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An aeolipile (or aeolipyle, or eolipile), also known as a Hero engine, is a simple bladeless radial steam turbine which spins when the central water container is heated. Torque is produced by steam jets exiting the turbine, much like a tip jet〔(jet engine )〕 or rocket engine.〔(NASA Glenn Learning Technologies Project (LTP) )〕 In the 1st century AD, Hero of Alexandria described the device,〔 and many sources give him the credit for its invention. The aeolipile Hero described is considered to be the first recorded steam engine or reaction steam turbine.〔"turbine." Encyclopædia Britannica. 2007. Encyclopædia Britannica Online. 18 July 2007 Pre-dating Hero's writings, a device called an aeolipile was described in the 1st century BC by Vitruvius in his treatise ''De architectura''; however, it is unclear whether it is the same device or a predecessor, as there is no mention of any rotating parts.〔 ==Description and physics== The aeolipile consists of a vessel, usually a "simple" solid of revolution, such as a sphere or a cylinder, arranged to rotate on its axis, having oppositely bent or curved nozzles projecting from it (tipjets). When the vessel is pressurised with steam, steam is expelled through the nozzles, which generates thrust due to the rocket principle〔(Aeolipile )〕 as a consequence of the 2nd and 3rd of Newton's laws of motion. When the nozzles, pointing in different directions, produce forces along different lines of action perpendicular to the axis of the bearings, the thrusts combine to result in a rotational moment (mechanical couple), or torque, causing the vessel to spin about its axis. Aerodynamic drag and frictional forces in the bearings build up quickly with increasing rotational speed (rpm) and consume the accelerating torque, eventually cancelling it and achieving a steady state speed. Typically, and as Hero described the device, the water is heated in a simple boiler which forms part of a stand for the rotating vessel. Where this is the case, the boiler is connected to the rotating chamber by a pair of pipes that also serve as the pivots for the chamber. Alternatively the rotating chamber may itself serve as the boiler, and this arrangement greatly simplifies the pivot/bearing arrangements, as they then do not need to pass steam. This can be seen in the illustration of a classroom model to the right. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「aeolipile」の詳細全文を読む スポンサード リンク
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