Fan for rotary electrical machine

A fan (100) for a rotary electrical machine, the fan having an axis of rotation and comprising a support plate coaxial with the axis of rotation and blades (101) non-moveably secured to an axial face of the support plate, a number of the blades (101) being a prime number,

• at least one characteristic of the blades is progressively variable in the direction of a circumference of the fan around the axis of rotation for a majority of the blades, the progressively variable blades being consecutive blades, the at least one characteristic selected from the group consisting of:
• a spacing angle (102) between a straight line passing radially via a characteristic point (103) of one of the blades and the axis of rotation of the fan (104) and a straight line passing via the characteristic point (105) of other of the blades adjacent to the one of the blades and the axis of rotation of the fan, wherein the characteristic point of each of the blades is a radially outer end point of each of the blades (101) furthest from the axis of rotation and disposed on the axial face of the support plate within an outer periphery of the support plate;
• a height of each of the majority of the blades;
• a length of each of the majority of the blades;
• and
• an angle of inclination (605) between a straight line (602) passing via two characteristic points of one of the blades, and a straight line (604) passing via two characteristic points of other of the blades adjacent to the one of the blades, wherein the two characteristic points of each of the blades are a radially outer end point of each of the blades furthest from the axis of rotation and a radially inner end point of each of the blades closest to the axis of rotation, both the radially outer and inner end points disposed on the axial face of the support plate within an outer periphery of the support plate.