Turbomachine blade having a sweep law with high flutter margin
A turbomachine rotor blade includes plural blade sections stacked along an axis between a blade root and a blade head defining between the blade root and the blade head the height of the blade, each blade section including a chord and a maximum sweep defined by the maximum length of a segment perpendicular to the chord line and connecting a point of the chord line and a point of a camber line formed of all points located equidistant from the extrados and the intrados in the section, and verifying that the ratio between the maximum sweep and the chord at mid-height of the blade and the same blade head ratio is between 25% and 40% of the ratio between a maximum sweep and a blade root chord.
1. A turbomachine rotor blade comprising
a first blade section, a second blade section and a third blade section stacked along an axis Z between a blade root and a blade tip, the blade root and the blade tip defining between them a height of the blade,
the first blade section being located at the blade root and corresponding to 0% of the height of the blade, the second blade section being located at 50% of the height of the blade, and the third blade section being located at the blade tip and corresponding to 100% of the height of the blade,
each of the three blade sections including
a leading edge,
a trailing edge
a pressure side, and
a suction side,
each of the three blade sections presenting
a chord defined by a length of a chord line connecting the leading edge and the trailing edge,
a camber line formed of all points located equal distance from the suction side and the pressure side,
a maximum camber defined by a maximum length of a segment perpendicular to the chord line and connecting a point of the chord line and a point of the camber line, and
a ratio between the maximum camber and the chord,
wherein
the ratio between the maximum camber and the chord at the second blade section is between 25% and 40% of the ratio between the maximum camber and the chord at the first blade section, and
the ratio between the maximum camber and the chord at the third blade section is between 25% and 40% of the ratio between the maximum camber and the chord at the first blade section.
2. The turbomachine rotor blade according to claim 1 , wherein the ratio between the maximum camber and the chord at the second blade section is between 30% and 35% of the ratio between the maximum camber and the chord at the first blade section.
3. The turbomachine rotor blade according to claim 1 , wherein the ratio between the maximum camber and the chord at the third blade section is between 30% and 35% of the ratio between the maximum camber and the chord at the first blade section.
4. The turbomachine rotor blade according to claim 1 , wherein the ratio between the maximum camber and the chord at the first blade section is between 10% and 20%.
5. The turbomachine rotor blade according to claim 1 , wherein the ratio between the maximum camber and the chord at the second blade section is between 4% and 7%.
6. The turbomachine rotor blade according to claim 1 , wherein the ratio between the maximum camber and the chord at the third blade section is between 4% and 7%.
7. The turbomachine rotor blade according to claim 1 , wherein:
the ratio between the maximum camber and the chord depends on a height of one of the three blade sections and is between:
a minimum piecewise affine function defined by:
a first line segment defined by a minimum ratio between the maximum camber and the chord at the first blade section equal to 14% and a minimum ratio between the maximum camber and the chord at the second blade section equal to 4.7%, and
a second line segment defined by the minimum ratio between the maximum camber and the chord at the of second blade section and a minimum ratio between the maximum camber and the chord at the third blade section equal to 4.7%; and
a maximum piecewise affine function defined by:
a third line segment defined by a maximum ratio between the maximum camber and the chord at the first blade section equal to 17% and a maximum ratio between the maximum camber and the chord at the second blade section equal to 5.7%, and
a fourth line segment defined by the maximum ratio between the maximum camber and the chord at the second blade section and a maximum ratio between the maximum camber and the chord at the third blade section equal to 5.7%.
8. The turbomachine rotor blade according to claim 1 , wherein:
the ratio between the maximum camber and the chord depends on a height of one of the three blade sections and is configured according to a piecewise affine function defined by a first line segment defined for a height between the first blade section and the second blade section and a second line segment defined for a height between the second blade section and the third blade section.
9. A turbomachine fan including a plurality of rotor blades according to claim 1 .
10. A turbomachine including the fan according to claim 9 .