Mechanical fan - Wikipedia. This article is about mechanical fans. For other uses, see Fan. The rotating assembly of blades and hub is known as an impeller, a rotor, or a runner. Usually, it is contained within some form of housing or case. Omaha Street Railway History - 1909 Newspaper. THE FIRST ELECTRIC RAILWAYS. They have one servant. Source: Douglas Lammings' An English Football Internationalist Who's Who. Overview of The Electric Servant, 1910, directed by Walter R. Booth, with at Turner Classic Movies. Most fans are powered by electric motors, but other sources of power may be used, including hydraulic motors and internal combustion engines. Fans produce flows with high volume and low pressure (although higher than ambient pressure), as opposed to compressors which produce high pressures at a comparatively low volume. A fan blade will often rotate when exposed to a fluid stream, and devices that take advantage of this, such as anemometers and wind turbines, often have designs similar to that of a fan. Typical applications include climate control and personal thermal comfort (e. While fans are often used to cool people, they do not actually cool air (if anything, electric fans warm it slightly due to the warming of their motors), but work by evaporative cooling of sweat and increased heat convection into the surrounding air due to the airflow from the fans. Thus, fans may become ineffective at cooling the body if the surrounding air is near body temperature and contains high humidity. Etymology. It was a handheld fan made from bamboo strips or other plant fibre, that could be rotated or fanned to move air. The Electric Servant - 1909 was released on: UK: September 1909 USA.Curator Peter Morris shares nine unusual facts about the Science Museum to celebrate our 105 th birthday today (26 June 1909). Some scenes in the Ipcress File, the. 1909 Detroit businessman Fred Wardell. Ohio department store, invented the first portable electric vacuum cleaner. During British rule, the word came to be used by Anglo- Indians to mean a large swinging flat fan, fixed to the ceiling, and pulled by a servant, called the punkawallah. For purposes of air conditioning, the Han Dynasty craftsman and engineer Ding Huan (fl. CE) invented a manually operated rotary fan with seven wheels that measured 3 m (1. Tang Dynasty (6. 18. The English architect Sir Christopher Wren applied an early ventilation system in the Houses of Parliament that used bellows to circulate air. Wren's design would be the catalyst for much later improvement and innovation. The first rotary fan used in Europe was for mine ventilation during the 1. Georg Agricola (1. The civil engineer John Smeaton, and later John Buddle installed reciprocating air pumps in the mines in the North of England. However, this arrangement was not ideal as the machinery was liable to breaking down. With the advent of practical steam power, fans could finally be used for ventilation. David Boswell Reid, a Scottish physician, installed four steam powered fans in the ceiling of St George's Hospital in Liverpool, so that the pressure produced by the fans would force the incoming air upward and through vents in the ceiling. The model was exhibited at the Great Exhibition of 1. Improvements in the technology were made by James Nasmyth, Frenchman Theophile Guibal and J. In 1. 88. 2, Philip Diehl introduced the electric ceiling fan. During this intense period of innovation, fans powered by alcohol, oil, or kerosene were common around the turn of the 2. In 1. 90. 9, KDK pioneered the invention of mass- produced electric fans for home use. In the 1. 92. 0s, industrial advances allowed steel fans to be mass- produced in different shapes, bringing fan prices down and allowing more homeowners to afford them. In the 1. 93. 0s, the first art deco fan (the . By the 1. 95. 0s, fans were manufactured in colors that were bright and eye catching. Window and central air conditioning in the 1. Boyd invented the HVLS ceiling fan. It was a slow moving fan with an eight- foot diameter. Due to its size, the fan moved a large column of air and continuously mixed fresh air with the stale air inside. They are used in many industrial and agricultural settings, because of their energy efficiency. They are used on the floor, table, desk, or hung from the ceiling. They can also be built into a window, wall, roof, chimney, etc. Most electronic systems such as computers include fans to cool circuits inside, and in appliances such as hair dryers and portable space heaters and mounted/installed wall heaters. They are also used for moving air in air- conditioning systems, and in automotive engines, where they are driven by belts or by direct motor. Fans used for comfort create a wind chill by increasing the heat transfer coefficient, but do not lower temperatures directly. Fans used to cool electrical equipment or in engines or other machines do cool the equipment directly by forcing hot air into the cooler environment outside the machine. There are three main types of fans used for moving air, axial, centrifugal (also called radial) and cross flow (also called tangenital). The American Society of Mechanical Engineers Performance Testing Code 1. PTC). This type of fan is used in a wide variety of applications, ranging from small cooling fans for electronics to the giant fans used in wind tunnels. Axial flow fans are applied in air conditioning and industrial process applications. Standard axial flow fans have diameters from 3. Special types of fans are used as low pressure compressor stages in aircraft engines. Examples of axial fans are: Table fan: Basic elements of a typical table fan include the fan blade, base, armature and lead wires, motor, blade guard, motor housing, oscillator gearbox, and oscillator shaft. The armature shaft comes out on both ends of the motor, one end of the shaft is attached to the blade and the other is attached to the oscillator gearbox. The motor case joins to the gearbox to contain the rotor and stator. The oscillator shaft combines to the weighted base and the gearbox. A motor housing covers the oscillator mechanism. The blade guard joins to the motor case for safety. Ceiling fan: A fan suspended from the ceiling of a room is a ceiling fan. Most ceiling fans rotate at relatively low speeds and do not have blade guards. Ceiling fans can be found in both residential and industrial/commercial settings. In automobiles, a mechanical fan provides engine cooling and prevents the engine from overheating by blowing or drawing air through a coolant- filled radiator. The fan may be driven with a belt and pulley off the engine's crankshaft or an electric motor switched on or off by a thermostaticswitch. Computer cooling fan for cooling electrical componentsvariable- pitch fan: A variable- pitch fan is used where precise control of static pressure within supply ducts is required. The blades are arranged to rotate upon a control- pitch hub. The fan wheel will spin at a constant speed. As the hub moves toward the rotor, the blades increase their angle of attack and an increase in flow results. Centrifugal fan. Centrifugal fans blow air at right angles to the intake of the fan, and spin the air outwards to the outlet (by deflection and centrifugal force). The impeller rotates, causing air to enter the fan near the shaft and move perpendicularly from the shaft to the opening in the scroll- shaped fan casing. A centrifugal fan produces more pressure for a given air volume, and is used where this is desirable such as in leaf blowers, blowdryers, air mattress inflators, inflatable structures, climate control, and various industrial purposes. They are typically quieter than comparable axial fans. Cross- flow fan. The rotation is clock- wise. The stream guide F is usually not present in modern implementations. The cross- flow or tangential fan, sometimes known as a tubular fan, was patented in 1. Paul Mortier. The fan is usually long in relation to the diameter, so the flow approximately remains two- dimensional away from the ends. The CFF uses an impeller with forward curved blades, placed in a housing consisting of a rear wall and vortex wall. Unlike radial machines, the main flow moves transversely across the impeller, passing the blading twice. The flow within a cross- flow fan may be broken up into three distinct regions: a vortex region near the fan discharge, called an eccentric vortex, the through- flow region, and a paddling region directly opposite. Both the vortex and paddling regions are dissipative, and as a result, only a portion of the impeller imparts usable work on the flow. The cross- flow fan, or transverse fan, is thus a two- stage partial admission machine. The popularity of the crossflow fan in the HVAC industry comes from its compactness, shape, quiet operation, and ability to provide high pressure coefficient. Effectively a rectangular fan in terms of inlet and outlet geometry, the diameter readily scales to fit the available space, and the length is adjustable to meet flow rate requirements for the particular application. Common household tower fans are also cross- flow fans. Much of the early work focused on developing the cross- flow fan for both high and low- flow- rate conditions, and resulted in numerous patents. Key contributions were made by Coester, Ilberg and Sadeh, Porter and Markland, and Eck. One phenomenon particular to the cross- flow fan is that, as the blades rotate, the local air incidence angle changes. The result is that in certain positions the blades act as compressors (pressure increase), while at other azimuthal locations the blades act as turbines (pressure decrease). Uncommon types of fan. A hand- operated bellows is essentially a bag with a nozzle and handles, which can be filled with air by one movement, and the air expelled by another. Typically it would comprise two rigid flat surfaces hinged at one end, where a nozzle is fitted, and with handles at the other. The sides of the surfaces are joined by a flexible and air- proof material such as leather; the surfaces and joining material comprise a bag sealed everywhere but at the nozzle. A simple valve (e. Bellows produce a directed pressurized stream of air; the airflow volume is typically low with moderate pressure. They are an older technology, used mainly to produce a strong and directed airflow unlike non- electric bladed mechanical fans, before the introduction of electricity. A single- acting bellows will only produce airflow during the exhaust stroke.
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