Compressor and a turbine engine with optimized efficiency
A turbine engine compressor including a casing having its inside wall defining an aerodynamic reference surface for a gas-passing passage and in which a rotor wheel having radial blades is mounted. A circumferential trench is formed in the inside wall of the casing. Its shape is defined from upstream to downstream by three surfaces, respectively an upstream surface, a middle surface, and a downstream surface, which surfaces are substantially conical. The upstream surface extends upstream from the leading edges of the blades. The middle surface is substantially parallel to the aerodynamic reference surface. The downstream surface extends downstream at least as far as the trailing edges of the blades. The junction between the middle and downstream surfaces is in a range of 30% to 80% or 50% to 65% of the axial length of the blades starting from their leading edges.
1. An axial flow turbine engine compressor comprising:
a casing presenting an inside wall of general shape that defines an aerodynamic reference surface defining a gas-passing passage;
a rotor wheel mounted to rotate relative to the casing in the passage;
the rotor wheel carrying a plurality of radial blades, each having a tip, a leading edge, and a trailing edge;
a circumferential trench being formed in the inside wall of the casing;
a shape of the trench being defined by three substantially conical surfaces, of an upstream surface, a middle surface, and a downstream surface, the surfaces following one after another from upstream to downstream;
the middle surface being substantially parallel to the aerodynamic reference surface;
the downstream surface extending downstream at least as far as the trailing edges of the blades;
the upstream surface being located entirely upstream from the leading edges of the blades; and
a junction between the middle and downstream surfaces is situated in a range of 30% to 80% of an axial length of the blades starting from the leading edge.
2. A compressor according to claim 1 , wherein the upstream surface is entirely located upstream from the leading edges of the blades in a range of 5% to 25% of an inter-blade pitch between the tips of two consecutive blades in the circumferential direction.
3. A compressor according to claim 1 , wherein the downstream surface extends downstream from the trailing edges of the blades in a range of 5% to 25% of an inter-blade pitch between tips of two consecutive blades in the circumferential direction.
4. A compressor according to claim 1 , wherein, in longitudinal section, the downstream surface forms an angle of less than 15° with the aerodynamic reference surface.
5. A compressor according to claim 1 , wherein, in longitudinal section, the upstream surface forms an angle of less than 90° with the aerodynamic reference surface.
6. A compressor according to claim 1 , wherein the blades extend inside or as far as the aerodynamic reference surface without penetrating into an inside of the trench.
7. A compressor according to claim 1 , wherein a substantially constant radial clearance extends between the tips of the blades and the trench.
8. A turbo engine including at least one compressor according to claim 1 .
9. A turbo engine including at least one compressor according to claim 2 .
10. A turbo engine including at least one compressor according to claim 3 .
11. A turbo engine including at least one compressor according to claim 4 .
12. A turbo engine including at least one compressor according to claim 5 .
13. A compressor according to claim 2 , wherein the upstream surface is entirely located upstream from the leading edges of the blades in a range of 7% to 20% of an inter-blade pitch between the tips of two consecutive blades in the circumferential direction.
14. A compressor according to claim 3 , wherein the downstream surface extends downstream from the trailing edges of the blades in a range of 7% to 20% of an inter-blade pitch between tips of two consecutive blades in the circumferential direction.
15. A compressor according to claim 4 , wherein, in longitudinal section, the downstream surface forms an angle of less than 5° with the aerodynamic reference surface.
16. A compressor according to claim 5 , wherein, in longitudinal section, the upstream surface forms an angle of less than 30° with the aerodynamic reference surface.