In Fig. 70 the nozzle points downwards, and the left side of
the wheel has to be trued. Therefore B1 has its convex, B2 its concave,
side facing the reader, as it were.
The Nozzle is a 1-1/2 inch piece of brass bar. Drill a 1/20-inch hole
through the centre. On the outside end, enlarge this hole to 1/8 inch to a
depth of 1/8 inch. The nozzle end is bevelled off to an angle of 20
degrees, and a broach is inserted to give the steam port a conical section,
as shown in Fig. 72, so that the steam may expand and gain velocity as it
approaches the blades. Care must be taken not to allow the broach to enter
far enough to enlarge the throat of the nozzle to more than 1/20 inch.
[Illustration: FIG. 72.--Nozzle of turbine, showing its position
relatively to buckets.]
Fixing the Nozzle.--The centre of the nozzle discharge opening is
1-13/16-inches from the centre of the wheel. The nozzle must make an angle
of 20 degrees with the side of the casing, through which it projects far
enough to all but touch the nearer edges of the vanes. (Fig. 72.) The wheel
can then be adjusted, by means of the spindle nuts, to the nozzle more
conveniently than the nozzle to the wheel.
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