An aeolipile (or aeolipyle, or eolipile), also known as a Hero's engine, is a simple, bladeless radial steam turbine that spins when the central water container is heated. Water within the spherical container is heated to produce steam, which exits through nozzles directed at right angles to the radial direction, and by Newton’s third law, the steam ejected by these jets produces a torque about the rotation axis.
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