Experimental Investigation of the Influence of Hub Taper Angle on the Performance of Push and Pull Configuration Podded Propellers PDF Download
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Author: Rocky Scott Taylor
Publisher:
ISBN:
Category : Propellers
Languages : en
Pages :
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Book Description
Author: Rocky Scott Taylor
Publisher:
ISBN:
Category : Propellers
Languages : en
Pages : 0
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Book Description
Author: Mohammed Fakhrul Islam
Publisher:
ISBN:
Category : Hydrodynamics
Languages : en
Pages : 272
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Book Description
Author: ALPERTUNGA ANIKER
Publisher: ALPERTUNGA ANIKER
ISBN:
Category : Antiques & Collectibles
Languages : en
Pages : 169
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Book Description
Vessels ftted with azimuthing podded propulsors have much better maneuvering capabilities. They are also environmentally friendly with much reduced exhaust emissions. With these unique features ,they offer signifcant economic, safety and environmental advantages to society, but unfortunately, the routines and the emergency procedures of the azimuthing podded propulsion system were not clearly defned and incorporated into onboard ISM systems. Masters, Chief Engineers and Pilots should receive a specialist training before they lay their hands on the controls, but instead most of them still have to try learning on the job, which sometimes lead to serious incidents, near misses and accidents with serious consequences. One of the reasons that encouraged me to write this book is to draw attention to these serious shortcomings which someday may cause society to pay a high price. My main focus in this book has been on telling about the shiphandling behaviours of electrically-driven azimuthing propulsors rather than the mechanically-driven azimuthing propulsors. Despite the fact that the shiphandling principles of both systems are quite similar, I chose not to mention much about the mechanically driven azimuthing propulsors as they are mostly related with tugboats. Tugboat handling is another speciality, which I believe should be explained only by seasoned tugboat captains themselves. I am a professional maritime pilot but an amateur author and this book is solely intended to share my humble experience and knowledge with my colleagues, ship captains, students and all other interested parties of the maritime industry. Dear Reader, I had actually started writing this book in order to keep my experience on the subject in writing and bring together all the data I have collected from various resources at different times. To improve my knowledge and experience, I have also joined a special manned model course for “Pod Handling and Emergencies” at Port Revel Shiphandling Centre which is located at Grenoble, France in May 2010. Vessels ftted with azimuthing podded propulsors have much better manoeuvring capabilities, such as reduced turning diameters and signifcantly shorter stopping distances compared to the conventional systems with a fxed propeller and conventional rudder. They are also environmentally friendly with much reduced exhaust emissions. With these unique features ,they offer signifcant economic, safety and environmental advantages to society, but unfortunately, the routines and the emergency procedures of the azimuthing podded propulsion system were not clearly defned and incorporated into onboard ISM systems. Even class surveyors and Port State surveyors don’t seem to have enough knowledge about this technology. Masters, Chief Engineers and Pilots should receive a specialist training before they lay their hands on the controls, but instead most of them still have to try learning on the job, which sometimes lead to serious incidents, near misses and accidents with serious consequences. One of the reasons that encouraged me to write this book is to draw attention to these serious shortcomings which someday may cause society to pay a high price.
Author: Roy S. Rice
Publisher:
ISBN:
Category : Propellers
Languages : en
Pages : 92
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Author: United States. National Advisory Committee for Aeronautics
Publisher:
ISBN:
Category : Aerofoils
Languages : en
Pages : 218
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Book Description
Author: William Frederick Durand
Publisher:
ISBN:
Category : Propellers
Languages : en
Pages : 84
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Book Description
Author: James Andrew MacNeill
Publisher:
ISBN:
Category : Propellers
Languages : en
Pages : 1058
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Book Description
Author: Jielong Cai
Publisher:
ISBN:
Category :
Languages : en
Pages : 77
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Book Description
With the increased usage of propeller-driven unmanned-aerial-vehicles (UAV) in closed spaces such as caves, buildings, pipelines, etc. for photography, surveillance, and inspection, understanding the influence of the ground and ceiling on a remote-controlled (R/C) propeller is of the utmost importance. The flying characteristics of drones changes when an object or a ground plane is in its close proximity due to changes in its propeller performance. The changes in performance are due to the changes in the flow field around the propeller that occur due to ground proximity, which is also known as ground effect. Ground effect on lifting rotor performance has been studied theoretically and experimentally for decades. Historically, most investigations focus on helicopter rotors, which have high aspect ratio, lower pitch and rarely have spanwise twist. This research focuses on smaller size rotors, in particular, the thin-electric propeller which is used widely on small UAVs. The research considers parameter variations not broadly available in the literature such as propeller pitch, diameter, solidity, and blockage. In particular, extreme ground effect is considered, where the ratio of ground plane stand-off distance to propeller diameter is 0.1 or less. Moreover, the propeller is reversed, to examine the ceiling effect. Typically, the ground effect investigation is done with a ground plane that is big enough to be considered an infinite plane. In this research, both infinite plane and circular plates of similar diameter (or less) of the propeller are used as ground planes. Various circular plates with different diameter to propeller diameter ratios are used in the research representing different 'blockage ratios'. The investigation gives insight into changes in propeller performance in proximity to fuselages of a given diameter in propeller-driven airplanes under pusher and puller configurations. All experiments were conducted on a thrust-stand built in-house at the University of Dayton Low-Speed Wind Tunnel (UD-LSWT) Laboratory. All propellers used in the experiment are from the "thin electric" APC series, with diameter ranging from 11 inches to 17 inches and pitch from 4.5 inches to 14 inches. The propeller peak Reynolds number varies from 90,000 to 190,000 in the experiment. Circular plates with diameter ratio from 0.5 to 1.0 are used in the blockage effect experiment. Force, torque and RPM propeller data are taken during the experiment from a propeller diameter normalized ground distance of -1.5 to 1.5. Results from the infinite ground experiment are separated into three major sections: thrust coefficient and power coefficient, power required at constant thrust, and effective thrust. A significant increment in the thrust coefficient and decrement in the power coefficient is found in ground proximity among the propellers with a pitch-to-diameter ratio less than 0.7. This results in a decrement of power required at constant thrust in ground effect. Almost identical changes in the power required at constant thrust in the ceiling effect is also found in most of the low pitch to diameter ratio propellers. For the blockage experiment, a less significant reduction in the power required in constant thrust for all propellers is found at lower blockage ratios as expected. Similar trends in the effect on? thrust for different propellers at the same blockage ratio are found. Results for the positive h/D region (the puller configuration), overlap regardless of the propeller pitch to diameter ratio or solidity. A phenomenological expression (an algebraic equation) for power required at constant thrust as a function of propeller parameter is established during the research to predict the changes in the propeller performance in ground effect which will benefit the operation of small UAVs in both open and confined areas.
Author: K. D. Korkan
Publisher:
ISBN:
Category :
Languages : en
Pages : 20
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Author: Joe F Thompson (Jr)
Publisher:
ISBN:
Category :
Languages : en
Pages : 95
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Book Description
Experimental evidence of the existence of a stagnation line between the leading and trailing edges on the outer surface of the shroud of a shrouded propeller in the static condition, in rearward motion, and in forward motion is presented. This stagnation line on the outer surface, which is a result of viscous interaction between the propeller slipstream and the external flow, causes a reduction in shroud circulation below that calculated by distributed singularities methods which assume a stagnation line at the trailing edge only. Shroud thrust decreases as the distance between this stagnation line and the trailing edge increases. It is shown that in rearward motion, such as is the case for a VTOL aircraft landing, the stagnation line moves forward from the vicinity of the trailing edge to the vicinity of the leading edge as vehicle speed increases. This forward movement of the stagnation line results in a significant loss in thrust, which can be correlated with the stagnation line location. Shroud pressure distribution, stagnation line location, and shroud thrust are presented for all three cases of motion at several propeller pitch angles, propeller rotational speeds, and vehicle linear speeds. It is shown that the flow pattern about the shroud is rather complicated in rearward motion, involving two coaxial ring-vortices surrounding the shroud. (Author).
