Engine compressor, particularly aircraft jet engine compressor, fitted with an air bleed system
View Patent ↗A compressor including at least one cascade of fixed vanes, the vanes of which are mounted on a wall and between them form air-flow passages, and an air bleed system which bleeds air from the passages between two vanes, through openings made in the wall, the openings being discontinuous and each including a plurality of orifices arranged one behind the other in a direction of the air flow. An upstream orifice of each opening has a larger cross-sectional area than downstream orifices of the opening, and a number and cross section of the downstream orifices are adjusted to suit a predetermined bleed-off flow rate.
1. A compressor comprising:
at least one fixed cascade of vanes, the vanes of which are mounted on a wall and between them form airflow passages; and
an air bleed system, which bleeds air from the passages between two vanes through openings made in the wall, the openings being discontinuous and each opening including a plurality of orifices arranged one behind the other in a direction of the airflow,
wherein an upstream orifice of each respective opening has a cross-sectional area which is larger than areas of cross sections of downstream orifices of the respective opening, and a number and cross sections of the downstream orifices are adjusted to suit a predetermined bleed-off suction flow,
wherein the number and cross sections of the orifices of an opening depend on a predetermined suction flow generated by the air bleed system, and
wherein a number N of orifices of an opening satisfies the following relation:
Δβ·( S/C )/( N·D )≦300
in which:
Δβ represents deviation of the fluid on passage through the cascade of vanes;
S/C represents relative pitch of the cascade of vanes, where S is the distance between two successive vanes and C is the chord of a vane; and
D represents the predetermined suction flow.
2. The compressor as claimed in claim 1 , wherein the upstream orifice of each opening is centered in relation to a position situated laterally near a suction side of a vane and axially at between 10% and 30% of axial length of the vane from its upstream extremity.
3. The compressor as claimed in claim 1 , wherein the upstream orifice of at least some of the openings exhibits, through the wall, a shape slanting in a downstream direction.
4. The compressor as claimed in claim 1 , wherein the upstream orifice of at least some of the openings exhibits, through the wall, a streamlined shape.
5. An engine, or an aircraft jet engine, comprising at least one compressor and with an air bleed system, incorporating a compressor as claimed in claim 1 .