Stator vane of fan or compressor
To provide a stator vane of a fan or compressor that is reduced in loss by enlarging a laminar flow area over a blade surface. With the stator vane, provided that an angle formed by a tangent to the blade surface at a point and the axial direction of the turbofan engine, that is, a parameter that is a blade surface angle normalized is referred to as a normalized blade surface angle, an upper limit is set for the change rate in the chord direction of the normalized blade surface angle on the pressure surface, and an upper limit is set for the normalized blade surface angle at a predetermined location in the chord direction on the suction surface.
1. A stator vane of a fan or compressor that is a component of a turbofan engine, comprising:
a blade part, an outer band, and an inner band,
wherein an airfoil, which is a cross section, of the stator vane at each location in a height direction is formed by a concave pressure surface and a convex suction surface each of which extends between a leading edge and a trailing edge of the stator vane, and
in the cross section,
wherein an angle formed by a tangent at a point on the suction surface and an axial direction of the turbofan engine is referred to as a suction surface's blade surface angle (βSS), the suction surface's blade surface angle at the leading edge is referred to as a suction surface's inlet blade surface angle (βSSin), the suction surface's blade surface angle at the trailing edge is referred to as a suction surface's exit blade surface angle (βSSex), and a parameter (δSS) defined by a formula (1) is referred to as a suction surface's normalized blade surface angle:
δ SS =(β SS in−β SS )/(β SS in−β SSex ) formula (1)
wherein an angle formed by a tangent at a point on the pressure surface and the axial direction of the turbofan engine is referred to as a pressure surface's blade surface angle (βPS), an angle formed by a tangent at a point on a camber line of the airfoil and the axial direction of the turbofan engine is referred to as a camber line angle, the camber line angle at the leading edge is referred to as an inlet camber line angle (γin), the camber line angle at the trailing edge is referred to as an exit camber line angle (γex), and
a parameter (δPS) defined by formula (2) is referred to as a pressure surface's normalized blade surface angle:
δ PS =(γin−β PS )/(γin−γ ex ) (2)
wherein a line segment connecting the leading edge and the trailing edge is referred to as a chord, a length of the chord is referred to as a chord length (c), and a parameter (xc) defined as a distance (x) from a point on the pressure surface or suction surface to the leading edge measured in a direction parallel with the chord divided by the chord length (c) is referred to as a chord ratio,
the suction surface's normalized blade surface angle at a location where the chord ratio is 0.05 is equal to or less than 0.35,
the suction surface's normalized blade surface angle at a location where the chord ratio is 0.34 is equal to or less than 0.62, and
a change rate (d(δPS)/dxc) in a chord direction of the pressure surface's normalized blade surface angle in a range of the chord ratio from 0 to 0.95 is equal to or less than 0.9.