US 2019/0193851 A1Published application

Thick airfoil shapes for blade necks and for blade cuff fairings for an aircraft rotor

AssigneeAirbus Helicopters

InventorsDavid ALFANO, Damien DESVIGNE

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Abstract

A thick airfoil shape that is to form a blade neck for blades, the blade neck connecting a blade root to a streamlined portion of the blade, and/or a blade cuff connecting a blade to the hub of an aircraft rotor. The thick airfoil shape has a leading edge and a trailing edge together with thick airfoil profiles for which the particular positions of points defining the maximum thickness of each airfoil profile make it possible to improve the aerodynamic behavior of the thick airfoil shapes and of the rotor during rotation of the rotor while the aircraft is advancing, for the blade both when it is advancing and when it is retreating. The thick airfoil shape also serves to reduce the vibration as generated by a wake from the rotor on a tail boom or a horizontal and/or vertical stabilizer of the aircraft.

Claims21

Dependent claims

A thick airfoil shape for arranging between a rotary hub of a rotor of an aircraft and a streamlined portion of a blade of the rotor, the thick airfoil shape extending firstly spanwise in a longitudinal direction from a first end zone towards a second end zone, and secondly in a transverse direction (Y) from a leading edge to a trailing edge, the thick airfoil shape being made up of a succession of thick airfoil profiles situated in planes parallel to a transverse plane (PYZ) perpendicular to the spanwise longitudinal direction (X), each thick airfoil profile having a suction side profile and a pressure side profile, each thick airfoil profile being defined by a chord c between the leading edge and the trailing edge, by a maximum thickness t equal to a maximum distance between the suction side profile and the pressure side profile measured perpendicularly to the chord c, and by a relative thickness t/c equal to the ratio of the maximum thickness t divided by the chord c, the relative thickness t/c being greater than or equal to 20% for each thick airfoil profile, each airfoil profile passing via extreme points (C0, C1, C2, C3), each extreme point (C0, C1, C2, C3) being defined in a reference frame (U, V) attached to the airfoil profile and itself defined by an abscissa axis (U) formed by the direction of the chord c and by an ordinate axis (V) perpendicular to the abscissa axis (U), one unit of the abscissa and ordinate axes (U, V) being equal to the chord c, a first extreme point (C0) of coordinates being situated at the leading edge, a second extreme point (C2) of coordinates being situated at the trailing edge, and third and fourth extreme points (C1, C3) forming the maximum thickness t of the airfoil profile, tangents to each airfoil profile (11) at the third and fourth extreme points (C1, C3) being defined parallel to the abscissa axis (U);

wherein the coordinates (uCi, vCi) of the third and fourth extreme points (C1, C3) in the reference frame (U, V) are defined as a function of the relative thickness t/c and are situated within ranges bounded by low values (B) and high values (H) given in the following table:
t/c
uC1
vC1
uC3
vC3
20%
B
0.55
0.12
0.55
−0.08
H
0.70
0.16
0.75
−0.04
25%
B
0.63
0.14
0.55
−0.11
H
0.73
0.19
0.75
−0.06
30%
B
0.65
0.18
0.62
−0.12
H
0.75
0.22
0.72
−0.08
35%
B
0.65
0.20
0.62
−0.15
H
0.75
0.24
0.73
−0.11
40%
B
0.48
0.23
0.45
−0.17
H
0.63
0.28
0.65
−0.12
50%
B
0.35
0.28
0.37
−0.22
H
0.49
0.37
0.57
−0.13
60%
B
0.25
0.34
0.30
−0.26
H
0.42
0.45
0.50
−0.15
70%
B
0.20
0.44
0.20
−0.26
H
0.40
0.56
0.30
−0.14
80%
B
0.36
0.47
0.19
−0.33
H
0.52
0.57
0.31
−0.23
90%
B
0.37
0.47
0.20
−0.43
H
0.52
0.59
0.30
−0.31
100%
B
0.40
0.45
0.22
−0.55
H
0.50
0.60
0.32
−0.40

124 more elements

A method of obtaining a thick airfoil shape for arranging between a rotary hub of a rotor of an aircraft and a streamlined portion of a blade of the rotor, the thick airfoil shape extending firstly spanwise in a longitudinal direction (X) from a first end zone towards a second end zone, and secondly in a transverse direction (Y) from a leading edge to a trailing edge, the thick airfoil shape being made up of a succession of thick airfoil profiles situated in planes parallel to a transverse plane (PYZ) perpendicular to the spanwise longitudinal direction (X), each thick airfoil profile having a suction side profile and a pressure side profile, each thick airfoil profile being defined by a chord c between the leading edge and the trailing edge, by a maximum thickness t equal to a maximum distance between the suction side profile and the pressure side profile measured perpendicularly to the chord c, and by a relative thickness t/c equal to the ratio of the maximum thickness t divided by the chord c, the relative thickness t/c being greater than or equal to 20% for each thick airfoil profile;

wherein the method comprises the following steps for defining each airfoil profile:
a first creation step for creating (m+1) characteristic points (A0, . . . , Ai, . . . , Am) belonging to the airfoil profile (11), i being a positive integer lying in the range 0 to m, each characteristic point (Ai) being defined in a reference frame (U, V) attached to the airfoil profile and defined by an abscissa axis (U) formed by the direction of the chord c and by an ordinate axis (V) perpendicular to the abscissa axis (U), one unit of the abscissa and ordinate axes (U, V) being equal to the chord c;
a second creation step (102) for creating control points (Bi.j), n control points (Bi.j) being situated respectively between two consecutive characteristic points (Ai, Ai+1) and being construction points for constructing the airfoil profile between the two constructive characteristic points (Ai, Ai+1), n being a positive integer greater than or equal to 2, j being a positive integer lying in the range 1 to n, (i+1) being replaced by the value zero “0” when i is equal to m;
and
a determination step for determining the airfoil profile, (m+1) curves respectively connecting together two consecutive characteristic points (Ai, Ai+1) and being constructed from the control points (Bi.j), the (m+1) curves (41-44) being connected in pairs to form the airfoil profile, the airfoil profile passing through extreme points (C0, C1, C2, C3), a first extreme point (C0) of coordinates being situated at the leading edge, a second extreme point (C2) of coordinates being situated at the trailing edge, and third and fourth extreme points (C1, C3) forming the maximum thickness t of the airfoil profile, the tangents of each airfoil profile at the third and fourth extreme points (C1, C3) being defined parallel to the abscissa axis (U), and the coordinates (uCi, vCi) of the third and fourth extreme points (C1, C3) in the reference frame (U, V) being defined as a function of the relative thickness t/c and being situated within ranges bounded by low values (B) and high values (H) given in the following table:
t/c
uC1
vC1
uC3
vC3
20%
B
0.55
0.12
0.55
−0.08
H
0.70
0.16
0.75
−0.04
25%
B
0.63
0.14
0.55
−0.11
H
0.73
0.19
0.75
−0.06
30%
B
0.65
0.18
0.62
−0.12
H
0.75
0.22
0.72
−0.08
35%
B
0.65
0.20
0.62
−0.15
H
0.75
0.24
0.73
−0.11
40%
B
0.48
0.23
0.45
−0.17
H
0.63
0.28
0.65
−0.12
50%
B
0.35
0.28
0.37
−0.22
H
0.49
0.37
0.57
−0.13
60%
B
0.25
0.34
0.30
−0.26
H
0.42
0.45
0.50
−0.15
70%
B
0.20
0.44
0.20
−0.26
H
0.40
0.56
0.30
−0.14
80%
B
0.36
0.47
0.19
−0.33
H
0.52
0.57
0.31
−0.23
90%
B
0.37
0.47
0.20
−0.43
H
0.52
0.59
0.30
−0.31
100%
B
0.40
0.45
0.22
−0.55
H
0.50
0.60
0.32
−0.40

128 more elements

Dependencies are inferred from the claim text.