Counter-rotating axial flow fan

摘要

A counter-rotating axial flow fan (1') with improved characteristics and reduced noise compared to the related art can be provided. Defining the number of front blades (28') as N, the number of stationary blades (61') as M, and the number of rear blades (51') as P, and defining the maximum axial chord length of the front blades (28') as Lf, the maximum axial chord length of the rear blades (51') as Lr, the outside diameter of the front blades (28') as Rf, and the outside diameter of the rear blades (51') as Rr, the counter-rotating axial flow fan satisfies the following two relationships: N ‰¥ P > M; and Lf/(RfxÀ/N) ‰¥ 1.25 and/or Lr/(RrxÀ/P) ‰¥ 0.83.