A compact, single shaft gas turbine gas generator uses a high pressure ratio dual-entry single stage centrifugal compressor, can combustors, and a radial inflow turbine with the compressor configured to achieve an overall pressure ratio of about 12:1 or greater and Mach Numbers less than or equal to
A compact, single shaft gas turbine gas generator uses a high pressure ratio dual-entry single stage centrifugal compressor, can combustors, and a radial inflow turbine with the compressor configured to achieve an overall pressure ratio of about 12:1 or greater and Mach Numbers less than or equal to about 1.4. The radial inflow turbine is configured to provide an expansion ratio of about 4:1 to about 5:1, to provide partially expanded combustion gases to a free-power turbine or an expansion nozzle, in a work-producing engine configuration. A ball bearing assembly in front of the compressor is used in conjunction with a thrust piston assembly to take up turbine thrust load, while a radial tilt pad bearing assembly is used in front of the turbine. A collector with scroll-shaped sector portions collects compressed air from an annular vaned diffuser, and respective crossover ducts channel the collected diffused compressed air from each sector portion to a plenum feeding can combustors. Bleed systems at each compressor inlet provide increased diffuser stability margins. Gas turbine engines configured with the above gas generator may provide 30% thermal efficiency or more in a rated power range of about 4 Mw or less.
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What is claimed is: 1. A high performance gas turbine gas generator comprising: a rotatable shaft defining an axial direction and a radial direction; a single compressor stage comprising a dual-entry high pressure ratio centrifugal compressor having a housing and a bladed impeller mounted on the sh
What is claimed is: 1. A high performance gas turbine gas generator comprising: a rotatable shaft defining an axial direction and a radial direction; a single compressor stage comprising a dual-entry high pressure ratio centrifugal compressor having a housing and a bladed impeller mounted on the shaft and defining with the housing a pair of opposed axially directed inlets and a single radially directed outlet; a combustor assembly operatively connected to receive compressed air from the centrifugal compressor outlet and configured for combusting fuel with the compressed air to produce combustion gases; a radial inflow turbine mounted on the shaft and operatively connected to receive combustion gases from the combustor assembly through a radially directed inlet and configured to partially expand the received combustion gases to drive the centrifugal compressor, the radial inflow turbine also configured to direct the partially expanded combustion gases through a generally axially directed turbine outlet, wherein the shaft is rotatably supported by a pair of bearing assemblies positioned at opposed axial ends of the centrifugal compressor, wherein the radial inflow turbine is mounted on a cantilevered portion of the shaft extending axially outboard of one of the bearing assemblies, wherein the centrifugal compressor inlets are further configured to provide, at a rated mass flow and speed (RPM), a maximum compressor inlet Mach Number of about 1.4 or less, and wherein the centrifugal compressor is further configured to provide at the rated speed and mass flow, a pressure ratio of about 12:1 or greater. 2. The gas generator of claim 1, wherein an expansion ratio across the radial inflow turbine is about 4:1 to about 5:1. 3. The gas generator as in claim 1, further including a bleed system for bleeding air through the compressor housing at locations adjacent each of the compressor inlets. 4. The gas turbine gas generator as in claim 1, wherein the combustor assembly includes a plurality of can combustors. 5. The gas generator as in claim 1, wherein essentially all the compressed air from the dual-entry compressor is received by the combustor assembly. 6. The gas generator as in claim 1, wherein the centrifugal compressor is configured to resist axial deformation of the impeller at the compressor outlet. 7. The gas generator as in claim 6, wherein the centrifugal compressor includes an impeller having a hub with a single integral wall adjacent the outlet, the wall being orthogonal to the axis and mounting axially opposed respective blade sets. 8. The gas generator as in claim 7, wherein the impeller hub is configured to operate at a speed of about 50,000 rpm at an air mass flow of about 5 kg/sec. 9. A gas turbine engine including the gas generator of claim 1 and having a thermal efficiency of about 30% or greater at a rated power of about 1 Mw to about 3 Mw. 10. An improved gas turbine gas generator of the type having a single stage centrifugal compressor mounted on a shaft rotatable about an axis, the compressor supplying compressed air to a combustor section, and a radial inflow turbine mounted on the shaft and configured for partially expanding gases formed by combusting fuel with the compressed air in the combustor section to drive the compressor and for releasing the partially expanded combustion gases for further work-producing expansion, the improvement comprising: the single stage centrifugal compressor comprising a dual-entry high pressure ratio centrifugal compressor having a housing, and a bladed impeller mounted on the shaft within the housing, the impeller defining with the housing a pair of spaced apart axially directed opposed inlets and a single radially directed outlet, wherein the compressor is configured to have a maximum inlet Mach Number of less than or equal to about 1.4 at rated speed and mass flow, wherein the compressor is configured to provide a pressure ratio of about 12:1 or greater to about 15:1, and wherein the compressor further includes means for bleeding air from each of the inlets. 11. The improved gas turbine gas generator of claim 10, wherein the dual-entry centrifugal compressor is mounted between a pair of bearing assemblies positioned proximate the respective compressor inlets, and wherein the radial turbine is mounted on a cantilevered portion of the shaft outboard of one of the bearing assembles. 12. The improved gas turbine gas generator of claim 11, wherein the bearing assembly adjacent the radial turbine comprises a radial tilt-pad bearing, and wherein the other bearing assembly comprises a ball bearing. 13. The improved gas turbine gas generator of claim 11, further including a thrust piston assembly configured to counteract axial thrust from the radial turbine. 14. The improved gas turbine gas generator as in claim 10, having an L/D ratio of about 1.25:1. 15. The improved gas turbine gas generator as in claim 10, further including an annular diffuser for diffusing compressed air received from the compressor outlet, a collector having plurality of scroll-shaped sector portions for collecting the diffused compressed air from the diffuser, and a like plurality of crossover ducts each connected to a respective scroll-shaped sector portion for channeling the collected diffused compressed air to the combustor section. 16. The improved gas turbine gas generator as in claim 15, wherein three collector scroll-shaped sector portions and three crossover ducts are provided. 17. The improved gas turbine gas generator as in claim 15, wherein the combustor includes a like plurality of can combustors angularly distributed about the axis and positioned between the crossover ducts. 18. The improved gas turbine gas generator as in claim 16, further including a compressor inlet casing for admitting air to both of the compressor inlets, wherein the inlet casing is positioned between two of the three angularly spaced crossover ducts. 19. A gas turbine engine including the gas turbine gas generator of claim 10 and a free-power turbine module configured to receive the partially expanded combustion gases from the gas generator. 20. A gas turbine engine including the gas turbine gas generator of claim 10 and propulsion nozzle apparatus configured to receive the partially expanded combustion gases from the gas generator.
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이 특허에 인용된 특허 (6)
Mowill R. Jan (Oslo NOX), Apparatus for mounting, and for maintaining running clearance in, a double entry radial compressor.
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