The Portland daily press., 1897-07-20
THE MARVELLOUS TURBINA.
Description of the Worlds Fastest and
Most Novel Steam Vessel.
(The London Times.)

In all the magnificent collection of war
vessels now assem- bled at Spithead there
is none more interesting than little
craft that has r ecently come round from
the Tyne. This is the Turbine, a torpedo
boat, 100 feet long over all, 9 feet beam.
and A tons displacement. AS she floats
she is the fastest vessel in the world.
having made, on trial off the Tyne, a
mean of 80 "a knots. This remarkable
performance is due to the fact that, in
place of being fitted with the ordinary
marine type of reciprocating engine, she
has her motive power supplied by three
steam turbines Of the type invented by
the Hon. Charles Parsons. Before de-
scribing the Turbina more fully it will
be we'll to give brief description of the
principle upon which the Parsons turbine
works. 1t consists essentially of a cylin-
drical case Attached to the inner surface
of the case are number of rows of in
wardly projecting blades, which extend
radially toward the axis of the engine.
The function of these is to guide the
steam for purpose to be hereafter re-
there passes shaft which serves to con-
vey the power generated, and, in the case
of a vessel, is directly coupled to the
screw-shaft. On the axial shaft is mount
ed a light drum, the external diameter of
which is some inches less than the inter
nal diameter of the case. When, there
fore, the drum is placed inside the cas- e
and co-axial with it, there is left an an
.nular space. This space is occupied by
the blades, projecting inward from the
case before referred to, and by other rows
of outwardly projecting blades attached
to the outer surface of the light drum.
The blades on the outer cylinder are
called "guide blades,' and the similar
blades are known as knowing blades"
When steam at pressure is admitted to
the annular space it first comes in contact
with ring of the fixed guide blades,
which are so formed as to direct the flow
of steam onto the adjacent ring of moving
blades at an angle to the surface of the
blades to rotate round the axis of the en-
gine. AS they are firmly attached to the
DRUM, and as the latter is fixed to the
shaft, motive power for screw propeller
or dynamo is thus obtained. There are,
OF course, numerous alternate rings of
g'lidesblades and moving blades. there
being perhaps, eighty rows of both in an
ordinary Parsons turbine. 1t will be
seen that the fundamental principle is
that of a water turbine, or, to take
more elementary example, of windmill
In all three fluid, steam in this case,
strikes an inclined or curved surface and
thus produces rotary motion. The object
of the fixed guide blades will be apparent
When the steam has been directed on one
course by ring of moving blades it re-
quires to have it's line of motion altered
so that it will strike the next ring of
moving blades at the re-
quired angle. The guide blades are SO
shaped as to effect this purpose. In order
to use steam economically it must be
worked expansively, and it is this problem
which Mr.. Parsons has succeeded in
solving by the following ingenious device. |
AS the steam does work 1t necessarily in
creases in volume, and loses proportions
ately in pressure. In order to accommo-
date the increased volume, additional
blade area is given by gradually increas-
ing the annular space and the size of the
blades. In this way we have the analogue
of the two diameter cylinders of the Or
binary compound engine, but in the tur-
bine the action is more perfect, because it
is gradual and continuous, and, there
fore, is capable of being carried much
further AS an instance of this.it may. be
stated that in the Turbinas engine the
steam is expanded 40 fold as against
16-fold in ordinary triple expansion
marine engines.
The Turbina has three turbines, which
drive directly three propeller shafts. In
order to work these motors most efficient
" high speed of revolutions is required.
The revolutions at full speed are 400, a
rate of turning which, it is needless to
say, has never before been attempted in
any vessel. This high speed precludes
the use of a propeller Of ordinary dimen-
sions, and to obtain. the necessary grip
of the water three screws are placed on
each shaft, or nine III all. The propeller
question in connection with this boat is
one Of remarkable interest, and Mr.. Par
sonss experiments have already led to a
good deal of light being thrown on very
obscure detail of marine engineering,
more especially in regard to cavitation.
1t would, however, not be possible to en-
ter into the subject here. 1t will be suffi-
cient to say that the propeller difficulty
has been SO effectively overcome, or per-
haps one should say masked, as to allow
the remarkable speed before mentioned to
be obtained. This, of course, is chiefly