Swirler

1. A swirler comprising:

a casing;

a pilot body disposed in the casing; and

a plurality of vanes arranged along a circumference of the pilot body,

wherein at least a part of each vane of the plurality of vanes protrudes further to a downstream side end than an end portion of the pilot body,

wherein the casing comprises an inlet portion and an outlet portion, and an expansion portion having an increasing inner diameter between the inlet portion and the outlet portion,

wherein the expansion portion includes a first inclined portion extending from the inlet portion while being slanted, a flat portion cylindrically formed from the first inclined portion without an inclination, and a second inclined portion extending from the flat portion to a location corresponding to ends of the plurality of vanes and being inclined while the inner diameter thereof reduces, and

wherein a plurality of atomizers are disposed at the flat portion for atomizing a fuel of a liquid phase into flow paths between the plurality of vanes.

2. The swirler of claim 1 , wherein the each vane comprises an inclined portion that is inclined with respect to a lengthwise direction of the pilot body, and the inclined portion is disposed inside the expansion portion.

3. The swirler of claim 1 , wherein, when an angle between a corner of the each vane adjacent to the casing and a radial direction of a center axis of the swirler is α, an inclination of the each vane with respect to the center axis direction of the swirler is β, and when an angle between the center axis direction of the swirler and a corner of the each vane adjacent to the outlet portion of the swirler is 0, the angles α, β, and θ satisfy following conditions,

0°<α<90°, 30°<β<60°, 30°<θ<60°.

4. The swirler of claim 1 , further comprising a plurality of gas inlets disposed on the inlet portion of the casing for spraying a fuel of a gas phase into the flow paths between the plurality of vanes.