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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 loca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cavitation
Cavitation is a phenomenon in which the static pressure of a liquid reduces to below the liquid's vapour pressure, leading to the formation of small vapor-filled cavities in the liquid. When subjected to higher pressure, these cavities, called "bubbles" or "voids", collapse and can generate shock waves that may damage machinery. These shock waves are strong when they are very close to the imploded bubble, but rapidly weaken as they propagate away from the implosion. Cavitation is a significant cause of wear in some engineering contexts. Collapsing voids that implode near to a metal surface cause cyclic stress through repeated implosion. This results in surface fatigue of the metal causing a type of wear also called "cavitation". The most common examples of this kind of wear are to pump impellers, and bends where a sudden change in the direction of liquid occurs. Cavitation is usually divided into two classes of behavior: inertial (or transient) cavitation and non-inertial ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VA-111 Shkval
The VA-111 ''Shkval'' (from russian: шквал, ''squall'') torpedo and its descendants are supercavitating torpedoes originally developed by the Soviet Union. They are capable of speeds in excess of 200 knots (370 km/h or 230 miles/h). Design and capabilities Design began in the 1960s when the NII-24 research institute was ordered to produce a new weapon capable of engaging nuclear submarines. The merger of the institute and GSKB-47 created the Research Institute of Applied Hydromechanics, who continued with the design and production of the Shkval. Previously operational as early as 1977, the torpedo was announced as being deployed in the 1990s. The ''Shkval'' is intended as a countermeasure against torpedoes launched by undetected enemy submarines. The VA-111 is launched from torpedo tubes at . A solid-fuel rocket accelerates it to cavitation speed, with a combined-cycle gas turbine in the nose creating the required gas bubble. Once accelerated, speed is maintain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superkavitierender Unterwasserlaufkörper
The Superkavitierender Unterwasserlaufkörper (lit. ''Supercavitating Underwater Running Body,'' formerly known as Barracuda) was a German close-range supercavitating torpedo technology demonstrator designed by the Diehl BGT Defense and developed in cooperation with the German Navy. The supercavitating torpedo for a "close-range defense of underwater targets" was presented to the public in 2005 as a prototype, but it never went into development and procurement. This form of torpedo solves the problem of high underwater drag by means of the supercavitation effect, where underwater at a velocity of around 180 km/h a cavity filled with steam surrounds the moving object. Only the tip is in contact with the water, as such the frictional resistance is greatly reduced. The propulsion of such a torpedo can no longer be done by a propeller but requires a rocket engine. To steer, this torpedo has a pivoting head segment. If the torpedo rises or falls, the water pressure acting on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torpedo
A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, and with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, such a device was called an automotive, automobile, locomotive, or fish torpedo; colloquially a ''fish''. The term ''torpedo'' originally applied to a variety of devices, most of which would today be called mines. From about 1900, ''torpedo'' has been used strictly to designate a self-propelled underwater explosive device. While the 19th-century battleship had evolved primarily with a view to engagements between armored warships with large-caliber guns, the invention and refinement of torpedoes from the 1860s onwards allowed small torpedo boats and other lighter surface vessels, submarines/ submersibles, even improvised fishing boats or frogmen, and later light aircraft, to destroy large ships without the need of large guns, though ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cavitation Number
The Euler number (Eu) is a dimensionless number used in fluid flow calculations. It expresses the relationship between a local pressure drop caused by a restriction and the kinetic energy per volume of the flow, and is used to characterize energy losses in the flow, where a perfect frictionless flow corresponds to an Euler number of 0. The inverse of the Euler number is referred to as the Ruark Number with the symbol Ru. The Euler number is defined as : \mathrm = \dfrac = \dfrac = \frac = \frac where *\rho is the density of the fluid. *p_u is the upstream pressure. *p_d is the downstream pressure. *v is a characteristic velocity of the flow. An alternative definition of the Euler number is given by Shah and Sekulic : \mathrm = \dfrac = \dfrac where * \Delta p is the pressure drop = p_u - p_d Cavitation number The cavitation number has a similar structure, but a different meaning and use: The cavitation number (Ca) is a dimensionle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hoot (torpedo)
The Hoot ( fa, حوت; ''Whale'') is an Iranian supercavitation torpedo claimed to travel at approximately , several times faster than a conventional torpedo. It was claimed to have been successfully test-fired from a surface ship against a dummy submarine during the Iranian military exercise "Great Prophet" () on 2 April 2006 and 3 April 2006. Iran test-fired the torpedo within its territorial waters in the Strait of Hormuz in May 2017. The official Iranian news agency IRNA claims the torpedo was produced and developed by the Islamic Revolutionary Guard Corps (). Most military and industry analysts have concluded that the Hoot is reverse engineered from the Russian VA-111 Shkval supercavitation torpedo which travels at the same speed. See also * List of supercavitating torpedoes A supercavitating torpedo is a torpedo using the effect of supercavitation to create a bubble around the torpedo to move at high velocity under water. The following is a list of supercavitating torpedo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Juliet Marine Systems Ghost
Juliet Marine Systems ''Ghost'' is an advanced super-cavitating stealth ship that can reduce hull friction to 1/900th that of conventional watercraft. It was developed to provide superior protection and capabilities for United States military personnel. It was designed, developed, and built by the private American company Juliet Marine Systems. History Inventor Gregory Sancoff had decided to focus on small watercraft following the attack on USS ''Cole'' in 2000, after which he recalled saying: "Some yahoo terrorists in a cheap little boat and $500 worth of explosives can kill 17 sailors on a billion-dollar ship?" He also came across a 630-page United States Navy report on an exercise called Juliet, where the Navy attacked an enemy force of small, high-speed boats; after two days, the Navy had suffered over 20,000 simulated casualties. Sancoff gathered information on marine technology, including hydroplane racing boats and high-speed super-cavitating torpedoes. In 2007, Sanc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Supercavitating Torpedoes
A supercavitating torpedo is a torpedo using the effect of supercavitation to create a bubble around the torpedo to move at high velocity under water. The following is a list of supercavitating torpedoes which have been developed or are in development. * VA-111 Shkval The VA-111 ''Shkval'' (from russian: шквал, ''squall'') torpedo and its descendants are supercavitating torpedoes originally developed by the Soviet Union. They are capable of speeds in excess of 200 knots (370 km/h or 230 miles/h). ... * Hoot * Superkavitierender Unterwasserlaufkörper (Supercavitating underwater-travelling munition) Barracuda * (Unnamed Prototype) Defense Tech References [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bell AH-1 Cobra
The Bell AH-1 Cobra is a single-engined attack helicopter developed and manufactured by the American rotorcraft manufacturer Bell Helicopter. A member of the prolific Huey family, the AH-1 is also referred to as the HueyCobra or Snake. The AH-1 was rapidly developed as an interim gunship in response to the United States Army's needs in the Vietnam War. It used the same engine, transmission and rotor system of the Bell UH-1 Iroquois, which had already proven itself to be a capable platform during the conflict, but paired it with a redesigned narrow fuselage among other features. The original AH-1, being a dedicated attack helicopter, came equipped with stub wings for various weapons, a chin-mounted gun turret, and an armored tandem cockpit, from which its was operated by a pilot and gunner. Its design was shaped to fulfil a need for a dedicated armed escort for transport helicopter, giving the latter greater survivability in contested environments. On 7 September 1965, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northrop Grumman
Northrop Grumman Corporation is an American multinational aerospace and defense technology company. With 90,000 employees and an annual revenue in excess of $30 billion, it is one of the world's largest weapons manufacturers and military technology providers. The firm ranks on the 2022 ''Fortune'' 500 list of America's largest corporations. Northrop Grumman and its industry partners have won the Collier Trophy eight times, most recently for developing the X-47B, the first unmanned, autonomous air system to operate from an aircraft carrier. Northrop Grumman currently leads the development of the B-21 Raider, a long-range, stealth strategic bomber that can drop conventional and nuclear weapons; it will replace Northrop's own B-2 Spirit, the world's only known stealth bomber. Among its other current projects are development and production of the James Webb Space Telescope, an orbiting observatory launched in 2021, and production of the solid rocket boosters for NASA's Sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iran
Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmenistan to the north, by Afghanistan and Pakistan to the east, and by the Gulf of Oman and the Persian Gulf to the south. It covers an area of , making it the 17th-largest country. Iran has a population of 86 million, making it the 17th-most populous country in the world, and the second-largest in the Middle East. Its largest cities, in descending order, are the capital Tehran, Mashhad, Isfahan, Karaj, Shiraz, and Tabriz. The country is home to one of the world's oldest civilizations, beginning with the formation of the Elamite kingdoms in the fourth millennium BC. It was first unified by the Medes, an ancient Iranian people, in the seventh century BC, and reached its territorial height in the sixth century BC, when Cyrus the Great f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sergey Lavrov
Sergey Viktorovich Lavrov (russian: Сергей Викторович Лавров, ; born 21 March 1950) is a Russian diplomat and politician who has served as the Foreign Minister of Russia since 2004. Lavrov served as the Permanent Representative of Russia to the United Nations from 1994 to 2004. Early life and education Lavrov was born on 21 March 1950 in Moscow, to an Armenian father from Tbilisi, Georgian SSR, and a Russian mother from Noginsk, Russian SFSR. His father's surname was originally Kalantaryan. His mother worked in the Soviet Ministry for Foreign Trade. Lavrov graduated from high school with a silver medal. Since his favorite class was physics, he planned to enter either the National Research Nuclear University or the Moscow Institute of Physics and Technology, but he entered the Moscow State Institute of International Relations (MGIMO) and graduated in 1972. During his education at the MGIMO, Lavrov studied international relations. Soon he learned Sinhal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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