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Ducted Propeller
A ducted propeller, also known as a Kort nozzle, is a marine propeller shrouded with a non-rotating nozzle. It is used to improve the efficiency of the propeller and is especially used on heavily loaded propellers or propellers with limited diameter. It was developed first by Luigi Stipa (1931) and later by Ludwig Kort (1934). The cross-section of the shroud has the form of a foil, and the shroud can offer hydrodynamic advantages over bare propellers, under certain conditions. Advantages are increased efficiency at lower speeds (10 knots), course stability when sailing astern, and increase of cavitation. Ducted propellers are also used to replace rudders. History Luigi Stipa in 1931 and later Ludwig Kort (1934) demonstrated that an increase in propulsive efficiency could be achieved by surrounding the propeller with a foil-shaped shroud in the case of heavily loaded propellers. A "Kort Nozzle" is referred to as an accelerating nozzle and is generally a MARIN 19A profile o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bel Vis 346
Bel can mean: Mythology * Belenus or Bel, a Celtic deity * Bel (mythology), a title (meaning "lord" or "master") for various gods in Babylonian religion People * Bel (name) * Annabel Linquist, known as Bel, American artist, musician, and entrepreneur Places * Bél, the Hungarian name for Beliu Commune, Arad County, Romania * Bel Mountain, in the Zagros Mountains of western and southwestern Iran * Bel, Iran (other) * Bel, Osh, village in Osh Region, Kyrgyzstan * Bel, Syria, village in Aleppo Governorate * Temple of Bel in Palmyra, Syria Languages * Bel languages, spoken in northern Papua New Guinea * ISO 639 code for the Belarusian language Other uses * Groupe Bel, a France-based multinational cheese distributor * Bel (unit), a unit of gain or loss equal to ten decibels See also * BEL (other) * Bell (other) * Belle (other) Belle may refer to: People and fictional characters * Belle (given name), a list of people and fictional cha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bottom Suction
Bottom may refer to: Anatomy and sex * Bottom (BDSM), the partner in a BDSM who takes the passive, receiving, or obedient role, to that of the top or dominant * Bottom (sex), a term used by gay couples and BDSM * Buttocks or bottom, part of the anatomy on the posterior of the pelvic region of apes and humans, and many other bipeds or quadrupeds Arts, entertainment, and media * ''Bottom'' (TV series), a British sitcom and stage show * "Bottom", a song by Puddle of Mudd from '' Life on Display'' * "Bottom", a song by Tool from '' Undertow'' * ''Bottom'', a 2011 film by Todd Verow * Nick Bottom, a character from Shakespeare's ''A Midsummer Night's Dream'' * ''The Bottoms'' (novel), a 2000 novel by Joe R. Lansdale * ''Bottoms'', a 1966 film by Yoko Ono * ''Bottoms'' (film), a 2023 film by Emma Seligman Geography * Bottom (valley), the floor of a valley ** List of geographical bottoms, list of geographical features called "bottom" * Bottomland (freshwater ecology), low ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Propellers
A propeller (often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon a working fluid such as water or air. Propellers are used to pump fluid through a pipe or duct, or to create thrust to propel a boat through water or an aircraft through air. The blades are shaped so that their rotational motion through the fluid causes a pressure difference between the two surfaces of the blade by Bernoulli's principle which exerts force on the fluid. Most marine propellers are screw propellers with helical blades rotating on a propeller shaft (ship), propeller shaft with an approximately horizontal axis. History Early developments The principle employed in using a screw propeller is derived from stern sculling. In sculling, a single blade is moved through an arc, from side to side taking care to keep presenting the blade to the wat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bollard Pull
Bollard pull is a conventional measure of the pulling (or towing) power of a watercraft. It is defined as the force (usually in tonnes-force or kilonewtons (kN)) exerted by a vessel under full power, on a shore-mounted bollard through a tow-line, commonly measured in a practical test (but sometimes simulated) under test conditions that include calm water, no tide, level trim, and sufficient depth and side clearance for a free propeller stream. Like the horsepower or mileage rating of a car, it is a convenient but idealized number that must be adjusted for operating conditions that differ from the test. The bollard pull of a vessel may be reported as two numbers, the ''static'' or ''maximum'' bollard pull – the highest force measured – and the ''steady'' or ''continuous'' bollard pull, the average of measurements over an interval of, for example, 10 minutes. An equivalent measurement on land is known as drawbar pull, or tractive force, which is used to measure the total hori ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circulation Around Nozzles
Circulation may refer to: Science and technology * Atmospheric circulation, the large-scale movement of air * Circulation (physics), the path integral of the fluid velocity around a closed curve in a fluid flow field * Circulatory system, a biological organ system whose primary function is to move substances to and from cells * Circulation problem, a generalization of network flow problems * Circulation (architecture), the flow of people through a building * Circulation (currency), all currency held by consumers and businesses, but not by financial institutions and governments * Exhaust gas recirculation, a nitrogen oxide reduction technique used in most gasoline and diesel engines * Library circulation, the activities around the lending of library books and other material to users of a lending library * Ocean circulation, the large-scale movement of water * Rhetorical circulation, the ways that texts and discourses move through time and space Other uses * Print circulation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NACA Airfoil
The NACA airfoil series is a set of standardized airfoil shapes developed by this agency, which became widely used in the design of aircraft wings. Origins NACA initially developed the numbered airfoil system which was further refined by the United States Air Force at Langley Research Center. According to the NASA website: Four-digit series The NACA four-digit wing sections define the profile by: # First digit describing maximum Camber (aerodynamics), camber as percentage of the Chord (aircraft), chord. # Second digit describing the distance of maximum camber from the airfoil leading edge in tenths of the chord. # Last two digits describing maximum thickness of the airfoil as percent of the chord. For example, the NACA 2412 airfoil has a maximum camber of 2% located 40% (0.4 chords) from the leading edge with a maximum thickness of 12% of the chord. The NACA 0015 airfoil is symmetrical, the 00 indicating that it has no camber. The 15 indicates that the airfoil has a 15% thick ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maritime Research Institute Netherlands
MARIN, the Maritime Research Institute Netherlands, is the leading institute in the world for hydrodynamic research and maritime technology. The services incorporate a unique combination of simulation, model testing, full-scale measurements and training programmes. MARIN provides services to the shipbuilding and Offshore construction, offshore industry and governments. Customers include commercial ship builders, fleet owners, naval architects, classification societies, oil and LNG companies and navies all over the world. In the Netherlands MARIN has the status of Great Technological Institute, thus linking science and applied knowledge. Results from fundamental research are directly integrated in applications for clients. Over 85% of the turnover is realised by commercial projects for the international maritime industry. The remaining 15% is derived from scientific research. Offices MARIN’s head office is in Wageningen, with additional offices in Ede, Netherlands, Ede, Houston, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NACA 4415 (duct Profile)
The NACA airfoil series is a set of standardized airfoil shapes developed by this agency, which became widely used in the design of aircraft wings. Origins NACA initially developed the numbered airfoil system which was further refined by the United States Air Force at Langley Research Center. According to the NASA website: Four-digit series The NACA four-digit wing sections define the profile by: # First digit describing maximum camber as percentage of the chord. # Second digit describing the distance of maximum camber from the airfoil leading edge in tenths of the chord. # Last two digits describing maximum thickness of the airfoil as percent of the chord. For example, the NACA 2412 airfoil has a maximum camber of 2% located 40% (0.4 chords) from the leading edge with a maximum thickness of 12% of the chord. The NACA 0015 airfoil is symmetrical, the 00 indicating that it has no camber. The 15 indicates that the airfoil has a 15% thickness to chord length ratio: it is 15% a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pump-jet
A pump-jet, hydrojet, or water jet is a marine system that produces a jet of water for propulsion. The mechanical arrangement may be a ducted propeller (axial-flow pump), a centrifugal pump, or a mixed flow pump which is a combination of both centrifugal and axial designs. The design also incorporates an intake to provide water to the pump and a nozzle to direct the flow of water out of the pump. Design A pump-jet works by having an intake (usually at the bottom of the hull) that allows water to pass underneath the vessel into the engines. Water enters the pump through this inlet. The pump can be of a centrifugal design for high speeds, or an axial flow pump for low to medium speeds. The water pressure inside the inlet is increased by the pump and forced backwards through a nozzle. With the use of a ''reversing bucket'', reverse thrust can also be achieved for faring backwards, quickly and without the need to change gear or adjust engine thrust. The reversing bucket ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airfoil
An airfoil (American English) or aerofoil (British English) is a streamlined body that is capable of generating significantly more Lift (force), lift than Drag (physics), drag. Wings, sails and propeller blades are examples of airfoils. Foil (fluid mechanics), Foils of similar function designed with water as the working fluid are called hydrofoils. When oriented at a suitable angle, a solid body moving through a fluid deflects the oncoming fluid (for fixed-wing aircraft, a downward force), resulting in a force on the airfoil in the direction opposite to the deflection. This force is known as aerodynamic force and can be resolved into two components: lift (perpendicular to the remote freestream velocity) and drag (Parallel (geometry), parallel to the freestream velocity). The lift on an airfoil is primarily the result of its angle of attack. Most foil shapes require a positive angle of attack to generate lift, but Camber (aerodynamics), cambered airfoils can generate lift at zero ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Knot (unit)
The knot () is a unit of speed equal to one nautical mile per hour, exactly (approximately or ). The ISO standard symbol for the knot is kn. The same symbol is preferred by the Institute of Electrical and Electronics Engineers ( IEEE), while kt is also common, especially in aviation, where it is the form recommended by the International Civil Aviation Organization ( ICAO). The knot is a non- SI unit. The knot is used in meteorology, and in maritime and air navigation. A vessel travelling at 1 knot along a meridian travels approximately one minute of geographic latitude in one hour. Definitions ;1 international knot = :1 nautical mile per hour (by definition), : (exactly), : (approximately), : (approximately), : (approximately) : (approximately). The length of the internationally agreed nautical mile is . The US adopted the international definition in 1954, having previously used the US nautical mile (). The UK adopted the international nautical mile defi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
