Fan impeller structure

A fan impeller structure comprising:

• a hub having a top and a sidewall and
• a plurality of blades circumferentially spaced on the sidewall;
• each of the blades having a root portion at a radially inner end of the blade, the root portion connected to the sidewall and a tip portion at an opposite, radially outer end of the blade, the tip portion forming a barrier zone at a radially outermost edge of the blade, the barrier zone including one continuously inclining lifted section having a first width and one continuously declining declined section having a second width, and wherein the lifted section is discontinuous from the declined section, the root portion having a geometry different from the continuously inclining lifted section having the first width and different from the continuously declining declined section having the second width of the barrier zone and the root portion having a curvature describing a non-linear structure, such that the barrier zone prevents fluid at a lower side of the blade from turning over to an upper side of the blade owing to a difference in the pressure distributed over the upper and the lower side of the tip portion of the blade to thereby enable reduced vortices at the tip portions of the blades and reduced aerodynamic noise.