Inducer with shrouded rotor for high speed applications
View Patent ↗An inducer rotor rotatably mountable in an inducer for pressurizing fluid traveling through the inducer. The inducer rotor includes a hub. The hub has a central axis and a plurality of blades extending radially outward from the hub. Each blade extends from a root portion that is next to the hub, to a tip portion that is opposite the root. The rotor further includes a shroud extending circumferentially between each pair of adjacent blades within the plurality of blades. The shroud has an inner surface facing the central axis and an outer surface that is opposite the inner surface. Between the inner and outer surface of the shroud is defined a thickness. The shroud thickness varies circumferentially around the shroud.
1. An inducer rotor rotatably mountable in an inducer for pressurizing fluid traveling through the inducer, said inducer rotor comprising:
a hub having a central axis:
a plurality of blades connected to the hub, each of said plurality of blades extending radially outward from a root adjacent the hub to a tip opposite the root; and
a unitary, one-piece, shroud extending circumferentially between at least one pair of adjacent blades within the plurality of blades, said shroud having an inner surface facing the central axis, an outer surface opposite the inner surface and a thickness extending between said inner and outer surface, said thickness varying circumferentially around the shroud, wherein said shroud thickness varies around the shroud so that the outer surface of the shroud is substantially circular when the rotor is rotating at a predetermined rotational operating speed.
2. An inducer rotor as set forth in claim 1 wherein said shroud thickness varies around the shroud so that the outer surface of the shroud varies from circular by no more than 0.30 inches when the rotor is rotating at the predetermined rotational operating speed.
3. An inducer as set forth in claim 1 wherein the blade tips have a circumferential tip speed of about 936 ft/sec when the rotor is operating at the predetermined rotational operating speed.
4. An inducer as set forth in claim 1 wherein the shroud extends circumferentially between blades adjacent the blade tips.
5. An inducer rotor as set forth in claim 4 wherein the shroud thickness varies from a predetermined minimum thickness located circumferentially between each adjacent pair of blade tips to a predetermined maximum thickness located adjacent each blade tip.
6. An inducer rotor as set forth in claim 5 wherein the minimum shroud thickness is located circumferentially midway between each adjacent pair of blade tips.
7. An inducer rotor as set forth in claim 5 wherein a shroud radius varies circumferentially along each shroud between adjacent blades of the plurality of blades such that the shroud radius decreases from a maximum shroud radius adjacent the blades to a minimum shroud radius as a midpoint of the shroud between the blades.
8. An inducer rotor having a predetermined rotational speed mountable in an inducer for pressurizing fluid traveling through the inducer, the inducer comprising a housing surrounding the rotor having an interior surface facing the outer surface of the shroud, said housing extending axially from an inlet through which fluid is received at an inlet pressure to an outlet downstream from said inlet through which fluid is discharged at an outlet pressure higher than said inlet pressure, the inducer rotor comprising:
a hub having a central axis;
a plurality of blades connected to the hub, each of said plurality of blades extending radially outward from a root adjacent the hub to a tip opposite the root; and
a unitary, one-piece, shroud extending circumferentially between at least one pair of adjacent blades within the plurality of blades, said shroud having an inner surface facing the central axis, an outer surface opposite the inner surface and a thickness extending between said inner and outer surface, said thickness varying circumferentially around the shroud, wherein the shroud extends circumferentially between blades adjacent the blade tips.
9. An inducer rotor as set forth in claim 8 having a predetermined operating pressure between said inlet and outlet pressures, and wherein said shroud thickness varies around the shroud so that the outer surface of the shroud is substantially circular when pressure within the rotor shroud generally equals the predetermined operating pressure.
10. An inducer rotor as set forth in claim 9 wherein said shroud thickness varies around the shroud so that the outer surface of the shroud varies from circular by no more than about 0.30 inches when the rotor is rotating at a predetermined rotational operating speed.
11. An inducer for pressurizing a fluid comprising:
a housing having an interior surface facing a central axis, an inlet through which fluid is received into the housing at an inlet pressure, and an outlet downstream from the inlet through which fluid is discharged from the housing at an outlet pressure higher than said inlet pressure;
a rotor rotatably mounted in the housing, said rotor comprising a hub centered on the central axis, a plurality of blades connected to the hub, each of said plurality of blades extending radially outward from a root adjacent the hub to a tip opposite the root and axially rearward from a leading edge to a trailing edge opposite the leading edge, and a shroud extending circumferentially between each pair of adjacent blades within the plurality of blades, said shroud having an inner surface facing the central axis, an outer surface opposite the inner surface and a thickness extending between said inner surface and outer surface; and
a leading seal extending from at least one of the interior surface of the housing and the outer surface of the shroud thereby forming a leading seal gap, and a trailing seal extending from at least one of the interior surface of the housing and the outer surface of the shroud thereby forming a trailing seal gap, said leading seal being closer to the leading edge of the blades than the trailing seal;
wherein the interior surface of the housing, the outer surface of the shroud, the leading seal, and the trailing seal define an annular cavity, the cavity being pressurized for maintaining the leading seal gap and the trailing seal gap at respective substantially uniform heights during inducer operation.
12. An inducer as set forth in claim 11 wherein at least one of the leading seal and the trailing seal has a plurality of axially spaced seal teeth.
13. An inducer as set forth in claim 12 wherein the axially spaced seal teeth are radially offset from each other.
14. An inducer as set forth in claim 11 wherein the rotor has a predetermined rotational operating speed at which a predetermined operating pressure is developed in the inducer between the inlet pressure and the outlet pressure, and wherein said outer surface of the shroud is substantially circular when the rotor is rotating at the predetermined rotational operating speed and the predetermined operating pressure is developed in the inducer.
15. An inducer as set forth in claim 14 wherein said outer surface of the shroud varies from round by no more than 0.30 inches when the rotor is rotating at the predetermined rotational operating speed and the predetermined operating pressure is developed in the inducer.
16. An inducer as set forth in claim 14 wherein the predetermined rotational operating speed of the inducer rotor is between about 6,000 rpm and about 30,000 rpm.
17. An inducer as set forth in claim 14 wherein the predetermined operating pressure is between 5 psi and about 1,500 psi.
18. An inducer as set forth in claim 11 wherein the interior surface of the housing includes a port for introducing fluid to the cavity thereby to pressurize the cavity.
19. An inducer as set forth in claim 18 wherein the port is supplied with fluid by a supply line from a source downstream from the outlet of the housing.
20. An inducer as set forth in claim 11 further comprising at least one seal intermediate the leading seal and the trailing seal.
21. An inducer as set forth in claim 11 wherein the shroud extends circumferentially between blades adjacent the blade tips and the shroud thickness varies from a predetermined minimum thickness located circumferentially between each adjacent pair of blade tips to a predetermined maximum thickness located adjacent each blade tip.