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Schnuerle Porting
Schnuerle porting is a system to improve efficiency of a valveless two-stroke engine by giving better scavenging. The intake and exhaust ports cut in the cylinder wall are shaped to give a more efficient transfer of intake and exhaust gases. Description Gas flow within the two-stroke engine is even more critical than for a four-stroke engine, as the two flows are both entering and leaving the combustion chamber simultaneously. A well-defined flow pattern is required, avoiding any turbulent mixing. The efficiency of the two-stroke engine depends on effective scavenging, the more complete replacement of the old spent charge with a fresh charge. Apart from large diesels with separate superchargers, two-stroke engines are generally piston-ported and use their crankcase beneath the piston for the compression needed to fill the cylinder with fuel/air mixture. The cylinder has a transfer port (inlet from crankcase to cylinder) and an exhaust port cut into it. These are opened, as the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Newnes (publisher)
George Newnes Ltd is a British publisher. The company was founded in 1891 by George Newnes (1851–1910), considered a founding father of popular journalism. Newnes published such magazines and periodicals as ''Tit-Bits'', ''The Wide World Magazine'', '' The Captain'', ''The Strand Magazine'', ''The Grand Magazine'', ''John O'London's Weekly'', '' Sunny Stories for Little Folk'', ''Woman's Own'', and the ''"Practical"'' line of magazines overseen by editor Frederick J. Camm. Long after the founder's death, Newnes was known for publishing ground-breaking consumer magazines such as ''Nova''. Newnes published books by such authors as Enid Blyton, Hall Caine, Richmal Crompton, Sir Arthur Conan Doyle, George Goodchild, W. E. Johns, P. G. Wodehouse, and John Wyndham. Initially an independent publisher, Newnes became an imprint of the International Publishing Company in 1961. Today, books under the Newnes imprint continue to be published by Elsevier. History Origins Founder George ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two-stroke Engine
A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a power cycle with two strokes (up and down movements) of the piston during one power cycle, this power cycle being completed in one revolution of the crankshaft. A four-stroke engine requires four strokes of the piston to complete a power cycle during two crankshaft revolutions. In a two-stroke engine, the end of the combustion stroke and the beginning of the compression stroke happen simultaneously, with the intake and exhaust (or scavenging) functions occurring at the same time. Two-stroke engines often have a high power-to-weight ratio, power being available in a narrow range of rotational speeds called the power band. Two-stroke engines have fewer moving parts than four-stroke engines. History The first commercial two-stroke engine involving cylinder compression is attributed to Scottish engineer Dugald Clerk, who patented his design in 1881. However, unlike most later two-s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scavenging (automotive)
Scavenging is the process of replacing the exhaust gas in a cylinder of an internal combustion engine with the fresh air/fuel mixture (or fresh air, in the case of direct-injection engines) for the next cycle. If scavenging is incomplete, the remaining exhaust gases can cause improper combustion for the next cycle, leading to reduced power output. Scavenging is equally important for both two-stroke and four-stroke engines. Most modern four-stroke engines use crossflow cylinder heads and valve timing overlap to scavenge the cylinders. Modern two-stroke engines use either Schnuerle scavenging (also known as "loop scavenging") or uniflow scavenging. The scavenge or scavenging port refers to that port through which clean air enters the cylinder, the exhaust port through which it leaves. Origins The first engines deliberately designed to encourage scavenging were gas engines built by Crossley Brothers Ltd in the United Kingdom in the early 1890s. These ''Crossley Otto Scavengin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cylinder (engine)
In a reciprocating engine, the cylinder is the space in which a piston travels. The inner surface of the cylinder is formed from either a thin metallic liner (also called "sleeve") or a surface coating applied to the engine block. A piston is seated inside each cylinder by several metal piston rings, which also provide seals for compression and the lubricating oil. The piston rings do not actually touch the cylinder walls, instead they ride on a thin layer of lubricating oil. Steam engines The cylinder in a steam engine is made pressure-tight with end covers and a piston; a valve distributes the steam to the ends of the cylinder. Cylinders were cast in cast iron and later in steel. The cylinder casting can include other features such as valve ports and mounting feet. Internal combustion engines The cylinder is the space through which the piston travels, propelled to the energy generated from the combustion of the air/fuel mixture in the combustion chamber. In an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Revers Scavenging
A revers or rever is a part of a garment that is reversed to display the lining or facing outside. The word is borrowed from French ''revers'', which is reflected in the final ''s'' being silent. The most common form of revers is the lapel. The revers emerged in the 1860s in France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ... as soldiers began unbuttoning the fronts of their uniforms. When the revers became dirty, the uniform could be buttoned up to show a clean front again. References {{Clothing materials and parts Parts of clothing Neckwear nl:Revers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Four-stroke Engine
A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either direction. The four separate strokes are termed: #Intake: Also known as induction or suction. This stroke of the piston begins at top dead center (T.D.C.) and ends at bottom dead center (B.D.C.). In this stroke the intake valve must be in the open position while the piston pulls an air-fuel mixture into the cylinder by producing vacuum pressure into the cylinder through its downward motion. The piston is moving down as air is being sucked in by the downward motion against the piston. #Compression: This stroke begins at B.D.C, or just at the end of the suction stroke, and ends at T.D.C. In this stroke the piston compresses the air-fuel mixture in preparation for ignition during the power stroke (below). Both the intake and exhaust valves are close ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turbulence
In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between those layers. Turbulence is commonly observed in everyday phenomena such as surf, fast flowing rivers, billowing storm clouds, or smoke from a chimney, and most fluid flows occurring in nature or created in engineering applications are turbulent. Turbulence is caused by excessive kinetic energy in parts of a fluid flow, which overcomes the damping effect of the fluid's viscosity. For this reason turbulence is commonly realized in low viscosity fluids. In general terms, in turbulent flow, unsteady vortices appear of many sizes which interact with each other, consequently drag due to friction effects increases. This increases the energy needed to pump fluid through a pipe. The onset of turbulence can be predicted by the dimensionless Rey ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two-stroke Diesel Engine
A two-stroke diesel engine is an internal combustion engine that uses compression ignition, with a two-stroke combustion cycle. It was invented by Hugo Güldner in 1899.Mau (1984) p.7 In compression ignition, air is first compressed and heated; fuel is then injected into the cylinder, causing it to self-ignite. The two-stroke cycle ignites the fuel to deliver a power stroke each time the piston rises and falls in the cylinder, without any need for the additional exhaust and induction strokes of the four-stroke cycle. History According to the designer of the first operational diesel engine, Imanuel Lauster, Rudolf Diesel did not originally intend using the two-stroke principle for the diesel engine. Hugo Güldner designed what is believed to be the first operational two-stroke diesel engine in 1899, and he convinced MAN, Krupp and Diesel to fund building this engine with ℳ 10,000 each. Güldner's engine had a 175 mm work cylinder, and a 185 mm scavenging cylinder ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supercharger
In an internal combustion engine, a supercharger compresses the intake gas, forcing more air into the engine in order to produce more power for a given displacement. The current categorisation is that a supercharger is a form of forced induction that is mechanically powered (usually by a belt from the engine's crankshaft), as opposed to a turbocharger, which is powered by the kinetic energy of the exhaust gasses. However, up until the mid-20th century, a turbocharger was called a "turbosupercharger" and was considered a type of supercharger. The first supercharged engine was built in 1878, with usage in aircraft engines beginning in the 1910s and usage in car engines beginning in the 1920s. In piston engines used by aircraft, supercharging was often used to compensate for the lower air density at high altitudes. Supercharging is less commonly used in the 21st century, as manufacturers have shifted to turbochargers to reduce fuel consumption and/or increase power outputs. Des ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cross Scavenging
Scavenging is the process of replacing the exhaust gas in a cylinder of an internal combustion engine with the fresh air/fuel mixture (or fresh air, in the case of direct-injection engines) for the next cycle. If scavenging is incomplete, the remaining exhaust gases can cause improper combustion for the next cycle, leading to reduced power output. Scavenging is equally important for both two-stroke and four-stroke engines. Most modern four-stroke engines use crossflow cylinder heads and valve timing overlap to scavenge the cylinders. Modern two-stroke engines use either Schnuerle scavenging (also known as "loop scavenging") or uniflow scavenging. The scavenge or scavenging port refers to that port through which clean air enters the cylinder, the exhaust port through which it leaves. Origins The first engines deliberately designed to encourage scavenging were gas engines built by Crossley Brothers Ltd in the United Kingdom in the early 1890s. These ''Crossley Otto Scavengin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deflector Piston
A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder. In some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder. __TOC__ Piston engines Internal combustion engines An internal combustion engine is acted upon by the pressure of the expanding combustion gases in the combustion chamber space at the top of the cylinder. This force then acts downwards through the connecting rod and onto the crankshaft. The connecting rod is attached ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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