Pub Date : 2024-05-01DOI: 10.47176/jafm.17.05.2193
Z. G. Lei, C. Q. Shen, C. C. Song, F. Yao, X. D. Liu
Droplet evaporation coupled with gravity and surface tension on a wall with the radial temperature gradients is numerically studied with the arbitrary Lagrangian‒Eulerian method. The influence of the wall temperature distribution on the droplet evaporation process, which is less considered in the existing literature, is mainly discussed. The droplet temperature coefficient of the surface tension and the viscosity on the droplet profile evolution, flow, heat and mass transfer characteristic are also discussed. The results indicate that the droplets become flat first and then retract under the gravity and Marangoni convection during droplet evaporation. There are two high-velocity regions inside the evaporating droplet. One region is at the droplet axis, in which fluid flows to the wall from the droplet top. The other region is near the droplet surface, where fluid flows to the droplet top. There are turning points on the two sides of which the influence of wall temperature distribution on the ratio between the droplet height and the radius of the three-phase contact line ( h / R c ), the velocity in the droplet and the surface temperature converts. All of them are larger before the turning point when the wall temperature slope is
{"title":"Sessile Droplet Evaporation on Wall with Radial Temperature Gradient","authors":"Z. G. Lei, C. Q. Shen, C. C. Song, F. Yao, X. D. Liu","doi":"10.47176/jafm.17.05.2193","DOIUrl":"https://doi.org/10.47176/jafm.17.05.2193","url":null,"abstract":"Droplet evaporation coupled with gravity and surface tension on a wall with the radial temperature gradients is numerically studied with the arbitrary Lagrangian‒Eulerian method. The influence of the wall temperature distribution on the droplet evaporation process, which is less considered in the existing literature, is mainly discussed. The droplet temperature coefficient of the surface tension and the viscosity on the droplet profile evolution, flow, heat and mass transfer characteristic are also discussed. The results indicate that the droplets become flat first and then retract under the gravity and Marangoni convection during droplet evaporation. There are two high-velocity regions inside the evaporating droplet. One region is at the droplet axis, in which fluid flows to the wall from the droplet top. The other region is near the droplet surface, where fluid flows to the droplet top. There are turning points on the two sides of which the influence of wall temperature distribution on the ratio between the droplet height and the radius of the three-phase contact line ( h / R c ), the velocity in the droplet and the surface temperature converts. All of them are larger before the turning point when the wall temperature slope is","PeriodicalId":49041,"journal":{"name":"Journal of Applied Fluid Mechanics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141054866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-01DOI: 10.47176/jafm.17.05.2089
†. A.Leousidis, E. Keramaris, G. Pechlivanidis, Y. Savvidis
In this study the effect of cooling load on the surface water of an open channel with different flow depths is investigated. The method, which was used, involves an experimental laboratory set-up that contains a well-insulated cooling load over a finite area of the water surface, without direct contact with the free water surface so that losses of load to the environment should be avoided. The different cooling loads for each experiment were achieved with the use of insulating films. The insulating film is placed at the bottom of the experimental set-up where there was an empty surface (gap - D), through which the cooling load is allowed to pass. The measurement of velocities was carried out at a two-dimensional (XZ) field, with the help of a digital camera. The recording of motion of the dye (rhodamine) along the channel per unit of time, allows the calculation of the values of the velocity fields. Measurements were conducted when the phenomenon becomes steady. The results for the determination of the cold mass length as a function of the flow depth, and the temperature difference ΔT, in a state of thermal equilibrium, led to the formation of a new mathematical relationship. Further study of the phenomenon is essential for the improvement of this study, in combination with other parameters that affect the aquatic ecosystem.
{"title":"Study of the Effect of a Cooling Load on a Fluid Surface (Water) in an Open Channel","authors":"†. A.Leousidis, E. Keramaris, G. Pechlivanidis, Y. Savvidis","doi":"10.47176/jafm.17.05.2089","DOIUrl":"https://doi.org/10.47176/jafm.17.05.2089","url":null,"abstract":"In this study the effect of cooling load on the surface water of an open channel with different flow depths is investigated. The method, which was used, involves an experimental laboratory set-up that contains a well-insulated cooling load over a finite area of the water surface, without direct contact with the free water surface so that losses of load to the environment should be avoided. The different cooling loads for each experiment were achieved with the use of insulating films. The insulating film is placed at the bottom of the experimental set-up where there was an empty surface (gap - D), through which the cooling load is allowed to pass. The measurement of velocities was carried out at a two-dimensional (XZ) field, with the help of a digital camera. The recording of motion of the dye (rhodamine) along the channel per unit of time, allows the calculation of the values of the velocity fields. Measurements were conducted when the phenomenon becomes steady. The results for the determination of the cold mass length as a function of the flow depth, and the temperature difference ΔT, in a state of thermal equilibrium, led to the formation of a new mathematical relationship. Further study of the phenomenon is essential for the improvement of this study, in combination with other parameters that affect the aquatic ecosystem.","PeriodicalId":49041,"journal":{"name":"Journal of Applied Fluid Mechanics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141037172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-01DOI: 10.47176/jafm.17.05.2333
B. Hao, Q. Jiang, C. Xu, L. Liu
The bullet shape is critical in efficient bullet design because it affects the lift and drag forces. This paper proposes a new bullet shape with a logarithmic curve and analyzes the lift and drag coefficients of bullets with different curves under different angles of attack. The results are compared with a bullet whose shape is described by the power law curve. Fluent simulations demonstrate that the optimal power exponent values are 0.65, 0.6, and 0.65 for the bullet with the power law curve and 1.3, 1, and 1 for the bullet with the logarithmic curve at 0°, 30°, and 40° angles of attack, respectively. At a 0° angle of attack, the lift coefficient of the logarithmic curve is the largest. The lift force of the bullet with the logarithmic curve is 129.4% higher than that with the von Karman curve. The drag coefficient is the largest for the bullet with the rectilinear curve; it is 1.30% larger than that of the bullet with the logarithmic curve. At 30° and 40° angles of attack, the lift coefficient of the bullet with the power law curve is larger. The difference in the lift coefficients between the two angles of attack is 18.47%. The bullet’s drag coefficient is the largest for the logarithmic curve, and the difference in the drag coefficients between the two angles of attack is 18.59%.
{"title":"Aerodynamic Characterization of Bullet Heads with Different Arcuate Curves","authors":"B. Hao, Q. Jiang, C. Xu, L. Liu","doi":"10.47176/jafm.17.05.2333","DOIUrl":"https://doi.org/10.47176/jafm.17.05.2333","url":null,"abstract":"The bullet shape is critical in efficient bullet design because it affects the lift and drag forces. This paper proposes a new bullet shape with a logarithmic curve and analyzes the lift and drag coefficients of bullets with different curves under different angles of attack. The results are compared with a bullet whose shape is described by the power law curve. Fluent simulations demonstrate that the optimal power exponent values are 0.65, 0.6, and 0.65 for the bullet with the power law curve and 1.3, 1, and 1 for the bullet with the logarithmic curve at 0°, 30°, and 40° angles of attack, respectively. At a 0° angle of attack, the lift coefficient of the logarithmic curve is the largest. The lift force of the bullet with the logarithmic curve is 129.4% higher than that with the von Karman curve. The drag coefficient is the largest for the bullet with the rectilinear curve; it is 1.30% larger than that of the bullet with the logarithmic curve. At 30° and 40° angles of attack, the lift coefficient of the bullet with the power law curve is larger. The difference in the lift coefficients between the two angles of attack is 18.47%. The bullet’s drag coefficient is the largest for the logarithmic curve, and the difference in the drag coefficients between the two angles of attack is 18.59%.","PeriodicalId":49041,"journal":{"name":"Journal of Applied Fluid Mechanics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141047390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Flow Modeling in the Wake of a Francis Turbine with Hydraulic Charge: Case of Songloulou-Cameroon","authors":"","doi":"10.47176/jafm.17.4.1900","DOIUrl":"https://doi.org/10.47176/jafm.17.4.1900","url":null,"abstract":"","PeriodicalId":49041,"journal":{"name":"Journal of Applied Fluid Mechanics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140353938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Investigating the Impact of Back Cavity Filling and Axial Clearance on the Flow Physics and Performance of a Pump as Turbine","authors":"","doi":"10.47176/jafm.17.4.2256","DOIUrl":"https://doi.org/10.47176/jafm.17.4.2256","url":null,"abstract":"","PeriodicalId":49041,"journal":{"name":"Journal of Applied Fluid Mechanics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140356656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Effect of Semi-elliptical Outer Blade-surface on the Savonius Hydrokinetic Turbine Performance: A Numerical Investigation","authors":"","doi":"10.47176/jafm.17.4.2235","DOIUrl":"https://doi.org/10.47176/jafm.17.4.2235","url":null,"abstract":"","PeriodicalId":49041,"journal":{"name":"Journal of Applied Fluid Mechanics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140356484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Effect of Blade Slot Positioning Close to Blade Root on the Performance of Highly Loaded Helium Compressor","authors":"","doi":"10.47176/jafm.17.4.2200","DOIUrl":"https://doi.org/10.47176/jafm.17.4.2200","url":null,"abstract":"","PeriodicalId":49041,"journal":{"name":"Journal of Applied Fluid Mechanics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140354105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Flow Field Analysis of Francis Turbine Draft Tube using POD at Design and Part Load Operating Conditions","authors":"","doi":"10.47176/jafm.17.4.2274","DOIUrl":"https://doi.org/10.47176/jafm.17.4.2274","url":null,"abstract":"","PeriodicalId":49041,"journal":{"name":"Journal of Applied Fluid Mechanics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140353252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Study on the Effect of Bridge Windbreaks on the Aerodynamic Characteristics of High-Speed Trains Meeting under Crosswind","authors":"","doi":"10.47176/jafm.17.4.2204","DOIUrl":"https://doi.org/10.47176/jafm.17.4.2204","url":null,"abstract":"","PeriodicalId":49041,"journal":{"name":"Journal of Applied Fluid Mechanics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140355974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Investigation of the Flow-Induced Noise and Optimization Design of a Short Tube Throttle Valve","authors":"","doi":"10.47176/jafm.17.4.2018","DOIUrl":"https://doi.org/10.47176/jafm.17.4.2018","url":null,"abstract":"","PeriodicalId":49041,"journal":{"name":"Journal of Applied Fluid Mechanics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140356736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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