Ceramic turbine volute

Abstract

A gas turbine and nozzle system is provided that includes a radial inflow turbine rotor and a volute providing a flow path to deliver a pressurized gas to a circumference of the radial turbine rotor. The volute incorporates a shape which substantially conforms to a radial turbine shroud contour. The volute includes at least first and second parts. A mating surface between the first and second parts is substantially aligned with a direction of pressurized gas flow in the volute.

What is claimed is: 
     
         1 . A gas turbine and nozzle system, comprising:
 a radial inflow turbine rotor; and   a volute providing a flow path to deliver a pressurized gas to a circumference of the radial turbine rotor, wherein the volute incorporates a shape which substantially conforms to a radial turbine shroud contour; wherein the volute comprises at least first and second parts and wherein a mating surface between the first and second parts is substantially aligned with a direction of pressurized gas flow in the volute.   
     
     
         2 . The system of  claim 1 , wherein the first and second parts operatively engage each other along a plane which is normal (perpendicular) to the first turbine axis, wherein the first and second parts comprise a ceramic material, wherein the first and second parts are clamped between rings, and wherein the first and second parts are made from a ceramic material whose thermal conductivity is relatively high compared to first and second thermal barriers, and wherein the first and second parts and the first and second thermal barriers are stacked in an axial plane and share a common first turbine axis. 
     
     
         3 . The system of  claim 2 , wherein the first and second parts each have a precision flat mating surface that, when combined, form a closed volume around the tip of the radial turbine rotor. 
     
     
         4 . The system of  claim 1 , further comprising first and second thermal barriers corresponding respectively to the first and second parts of the volute, wherein the first thermal barrier is positioned between the first part and a first bearing core, wherein the second thermal barrier is positioned between the second part and a clamp tube and/or a second bearing core, and wherein the first thermal barrier has a thermal conductivity lower than a thermal conductivity of the first part and/or the first bearing core and the second thermal barrier has a thermal conductivity lower than a thermal conductivity of the second part and/or the clamp tube and/or second bearing core. 
     
     
         5 . The system of  claim 4 , wherein at least one of the first and second barriers comprises a channel feature to maintain an alignment of the first and second volute parts. 
     
     
         6 . The system of  claim 1 , wherein mating surfaces of the first and second volute parts comprise one or more holes, a dowel pin in each hole, and a slot on an opposing mating surface to receive the dowel pin to enable thermal expansion and contraction of each of the first and second parts while maintaining substantially a gas seal between the first and second parts. 
     
     
         7 . The system of  claim 4 , wherein the first and second parts and first and second thermal barriers are clamped together along the common turbine axis by the clamp tube and a bellows and wherein planes of each of the mating surfaces of the first and second parts and first and second thermal barriers are perpendicular to the first turbine axis. 
     
     
         8 . The system of  claim 1 , further comprising:
 first and second thermal barriers engaging respectively the first and second parts of the volute; and   a flexible corrugated bellows duct with a relatively low internal pressure and relatively high pressure on an outer radius of the bellows duct, and wherein the pressure differential generates a pneumatic pressure force which loads the first and second volute parts in compression between the first and second thermal barriers.   
     
     
         9 . The system of  claim 1 , wherein the volute has internal and external surfaces, wherein the internal surface defines a volume filled with the pressurized gas feeding the turbine rotor, and wherein the external surface experiences a relatively static gas pressure higher than that on the internal surface, thereby loading the volute in compression. 
     
     
         10 . The system of  claim 2 , wherein the ceramic material is silicon carbide, silicon nitride, or an oxide of aluminum, silicon, calcium, phosphorous, or lithium. 
     
     
         11 . A gas turbine and nozzle system, comprising:
 a radial inflow turbine rotor;   a volute providing a flow path to deliver a pressurized gas to a circumference of the radial turbine rotor, wherein the volute comprises at least first and second parts; and   first and second thermal barriers corresponding respectively to the first and second parts of the volute, wherein the first thermal barrier is positioned between the first part and a first bearing core and wherein the second thermal barrier is positioned between the second part and a second bearing core.   
     
     
         12 . The system of  claim 11 , wherein the volute incorporates a shape which substantially conforms to a radial turbine shroud contour, wherein a mating surface between the first and second parts is substantially aligned with a direction of pressurized gas flow in the volute, wherein the first and second parts operatively engage each other along a plane which is normal (perpendicular) to the first turbine axis, wherein the first and second parts comprise a ceramic material, wherein the first and second parts are clamped between rings, and wherein the first and second parts are made from a ceramic material whose thermal conductivity is relatively high compared to the first and second thermal barriers, wherein the ceramic material in the first and second parts is silicon carbide, silicon nitride, or an oxide of aluminum, silicon, calcium, phosphorous, or lithium, and wherein the first and second parts and the first and second clamped rings are stacked in an axial plane and share a common first turbine axis. 
     
     
         13 . The system of  claim 12 , wherein the first and second parts each have a precision flat mating surface that, when combined, form a closed volume around the tip of the radial turbine rotor. 
     
     
         14 . The system of  claim 11 , wherein the first thermal barrier has a thermal conductivity lower than a thermal conductivity of the first part and/or the first bearing core and the second thermal barrier has a thermal conductivity lower than a thermal conductivity of the second part and/or the clamp tube and/or second bearing core. 
     
     
         15 . The system of  claim 14 , wherein at least one of the first and second barriers comprises a channel feature to maintain an alignment of the first and second volute parts. 
     
     
         16 . The system of  claim 11 , wherein mating surfaces of the first and second volute parts comprise one or more holes, a dowel pin in each hole, and a slot on an opposing mating surface to receive the dowel pin to enable thermal expansion and contraction of each of the first and second parts while maintaining substantially a gas seal between the first and second parts. 
     
     
         17 . The system of  claim 14 , wherein the first and second parts and first and second thermal barriers are clamped together along the common turbine axis by the clamp tube and a bellows and wherein planes of each of the mating surfaces of the first and second parts and first and second thermal barriers are perpendicular to the first turbine axis. 
     
     
         18 . The system of  claim 11 , further comprising:
 a flexible corrugated bellows duct with a relatively low internal pressure and relatively high pressure on an outer radius of the bellows duct, and wherein the pressure differential generates a pneumatic pressure force which loads the first and second volute parts in compression between the first and second thermal barriers.   
     
     
         19 . The system of  claim 11 , wherein the volute has internal and external surfaces, wherein the internal surface defines a volume filled with the pressurized gas feeding the turbine rotor, and wherein the external surface experiences a relatively static gas pressure higher than that on the internal surface, thereby loading the volute in compression. 
     
     
         20 . A method, comprising:
 inserting a radial inflow turbine rotor, through a turbine exit end of a pressure bearing housing and through a first portion of a volute, a radial inflow turbine rotor; and   thereafter engaging the first portion of the volute with a second portion of the volute to enclose the radial inflow turbine rotor between the first and second volute portions.   
     
     
         21 . The method of  claim 20 , wherein, when the radial inflow turbine rotor is inserted through the first portion of the volute, the radial inflow rotor is aligned with and in close proximity to an integral turbine back plate.