Definitions of turbine

A
form
of
steam
engine
analogous
in
construction
and
action
to
the
water
turbine.
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.

A
horizontal
water
wheel.
X