A | cross sectional area |

C | absolute velocity |

h | head loss |

H | head |

n | number of circulations (number of times the fluid passes through the impeller blades) |

N | rotational speed (rpm) |

p | pressure |

K | is the loss coefficient related to the friction forces on the side channel wall |

K | is the loss coefficient that takes into account all the losses due to enlargements or restrictions of the flow and to turbulence share forces in the vanes related to the circulatory flow rate. |

Q | blower flow rate |

r | radius |

u | peripheral velocity |

z | number of impeller blades |

| increase in pressure in the side channel |

| dimensionless flow coefficient |

| dimensionless head coefficient |

| density |

| efficiency |

| angular speed |

| blade angle (the theoretical angle of the flow) |

| flow angle (the actual angle of the flow) |

| slip factor |

| effective angle from the inlet to the outlet of the blower |