Shroud for an air turbine starter
A shroud is provided for separating an air turbine starter housing from a turbine wheel. The shroud comprises a ring and a bumper. The ring is configured to be disposed between the turbine wheel and the housing and has an outer peripheral surface and an inner peripheral surface that defines a flow channel. The bumper is coupled to and extends radially inwardly from the ring inner peripheral surface and defines a bumper section of the ring flow channel. At least a portion of the bumper section has a cross-sectional flow area that is less than another cross sectional flow area of the ring flow channel.
1. A shroud for separating a turbine wheel from a housing, the shroud comprising:
a ring configured to be disposed between the turbine wheel and the housing, the ring having an anti-rotation notch, an outer peripheral surface, and an inner peripheral surface, the anti-rotation notch formed in the ring, and the inner peripheral surface defining a flow channel; and
a bumper extending radially inwardly from the ring inner peripheral surface and defining a bumper section of the ring flow channel, at least a portion of the bumper section having a cross-sectional flow area that is less than another cross sectional flow area of the ring flow channel.
2. The shroud of claim 1 , wherein the ring comprises a material selected from the group consisting of at least a nickel-based superalloy, a stainless steel alloy, and an iron-based superalloy.
3. The shroud of claim 2 , wherein the nickel-based superalloy comprises a precipitation-hardenable nickel-chromium alloy.
4. The shroud of claim 1 , wherein the ring has an end and the anti-rotation notch is formed in the end.
5. The shroud of claim 1 , further comprising at least one groove formed in the ring outer peripheral surface.
6. The shroud of claim 5 , wherein the at least one groove is formed axially along the ring outer peripheral surface.
7. The shroud of claim 5 , wherein the at least one groove is formed radially along the ring outer peripheral surface.
8. The shroud of claim 5 , wherein the at least one groove is formed from perforations that extend between the ring outer peripheral surface and the ring inner peripheral surface.
9. The shroud of claim 1 , wherein the bumper is integrally formed as part of the ring.
10. A shroud for use in an air turbine starter having a titanium turbine wheel disposed within an aluminum housing, the shroud comprising:
a ring configured to be disposed between the turbine wheel and the housing, the ring comprising a material selected from the group consisting of at least a nickel-based superalloy, a stainless steel alloy, and an iron-based superalloy and having an anti-rotation notch, an outer peripheral surface and an inner peripheral surface, the anti-rotation notch formed in the ring inlet end, and the inner peripheral surface defining a flow channel; and
a bumper extending radially inwardly from the ring inner peripheral surface and defining a bumper section of the ring flow channel, at least a portion of the bumper section having a cross-sectional flow area that is less than another cross sectional flow area of the ring flow channel.
11. The shroud of claim 10 , further comprising at least one groove formed in the ring outer peripheral surface.
12. The shroud of claim 11 , wherein the at least one groove is formed from perforations that extend between the ring outer peripheral surface and the ring inner peripheral surface.
13. The shroud of claim 10 , wherein the ring comprises a precipitation-hardenable nickel-chromium alloy.
14. An air turbine staffer comprising:
a staffer housing;
a shaft rotationally mounted within the staffer housing;
a turbine wheel mounted to the shaft; and
a shroud coupled to the staffer housing and disposed around the turbine wheel, the shroud comprising:
a ring configured to be disposed between the turbine wheel and the housing, the ring having an anti-rotation notch, an outer peripheral surface, and an inner peripheral surface, the anti-rotation notch formed in the ring, and the inner peripheral surface defining a flow channel; and
a bumper extending radially inwardly from the ring inner peripheral surface and defining a bumper section of the ring flow channel, at least a portion of the bumper section having a cross-sectional flow area that is less than another cross sectional flow area of the ring flow channel.
15. The air turbine staffer of claim 14 , wherein the shroud is interference-fit into the staffer housing.
16. The air turbine staffer of claim 15 , wherein:
the ring has an end;
the anti-rotation notch is formed on the ring end; and
the air turbine staffer further comprises a pin coupled between the housing and the anti-rotation notch.
17. The air turbine staffer of claim 14 , wherein the ring comprises a material selected from the group consisting of at least a nickel-based superalloy, a stainless steel alloy, and an iron-based superalloy.
18. The air turbine staffer of claim 17 , wherein the nickel-based superalloy comprises a precipitation-hardenable nickel-chromium alloy.