","url":null,"abstract":"This research investigated how the variation of temperature and shear rate affects the viscosity of ethanol gel propellants that use methyl cellulose as gellant and, in parts, use boron as energetic additive. Using a rotational viscometer in a cone-and-plate configuration, propellant viscosity data was recorded across a range of temperatures and applied shear rates. The temperature dependence of the viscosity was modelled using an Arrhenius-type equation. For the high shear rates, the data was modelled using the Power Law, Herrschel–Bulkley model, Carreau model, and Cross model. For low shear rates the used model was the rearranged Herrschel–Bulkley model. The temperature investigation suggested that the trend of decreasing viscosity with increasing temperature, predicted by the Arrhenius-type equation, is only applicable until approximately 320 K, after which the gel viscosity increased strongly. At high shear rates, the gel behaved in a shear thinning manner and was modelled most accurately by the Cross model. At low shear rates, the gel was shear thickening up to its elastic limit, which was found to lie at 0.41 s–1.","PeriodicalId":14872,"journal":{"name":"Journal of Aerospace Technology and Management","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47833221","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}
Methods based on received signal strength measurements (RSS measurements) are used to determine the unmanned aerial vehicle (UAV) location using a wireless sensor network. The UAV transmitter power is usually unknown. In real conditions, it often becomes necessary to consider existence of anomalous measurement results. The reasons for the violation of the measurement process can be: the influence of interference, errors in the identification of signals during primary processing, failures of the equipment and similar. The optimum and quasi-optimal adaptive algorithms of UAV movement parameters filtration based on the RSS-measurement sensor networks in the presence of anomalous measurements at the unknown power of the transmitter are developed. These algorithms are obtained using Bayes’ theorems and the Markov property of a mixed process, including a vector of target movement parameters and a discrete component characterizing the type of measurement. Analysis of developed algorithm performance was carried out by Monte Carlo method on 2D plane. The quasi-optimal adaptive filtering algorithm detects the appearance of anomalous measurements with probabilities close to unity and allows one to eliminate their influence on the accuracy of UAV movement parameters estimation and also to estimate the UAV unknown transmitter power.
{"title":"Filtration of UAV Movement Parameters Based on the Received Signal Strength Measurement Sensor Networks in the Presence of Anomalous Measurements of Unknown Power at the Transmitter","authors":"I. Tovkach, S. Zhuk","doi":"10.1590/JATM.V13.1191","DOIUrl":"https://doi.org/10.1590/JATM.V13.1191","url":null,"abstract":"Methods based on received signal strength measurements (RSS measurements) are used to determine the unmanned aerial vehicle (UAV) location using a wireless sensor network. The UAV transmitter power is usually unknown. In real conditions, it often becomes necessary to consider existence of anomalous measurement results. The reasons for the violation of the measurement process can be: the influence of interference, errors in the identification of signals during primary processing, failures of the equipment and similar. The optimum and quasi-optimal adaptive algorithms of UAV movement parameters filtration based on the RSS-measurement sensor networks in the presence of anomalous measurements at the unknown power of the transmitter are developed. These algorithms are obtained using Bayes’ theorems and the Markov property of a mixed process, including a vector of target movement parameters and a discrete component characterizing the type of measurement. Analysis of developed algorithm performance was carried out by Monte Carlo method on 2D plane. The quasi-optimal adaptive filtering algorithm detects the appearance of anomalous measurements with probabilities close to unity and allows one to eliminate their influence on the accuracy of UAV movement parameters estimation and also to estimate the UAV unknown transmitter power.","PeriodicalId":14872,"journal":{"name":"Journal of Aerospace Technology and Management","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48704027","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}
Ariane Aparecida Teixeira de Souza, Nila Cecília de Farias Lopes Medeiros, L. I. Medeiros, G. Amaral-Labat, Matheus Carvalho Bispo, G. L. E. Lenz e Silva, A. F. N. Boss, M. Baldan
Radar absorbing materials (RAMs) are composites made with a polymeric matrix and an electromagnetic absorbing filler, such as carbon black (CB), silicon carbide (SiC) or manganese zinc ferrite (MnZn). To enhance their performances to attenuate an incident wave through reflection loss (RL), RAMs can be produced in multilayer structures. Usually, the RL analysis is done theoretically and experimentally validated with free space analysis. Here, it was demonstrated that multilayer structure can be designed and easily validated using rectangular waveguide, using a simpler setup and small samples. Three composites were produced using 2 wt% of CB (CB2), 40 wt% of SiC (SiC40) and 60 wt% of MnZn (MnZn60). They were characterized over the Ku-band and used to validate the multilayer structures, that were prepared by simply stacking each material inside the waveguide sample holder. One of the best results was obtained with structure SiC40+CB2 with 5.85 mm thickness, that presented a calculated RL of -21 dB at 17.8 GHz and a measured RL of -36 dB at the same frequency. In conclusion, using rectangular waveguide has been proven to be an easy, cheap, precise and fast approach to validate multilayer structures designs.
{"title":"Double Layer Material Designed to Reduce Electromagnetic Radiation with Carbon Black, Silicon Carbide and Manganese Zinc Ferrite","authors":"Ariane Aparecida Teixeira de Souza, Nila Cecília de Farias Lopes Medeiros, L. I. Medeiros, G. Amaral-Labat, Matheus Carvalho Bispo, G. L. E. Lenz e Silva, A. F. N. Boss, M. Baldan","doi":"10.1590/JATM.V13.1199","DOIUrl":"https://doi.org/10.1590/JATM.V13.1199","url":null,"abstract":"Radar absorbing materials (RAMs) are composites made with a polymeric matrix and an electromagnetic absorbing filler, such as carbon black (CB), silicon carbide (SiC) or manganese zinc ferrite (MnZn). To enhance their performances to attenuate an incident wave through reflection loss (RL), RAMs can be produced in multilayer structures. Usually, the RL analysis is done theoretically and experimentally validated with free space analysis. Here, it was demonstrated that multilayer structure can be designed and easily validated using rectangular waveguide, using a simpler setup and small samples. Three composites were produced using 2 wt% of CB (CB2), 40 wt% of SiC (SiC40) and 60 wt% of MnZn (MnZn60). They were characterized over the Ku-band and used to validate the multilayer structures, that were prepared by simply stacking each material inside the waveguide sample holder. One of the best results was obtained with structure SiC40+CB2 with 5.85 mm thickness, that presented a calculated RL of -21 dB at 17.8 GHz and a measured RL of -36 dB at the same frequency. In conclusion, using rectangular waveguide has been proven to be an easy, cheap, precise and fast approach to validate multilayer structures designs.","PeriodicalId":14872,"journal":{"name":"Journal of Aerospace Technology and Management","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48299271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The life test of the 30 cm diameter ion thruster developed by the Lanzhou institute of physics began in Apr. 2018 and ended in Jan. 2020, lasting 6,500 h. This paper introduces the results of the 6,500-h life test of the 30 cm diameter ion thruster completed on the ground, including the ground facility for life test, the variations of the thrusters working performance, the times of the breakdown and power restart, and the erosion of the key components. The results show that the performance parameters, such as thrust, specific impulse and efficiency, do not change obviously during the test and magnetic field of the discharge chamber has no change. With the increase of test time, breakdown times increased significantly, whereas the power restart time decreased correspondingly. The diameter of the cathode orifice decreases gradually and there is a blockage risk of orifice. However, the diameter of the keeper orifice increases and presents an inverted cone erosion pattern. The diameter of the decelerator grid aperture expanded from 1.6 to 1.8 mm from 0 to 1,000 h and slightly enlarged after that. The aperture diameter of the accelerator grid presented linear enlargement but the pits-and-grooves erosion is obvious.
{"title":"The 6,500-H Life Test Results of 30 cm Diameter Ion Thruster","authors":"Sun Mingming, Geng Hai, Zheng Yi","doi":"10.1590/JATM.V13.1202","DOIUrl":"https://doi.org/10.1590/JATM.V13.1202","url":null,"abstract":"The life test of the 30 cm diameter ion thruster developed by the Lanzhou institute of physics began in Apr. 2018 and ended in Jan. 2020, lasting 6,500 h. This paper introduces the results of the 6,500-h life test of the 30 cm diameter ion thruster completed on the ground, including the ground facility for life test, the variations of the thrusters working performance, the times of the breakdown and power restart, and the erosion of the key components. The results show that the performance parameters, such as thrust, specific impulse and efficiency, do not change obviously during the test and magnetic field of the discharge chamber has no change. With the increase of test time, breakdown times increased significantly, whereas the power restart time decreased correspondingly. The diameter of the cathode orifice decreases gradually and there is a blockage risk of orifice. However, the diameter of the keeper orifice increases and presents an inverted cone erosion pattern. The diameter of the decelerator grid aperture expanded from 1.6 to 1.8 mm from 0 to 1,000 h and slightly enlarged after that. The aperture diameter of the accelerator grid presented linear enlargement but the pits-and-grooves erosion is obvious.","PeriodicalId":14872,"journal":{"name":"Journal of Aerospace Technology and Management","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47165591","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 presents selected results of an unconventional aircraft development campaign. Engine installation at the rear part of the fuselage imposed design constraints for air intakes that should be used for cooling purposes. Trial and error flight tests increased the development cost and time which required a more sophisticated analysis through computational fluid dynamics (CFD) techniques and robust semiempirical approach. The carried-out investigation of the air intakes started with an empirical approach from guidelines for designing NACA and scoops. Numerical studies via computational fluid dynamics were performed with the air intakes installed in the aircraft fuselage. An analysis based on the air intake efficiency, drag and the effect of angle of attack are detailed in this work. Different air intakes designs, such as scoops of different shapes, were evaluated seeking for improved air intake efficiency and low drag while providing enough air for cooling the engine compartment. The results showed that the numerical approach used herein decreased the development cost and time of the aircraft, providing a reasonable low-cost approach and leading to a design selection more easily. Based on the current approach the canard airplane geometry was changed to account for the new selected air intake for engine cooling purposes.
{"title":"A Numerical Approach for Implementing Air Intakes in a Canard Type Aircraft for Engine Cooling Purposes","authors":"O. Almeida, P. Souza, E. Cunha","doi":"10.1590/JATM.V13.1192","DOIUrl":"https://doi.org/10.1590/JATM.V13.1192","url":null,"abstract":"This work presents selected results of an unconventional aircraft development campaign. Engine installation at the rear part of the fuselage imposed design constraints for air intakes that should be used for cooling purposes. Trial and error flight tests increased the development cost and time which required a more sophisticated analysis through computational fluid dynamics (CFD) techniques and robust semiempirical approach. The carried-out investigation of the air intakes started with an empirical approach from guidelines for designing NACA and scoops. Numerical studies via computational fluid dynamics were performed with the air intakes installed in the aircraft fuselage. An analysis based on the air intake efficiency, drag and the effect of angle of attack are detailed in this work. Different air intakes designs, such as scoops of different shapes, were evaluated seeking for improved air intake efficiency and low drag while providing enough air for cooling the engine compartment. The results showed that the numerical approach used herein decreased the development cost and time of the aircraft, providing a reasonable low-cost approach and leading to a design selection more easily. Based on the current approach the canard airplane geometry was changed to account for the new selected air intake for engine cooling purposes.","PeriodicalId":14872,"journal":{"name":"Journal of Aerospace Technology and Management","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47147535","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}
Humberto Dorneles Santa Maria, R. Frogeri, Fabricio Pelloso Piurcosky, Liz Áurea Prado
This study analyzed Remotely Piloted Aircraft System (RPAS) deployment in the Regional Services of Aeronautical Accidents Investigation and Prevention (SERIPA – Brazil) as a support tool to investigate aviation accidents. Such review is justified by the acquisition and use of this equipment and new technology by investigators since 2017. Research aim was to analyze the perception of SERIPA investigators regarding the usefulness and ease of use of the RPAS equipment. We applied an adaptation of the Theoretical Model of Technology. Methodologically, the study was characterized as exploratory and carried out through an inductive logic and qualitative approach. A case study has been done with 14 investigators belonging to six Brazilian SERIPA units. In conclusion, the respondents deem the RPAS to be useful for aircraft accident investigation, and the equipment is of easy use. RPAS was observed as a tool capable of replacing manned aircraft in some crash sites. The external variable, i.e. crash site characteristics, emerged as a factor that influences the use of RPAS, as well as the transport of RPAS in commercial aircraft.
{"title":"Remotely Piloted Aircraft: Analysis of the Deployment in Aeronautical Accident Investigation Bureau","authors":"Humberto Dorneles Santa Maria, R. Frogeri, Fabricio Pelloso Piurcosky, Liz Áurea Prado","doi":"10.1590/JATM.V13.1187","DOIUrl":"https://doi.org/10.1590/JATM.V13.1187","url":null,"abstract":"This study analyzed Remotely Piloted Aircraft System (RPAS) deployment in the Regional Services of Aeronautical Accidents Investigation and Prevention (SERIPA – Brazil) as a support tool to investigate aviation accidents. Such review is justified by the acquisition and use of this equipment and new technology by investigators since 2017. Research aim was to analyze the perception of SERIPA investigators regarding the usefulness and ease of use of the RPAS equipment. We applied an adaptation of the Theoretical Model of Technology. Methodologically, the study was characterized as exploratory and carried out through an inductive logic and qualitative approach. A case study has been done with 14 investigators belonging to six Brazilian SERIPA units. In conclusion, the respondents deem the RPAS to be useful for aircraft accident investigation, and the equipment is of easy use. RPAS was observed as a tool capable of replacing manned aircraft in some crash sites. The external variable, i.e. crash site characteristics, emerged as a factor that influences the use of RPAS, as well as the transport of RPAS in commercial aircraft.","PeriodicalId":14872,"journal":{"name":"Journal of Aerospace Technology and Management","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48915909","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}
Gustavo Paulinelli Guimarães, R. Pirk, C. Souto, L. Góes
Combustion instability can severely impair the operation of many kinds of combustion engines. Acoustic resonators are widely used to suppress the pressure oscillations caused by the coupling between the combustion process and the combustion chamber acoustic modes. Combustion chambers with subsonic flow in its inlets and outlets, like gas turbine combustors, exhibit some acoustical damping due to the presence of openings. In such chambers, the acoustic modes are complex. In a complex mode, the antinode regions can be shifted from its position in the corresponding real mode. In this work an experimental acoustic modal analysis of a cavity with an opening was performed. Acoustic frequency response functions were obtained by using a volume acceleration source, a microphone and a data acquisition system. The PolyMAX algorithm was used to estimate longitudinal modes in its real and complex versions. A comparison was performed and the results show that, for some modes, the antinode region placement could change reasonably. This suggests that the use of complex modes for location of antinode regions provides more accurate results and consequently could be a better way to identify positions, where resonators provide maximum damping in order to minimize combustion instability in subsonic combustion chambers.
{"title":"Investigations on Complex Acoustic Modes of Rocket Engines Combustion Chambers for Damping Allocation","authors":"Gustavo Paulinelli Guimarães, R. Pirk, C. Souto, L. Góes","doi":"10.1590/JATM.V13.1198","DOIUrl":"https://doi.org/10.1590/JATM.V13.1198","url":null,"abstract":"Combustion instability can severely impair the operation of many kinds of combustion engines. Acoustic resonators are widely used to suppress the pressure oscillations caused by the coupling between the combustion process and the combustion chamber acoustic modes. Combustion chambers with subsonic flow in its inlets and outlets, like gas turbine combustors, exhibit some acoustical damping due to the presence of openings. In such chambers, the acoustic modes are complex. In a complex mode, the antinode regions can be shifted from its position in the corresponding real mode. In this work an experimental acoustic modal analysis of a cavity with an opening was performed. Acoustic frequency response functions were obtained by using a volume acceleration source, a microphone and a data acquisition system. The PolyMAX algorithm was used to estimate longitudinal modes in its real and complex versions. A comparison was performed and the results show that, for some modes, the antinode region placement could change reasonably. This suggests that the use of complex modes for location of antinode regions provides more accurate results and consequently could be a better way to identify positions, where resonators provide maximum damping in order to minimize combustion instability in subsonic combustion chambers.","PeriodicalId":14872,"journal":{"name":"Journal of Aerospace Technology and Management","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49052641","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}
{"title":"Open Science to Knowledge without Borders","authors":"Elizabeth da Costa Mattos","doi":"10.1590/JATM.V13.1212","DOIUrl":"https://doi.org/10.1590/JATM.V13.1212","url":null,"abstract":"","PeriodicalId":14872,"journal":{"name":"Journal of Aerospace Technology and Management","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41351684","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}
In this study, surface features such as dimples and bumps are introduced to the surface of a NACA 0012 airfoil to study their effect on boundary layer separation, particularly at high angles of attack. Six modified airfoils were designed with dimples and bumps of spherical and pyramidical shapes. A computational fluid dynamics (CFD) analysis was conducted on these models at subsonic flow using Ansys Fluent. The analysis used the Shear Stress Transport k – ω turbulence model at a varying angle of attack (AOA) from 0 to 15°. The velocity contours and streamlines were generated. Also, the lift coefficient, drag coefficient and the lift-to-drag performance ratio were computed and analyzed. The results showed that all surface modifications led to delayed flow separation and flow recirculation. All surface modification also resulted in a decrease in drag at 15°. All designs, except pyramidical protrusions, increased the lift-to-drag ratio (L/D) performance at 15°. It was found that dimples are better than bumps and spherical features are better than pyramidical ones. on
{"title":"Influence of Spherical and Pyramidical Dimples and Bumps on Airfoil Performance in Subsonic Flow","authors":"Zahra Mehtar, Afaq Altaf","doi":"10.1590/JATM.V13.1219","DOIUrl":"https://doi.org/10.1590/JATM.V13.1219","url":null,"abstract":"In this study, surface features such as dimples and bumps are introduced to the surface of a NACA 0012 airfoil to study their effect on boundary layer separation, particularly at high angles of attack. Six modified airfoils were designed with dimples and bumps of spherical and pyramidical shapes. A computational fluid dynamics (CFD) analysis was conducted on these models at subsonic flow using Ansys Fluent. The analysis used the Shear Stress Transport k – ω turbulence model at a varying angle of attack (AOA) from 0 to 15°. The velocity contours and streamlines were generated. Also, the lift coefficient, drag coefficient and the lift-to-drag performance ratio were computed and analyzed. The results showed that all surface modifications led to delayed flow separation and flow recirculation. All surface modification also resulted in a decrease in drag at 15°. All designs, except pyramidical protrusions, increased the lift-to-drag ratio (L/D) performance at 15°. It was found that dimples are better than bumps and spherical features are better than pyramidical ones. on","PeriodicalId":14872,"journal":{"name":"Journal of Aerospace Technology and Management","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67185330","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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