Turbine
A turbine (/ˈtɜːrbaɪn/ or /ˈtɜːrbɪn/) (from the Greek τύρβη, tyrbē, or Latin turbo, meaning vortex)[1][2] is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work.
[3] A turbine is a turbomachine with at least one moving part called a rotor assembly, which is a shaft or drum with blades attached.
Hero of Alexandria demonstrated the turbine principle in an aeolipile in the first century AD and Vitruvius mentioned them around 70 BC.
The word "turbine" was first applied to this kind of device in 1822 by the French mining engineer Claude Burdin in a memo, "Des turbines hydrauliques ou machines rotatoires à grande vitesse", which he submitted to the Académie royale des sciences in Paris.
[4] The word derives from the Latin turbo, meaning "vortex" or "top", and was in use in French to describe certain seashells.
The resulting impulse spins the turbine and leaves the fluid flow with diminished kinetic energy.
The casing contains and directs the working fluid and, for water turbines, maintains the suction imparted by the draft tube.
For compressible working fluids, multiple turbine stages are usually used to harness the expanding gas efficiently.
Reaction turbines are better suited to higher flow velocities or applications where the fluid head (upstream pressure) is low.
Wind turbines use an airfoil to generate a reaction lift from the moving fluid and impart it to the rotor.
Formulae for the basic dimensions of turbine parts are well documented and a highly efficient machine can be reliably designed for any fluid flow condition.
Velocity triangles can be constructed at any section through the blading (for example: hub, tip, midsection and so on) but are usually shown at the mean stage radius.
Mean performance for the stage can be calculated from the velocity triangles, at this radius, using the Euler equation: Hence: where: The turbine pressure ratio is a function of
This number describes the speed of the turbine at its maximum efficiency with respect to the power and flow rate.
The liquid hydrogen turbopump is slightly larger than an automobile engine (weighing approximately 700 lb) with the turbine producing nearly 70,000 hp (52.2 MW).
