Turbofan engine

1. A turbofan engine comprising:

a fan first-stage rotating blade which takes air thereinto and has a hub-side leading edge part extending further in a forward direction of the engine than a tip-side leading edge part and a mid-span leading edge part,

wherein a radius at a root of the hub-side leading edge part is set in a boss ratio of 0 to 0.4, and

wherein the hub-side leading edge part is formed into a convex shape in a span of 0 to 50% and is formed into a linear or a substantially concave shape for the remainder of the span in an outer-radial direction.

2. The turbofan engine according to claim 1 , wherein the hub side leading edge part of the fan first-stage rotating blade is integrally connected as one with the tip side leading edge part and the mid span leading edge part while having a chord length longer than the combined chord lengths of the tip side leading edge part and the mid span leading edge part.

3. The turbofan engine according to claim 1 , wherein the hub side leading edge part, the tip side leading edge part and the mid span leading edge part are formed toward a downstream side of the engine from the hub side to an outer-diameter side, the hub side leading edge part, the tip side leading edge part and the mid span leading edge part merging smoothly with one another to have a smooth continuously curved fan blade shape, and wherein the hub side leading edge part has a chord length such that the hub side leading edge part merges with the mid span leading edge part at a radial position in a span of 5 to 50% of a trailing edge part.

4. The turbofan engine according to claim 1 , wherein the fan first-stage rotating blade is formed into a shape in which two or a plurality of blades are rigidly connected as one with each other by a chemical process.