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Supercavitating Propeller
{{no footnotes, date=November 2016 The supercavitating propeller is a variant of a propeller for propulsion in water, where supercavitation is actively employed to gain increased speed by reducing friction. They are being used for military purposes and for high performance racing boats as well as model racing boats. This article distinguishes a supercavitating propeller from a subcavitating propeller running under supercavitating conditions. In general, subcavitating propellers become less efficient when they are running under supercavitating conditions. The supercavitating propeller operates submerged with the entire diameter of the blade below the water line. Its blades are wedge-shaped to force cavitation at the leading edge and to avoid water skin friction along the whole forward face. As the cavity collapses well behind the blade, the supercavitating propeller avoids the spalling damage due to cavitation that is a problem with conventional propellers. An alternative to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Super Cavitating
Super may refer to: Computing * SUPER (computer program), or Simplified Universal Player Encoder & Renderer, a video converter / player * Super (computer science), a keyword in object-oriented programming languages * Super key (keyboard button) Film and television * ''Super'' (2005 film), a Telugu film starring Nagarjuna, Anushka Shetty and Ayesha Takia * ''Super'' (2010 Indian film), a Kannada language film starring Upendra and Nayantara * ''Super'' (2010 American film), a film written and directed by James Gunn, and starring Rainn Wilson and Elliot Page * "Super" (''Person of Interest''), an episode of the TV series ''Person of Interest'' Music * "Super" (Cordae song), a 2021 song by American rapper Cordae * "Super" (Neu! song), a 1972 song by German band Neu! * " Super (1, 2, 3)", a 2000 song by Italian DJ Gigi D'Agostino * ''Super'' (album), a 2016 album by Pet Shop Boys Other uses * Super!, an Italian television network * Super (gamer) (born 2000), America ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Propeller
A propeller (colloquially 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 specially 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 sculling. In sculling, a single blade is moved through an arc, from side to side taking care to keep presenting the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supercavitation
Supercavitation is the use of a cavitation bubble to reduce skin friction drag on a submerged object and enable high speeds. Applications include torpedoes and propellers, but in theory, the technique could be extended to an entire underwater vessel. Physical principle Cavitation is the formation of vapour bubbles in liquid caused by flow around an object. Bubbles form when water accelerates around sharp corners and the pressure drops below the vapour pressure. Pressure increases upon deceleration, and the water generally reabsorbs the vapour; however, vapour bubbles can implode and apply small concentrated impulses that may damage surfaces like ship propellers and pump impellers. The potential for vapour bubbles to form in a liquid is given by the nondimensional cavitation number. It equals local pressure minus vapour pressure, divided by dynamic pressure. At increasing depths (or pressures in piping), the potential for cavitation is lower because the difference between local ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Go-fast Boat
A go-fast boat is a small, fast power boat designed with a long narrow platform and a planing hull. During the United States alcohol prohibition era, these boats were used in " rum-running", transferring illegal liquor from larger vessels waiting outside US territorial waters to the mainland. Their high speed enabled them to avoid interception by the law enforcement. The present conception of such boats is based largely on designs by Donald Aronow for offshore powerboat racing in the 1960s. During this period, these boats were also used by drug smugglers to transfer drugs across the Caribbean to the United States. Name Go-fast boats are also called "cigarette boats" and "cigar boats"—references to their shape, though some report that they are references to items they were used to smuggle. "Cigarette boat" is especially popular because it is a brand name for a line of go-fast boats that popularized and largely defined the class in the 1960s, made by Don Aronow's Cigarette ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parasitic Drag
Parasitic drag, also known as profile drag, is a type of aerodynamic drag that acts on any object when the object is moving through a fluid. Parasitic drag is a combination of form drag and skin friction drag. It affects all objects regardless of whether they are capable of generating lift. Total drag on an aircraft is made up of parasitic drag and lift-induced drag. Parasitic drag comprises all types of drag except lift-induced drag. Form drag Form drag arises because of the shape of the object. The general size and shape of the body are the most important factors in form drag; bodies with a larger presented cross-section will have a higher drag than thinner bodies; sleek ("streamlined") objects have lower form drag. Form drag follows the drag equation, meaning that it increases with the square of the velocity, and thus becomes more important for high-speed aircraft. Form drag depends on the longitudinal section of the body. A prudent choice of body profile is essential for a lo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spall
Spall are fragments of a material that are broken off a larger solid body. It can be produced by a variety of mechanisms, including as a result of projectile impact, corrosion, weathering, cavitation, or excessive rolling pressure (as in a ball bearing). Spalling and spallation both describe the process of surface failure in which spall is shed. The terms ''spall'', ''spalling'', and ''spallation'' have been adopted by particle physicists; in neutron scattering instruments, neutrons are generated by bombarding a uranium (or other) target with a stream of atoms. The neutrons that are ejected from the target are known as "spall". Mechanical spalling Mechanical spalling occurs at high stress contact points, for example, in a ball bearing. Spalling occurs in preference to brinelling where the maximal shear stress occurs not at the surface, but just below, shearing the spall off. One of the simplest forms of mechanical spalling is plate impact, in which two waves of compression ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Propeller
A propeller (colloquially 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 specially 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 sculling. In sculling, a single blade is moved through an arc, from side to side taking care to keep presenting the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entrainment (engineering)
:''See entrainment for other types.'' In engineering, entrainment is the entrapment of one substance by another substance. For example: * The entrapment of liquid droplets or solid particulates in a flowing gas, as with smoke. * The entrapment of gas bubbles or solid particulates in a flowing liquid, as with aeration. * Given two mutually insoluble liquids, the emulsion of droplets of one liquid into the other liquid, as with margarine. * Given two gases, the entrapment of one gas into the other gas. * "Air entrainment" - The intentional entrapment of air bubbles into concrete. * Entrainment defect An entrainment defect is a term used in metallurgy to describe a defect created in a casting by the folding-over of the oxidized surface layer of the molten metal into the bulk liquid. Outside of special cases, the surface of a molten metal is cov ... in metallurgy, as a result of folded pockets of oxide inside the melt. See also * Souders-Brown equation References Chemical engi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vosper & Company
Vosper & Company, often referred to simply as Vospers, was a British shipbuilding company based in Portsmouth, England. History The Company was established in 1871 by Herbert Edward Vosper, concentrating on ship repair and refitting work. By the turn of the century, Vosper was prospering as a general-purpose builder of small craft, boilers and marine engines, for which they had made a name for themselves as a producer of reliable designs. In the lean times after World War I, they concentrated mainly on ship repair to survive. By the early 1930s, the company began to concentrate on high speed naval craft, yachts and power boats, for which they would become renowned. In 1936 they became listed as a public company, known as Vosper, Limited, at which time they moved to a new yard at Portchester. They built Sir Malcolm Campbell's Water speed record, water speed record breaking ''Bluebird K4'', reaching 141.74 mph in 1939. Vosper would become famous as the builder of small (60 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hickman Sea Sled
The Hickman Sea Sled is an inverted vee planing hull invented by Albert Hickman. The Sea Sled is a direct forerunner of the modern high speed catamaran or tunnel hull. The reduced friction is due to a "trapped" gas film between the hull surface and water. A similar effect is seen in super-cavitating torpedoes where a gas generator creates a film separation to water friction. "A new type of vessel, which promises to revolutionize water craft and which takes the same place on the water that the automobile does on land" - ''Scientific American'' 26 September 1914 See also * Cathedral hull * Boston Whaler Boston Whaler is an American boat manufacturer. It is a subsidiary of the Brunswick Boat Group, a division of the Brunswick Corporation. Boston Whalers were originally produced in Massachusetts, hence the name, but today are manufactured in Edge ... * Supercavitation propeller References * Campbell, Lorne''Innovation in Small Craft Design - A Tribute'' The Royal Institute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axial Fan Design
An axial fan is a type of fan that causes gas to flow through it in an axial direction, parallel to the shaft about which the blades rotate. The flow is axial at entry and exit. The fan is designed to produce a pressure difference, and hence force, to cause a flow through the fan. Factors which determine the performance of the fan include the number and shape of the blades. Fans have many applications including in wind tunnels and cooling towers. Design parameters include power, flow rate, pressure rise and efficiency. Axial fans generally comprise fewer blades (two to six) than ducted fans. Axial fans commonly have larger radius and lower speed (ω) than ducted fans (esp. at similar power. Stress proportional to r^2). Calculation of parameters Since the calculation cannot be done using the inlet and outlet velocity triangles, which is not the case in other turbomachines, calculation is done by considering a mean velocity triangle for flow only through an infinitesimal blad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boston Whaler
Boston Whaler is an American boat manufacturer. It is a subsidiary of the Brunswick Boat Group, a division of the Brunswick Corporation. Boston Whalers were originally produced in Massachusetts, hence the name, but today are manufactured in Edgewater, Florida. History Richard "Dick" Fisher graduated from Harvard University in 1936. He ran a company building small, lightweight boats out of balsa wood. He designed a rowboat and got the materials to build it, but he never completed it. In the 1950s, polyurethane foam, a stiff, lightweight, buoyant material, was invented. Fisher imagined it as a replacement for the lightweight balsa used in small boat construction, and in 1954 he constructed a small sailing dinghy filled with the foam, with a design similar to the Sunfish. He showed the finished product to his friend, naval architect C. Raymond Hunt. Hunt recognized potential in the process, however he did not feel the design was particularly suited to sailboats. Instead, he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
