The marine propeller typically functions within thefilowfiield generated by a water vehicle.Investigations into the geometric parameters of the propeller are commonly conducted under open‑water conditions as simultane...The marine propeller typically functions within thefilowfiield generated by a water vehicle.Investigations into the geometric parameters of the propeller are commonly conducted under open‑water conditions as simultaneously simulating both vehicle and propeller holds several computational challenges.While during operation,this propellant device must face several forces like gravity,hydrodynamic load,and centrifugal force,which cause different problems like cavitation and structural failure,etc.Since these issues affect performance,it necessitates comprehensive analysis.In this study,hydrodynamic analysis is performed by using commercial software STAR CCM+.In hydrodynamic analysis,the effect of the rake angles–5°,5°,10°and 15°on hydrodynamic coeffiicients and effiiciency of the DTMB 4119 in the open water is analyzed using Computational Fluid Dynamics(CFD)and the control volume approach.The Shear Stress Transport(SST)k‑ωturbulence model is used in Computational Fluid Dynamics(CFD)simulation.Hydrodynamic analysis reveals that the rake angles 5°and 10°cause the open water effiiciency of David Taylor Model Basin(DTMB)4119 to improve by 0.4 to 1.32%with exception of the rake angles–5°and 15°,which possess different effects on effiiciency.The angle–5°causes a decrease in propeller effiiciency under heavy loading situations(low advance coeffiicient)apart from a minorfiluctuation at light loading conditions(high advance coeffiicient),while the angle 15°produces a drop in effiiciency by higher advance ratios but little variation at lower advance ratios.展开更多
Giorgio Vasari’s educational background and association with Renaissance humanists engendered his familiarity with the texts and imagery of classical,emblematic,and mythographic traditions.Vasari’s composition of im...Giorgio Vasari’s educational background and association with Renaissance humanists engendered his familiarity with the texts and imagery of classical,emblematic,and mythographic traditions.Vasari’s composition of images as a compendium of iconography for a decorative program was in the vein of the literary practices of Andrea Alciato(1482-1550),Pierio Valeriano(1477-1558),and Vincenzo Cartari(1531-1590),and followed Paolo Giovio’s advice on how to depict an emblematic image or impresa1(Giovio,1559,p.9).For Giovio(1483-1552),an impresa or badge must contain a figure and motto,its meaning should be clear and precise,the imagery must be pleasant to look at,and the motto must be brief,inventive,and unambiguous.But sometimes Vasari did not follow his advice,relying more on the Renaissance Neoplatonic notion of a concept postulated by the Florentine philosopher Marsilio Ficino(1433-1499).In De vita coelitus comparanda(How Life Should Be Arranged According to the Heavens)2(Ficino,1489;1561-1563;1996,pp.7-19;Kerrigan&Braden,1989,pp.101-115).Ficino discusses the use and the magic potency of images by deliberating on the virtue of imagery,what power pertains to the figure in the Heavens and on Earth,which of the heavenly configurations are impressed on images by the ancients,and how the images are employed in antiquity3(Gombrich,1972,p.172;Chastel,1996,pp.81-89;Moore,1990,p.20,137,181;Bull,2006,pp.7-36).Vasari assimilated these concepts visually in the fresco painting of the Bride with a Rake(1548),located in one of the rooms in his house in Arezzo,the Chamber of Fortune(Chamber of Virtue),where he composed a paradoxical iconographic image-the subject of this essay.This essay is composed of two parts:an introduction to the location of the painting in the Casa Vasari in Arezzo and an iconographical and iconological interpretation of the imagery.展开更多
文摘The marine propeller typically functions within thefilowfiield generated by a water vehicle.Investigations into the geometric parameters of the propeller are commonly conducted under open‑water conditions as simultaneously simulating both vehicle and propeller holds several computational challenges.While during operation,this propellant device must face several forces like gravity,hydrodynamic load,and centrifugal force,which cause different problems like cavitation and structural failure,etc.Since these issues affect performance,it necessitates comprehensive analysis.In this study,hydrodynamic analysis is performed by using commercial software STAR CCM+.In hydrodynamic analysis,the effect of the rake angles–5°,5°,10°and 15°on hydrodynamic coeffiicients and effiiciency of the DTMB 4119 in the open water is analyzed using Computational Fluid Dynamics(CFD)and the control volume approach.The Shear Stress Transport(SST)k‑ωturbulence model is used in Computational Fluid Dynamics(CFD)simulation.Hydrodynamic analysis reveals that the rake angles 5°and 10°cause the open water effiiciency of David Taylor Model Basin(DTMB)4119 to improve by 0.4 to 1.32%with exception of the rake angles–5°and 15°,which possess different effects on effiiciency.The angle–5°causes a decrease in propeller effiiciency under heavy loading situations(low advance coeffiicient)apart from a minorfiluctuation at light loading conditions(high advance coeffiicient),while the angle 15°produces a drop in effiiciency by higher advance ratios but little variation at lower advance ratios.
文摘Giorgio Vasari’s educational background and association with Renaissance humanists engendered his familiarity with the texts and imagery of classical,emblematic,and mythographic traditions.Vasari’s composition of images as a compendium of iconography for a decorative program was in the vein of the literary practices of Andrea Alciato(1482-1550),Pierio Valeriano(1477-1558),and Vincenzo Cartari(1531-1590),and followed Paolo Giovio’s advice on how to depict an emblematic image or impresa1(Giovio,1559,p.9).For Giovio(1483-1552),an impresa or badge must contain a figure and motto,its meaning should be clear and precise,the imagery must be pleasant to look at,and the motto must be brief,inventive,and unambiguous.But sometimes Vasari did not follow his advice,relying more on the Renaissance Neoplatonic notion of a concept postulated by the Florentine philosopher Marsilio Ficino(1433-1499).In De vita coelitus comparanda(How Life Should Be Arranged According to the Heavens)2(Ficino,1489;1561-1563;1996,pp.7-19;Kerrigan&Braden,1989,pp.101-115).Ficino discusses the use and the magic potency of images by deliberating on the virtue of imagery,what power pertains to the figure in the Heavens and on Earth,which of the heavenly configurations are impressed on images by the ancients,and how the images are employed in antiquity3(Gombrich,1972,p.172;Chastel,1996,pp.81-89;Moore,1990,p.20,137,181;Bull,2006,pp.7-36).Vasari assimilated these concepts visually in the fresco painting of the Bride with a Rake(1548),located in one of the rooms in his house in Arezzo,the Chamber of Fortune(Chamber of Virtue),where he composed a paradoxical iconographic image-the subject of this essay.This essay is composed of two parts:an introduction to the location of the painting in the Casa Vasari in Arezzo and an iconographical and iconological interpretation of the imagery.
