NNR IN RAPIDLY ROTATED METALS By - Nottingham eTheses ...

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The problem may also be overcome by using a propelling gas in
which the velocity of sound is much higher. The maximum velocity
of the rotor is then determined by other factors - usually
mechanical - before the sonic limit is reached.
4.3 THE CONICAL ROTOR SYSTEM
4.3.1 DESCRIPTION
This rotor system is based on the type originally described
(54)
by Henriot and Huguenard and by Beams ý55,56),
The conical-
shaped rotor base sits in a stator in which there are a series of
jets. The gas passing through these jets serves both to lift
the rotor off the base stator and to drive it round. Because of
the Bernoulli forces the rotor does not fly out of the stator,
but is supported by a cushion of air.
The present system, shown in Figure 4.1, is a compromise bet-
ween sample size and the higher rotation speeds possible with
smaller diameter rotors. The rotors have a series of 20 flutes
cut to a depth of 0.030" at an angle of approximately 300 to
the vertical axis. In the past much effort has gone into optimiz-
ing the number, position and size of the jets in the stator(57,58).
The most efficient combination of rotor and stator has been found
to vary with each individual rotor. Generally the best results
were achieved here using stators with 23 0.015" diameter jets set
in a single ring. Each jet was drilled at an angle of 600 to a
vertical line through the-apex of the stator and in a plane tangent-
ial to the rotor flutes at each point.
I