1. A fan for a rotating electrical machine, the fan comprising:
a plurality of fan blades; and
5 a flow separator for separating a first airflow entering the fan from a
radially outwards part of the machine and second airflow entering the fan from a
radially inwards part of the machine,
wherein the flow separator extends partway through the fan blades in a
direction of airflow.
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2. A fan according to claim 1, wherein the first airflow is from around a stator
and the second airflow is from around a rotor.
3. A fan according to claim 1 or 2, wherein the flow separator defines a first
15 annular entry path on its radially outwards side and a second annular entry path
on its radially inwards side.
4. A fan according to any of the preceding claims, the flow separator
comprising a leading end which extends axially forwards from the fan blades.
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5. A fan according to claim 4, wherein the leading end of the flow separator
is substantially cylindrical.
6. A fan according to any of the preceding claims, wherein the fan is
25 arranged such that the first airflow and the second airflow converge in the fan
blades.
7. A fan according to claim 6, wherein the fan is arranged such that the first
airflow and the second airflow are in substantially the same direction at their
30 confluence.
8. A fan according to any of the preceding claims, the flow separator
comprising a trailing end which meets or extends partway into the fan blades.
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9. A fan according to any of the preceding claims, wherein the trailing end is
arranged to turn airflow from a substantially axial direction to a substantially radial
direction.
5 10. A fan according to any of the preceding claims, further comprising a
backplate for turning airflow from a substantially axial direction to a substantially
radial direction.