turbine

turbine
    n 1: rotary engine in which the kinetic energy of a moving fluid
         is converted into mechanical energy by causing a bladed
         rotor to rotate
    

Turbine \Tur"bine\ (t[^u]r"b[i^]n), n. [L. turbo, -inis, that
   which spins or whirls round, whirl.]
   1. A water wheel, commonly horizontal, variously constructed,
      but usually having a series of curved floats or buckets,
      against which the water acts by its impulse or reaction in
      flowing either outward from a central chamber, inward from
      an external casing, or from above downward, etc.; -- also
      called {turbine wheel}.
      [1913 Webster]

   Note: In some turbines, the water is supplied to the wheel
         from below, instead of above. Turbines in which the
         water flows in a direction parallel to the axis are
         called parallel-flow turbines.
         [1913 Webster]

   2. A type of rotary engine with a set of rotating vanes,
      diagonally inclined and often curved, attached to a
      central spindle, and obtaining its motive force from the
      passage of a fluid, as water, steam, combusted gases, or
      air, over the vanes. Water turbines are frequently used
      for generating power at hydroelectric power stations, and
      steam turbines are used for generating power from coal- or
      oil-fired electric power stations. Turbines are also found
      in jet engines, and in some automobile engines.

   Note: In the 1913 dictionary, the turbine was further
         decribed thus: "There are practically only two distinct
         kinds, and they are typified in the de Laval and the
         Parsons and Curtis turbines. The

   {de Laval turbine} is an impulse turbine, in which steam
      impinges upon revolving blades from a flared nozzle. The
      flare of the nozzle causes expansion of the steam, and
      hence changes its pressure energy into kinetic energy. An
      enormous velocity (30,000 revolutions per minute in the 5
      H. P. size) is requisite for high efficiency, and the
      machine has therefore to be geared down to be of practical
      use. Some recent development of this type include turbines
      formed of several de Laval elements compounded as in the
      ordinary expansion engine. The Parsons turbine is an
      impulse-and-reaction turbine, usually of the axial type.
      The steam is constrained to pass successively through
      alternate rows of fixed and moving blades, being expanded
      down to a condenser pressure of about 1 lb. per square
      inch absolute. The Curtis turbine is somewhat simpler than
      the Parsons, and consists of elements each of which has at
      least two rows of moving blades and one row of stationary.
      The bucket velocity is lowered by fractional velocity
      reduction. Both the Parsons and Curtis turbines are
      suitable for driving dynamos and steamships directly. In
      efficiency, lightness, and bulk for a given power, they
      compare favorably with reciprocating engines."
      [Webster 1913 Suppl. +PJC]