Centrifugal compressor with a splitter shroud in flow path

A gasifier spool assembly for a gas turbine engine comprising:

• a gasifier turbine driven by motive fluid, a low inertia centrifugal compressor having an impeller with a hub, a shaft connected to said turbine, said hub having means for connection to said shaft, a plurality of separate free formed blades on said hub each having a root portion integrally connected to the outer periphery of the hub and defining a flow passage with an adjacent blade, each of said blades including a free rear edge portion directed essentially radially outwardly of the hub and being circumferentially spaced with respect to an adjacent blade free rear edge portion to define a rear opening through the impeller at the hub from each of the flow passages to reduce windage losses during impeller operation, a flow splitter ring formed continuously circumferentially around the impeller being integrally formed with each of the separate blades, said flow splitter ring having an inlet edge located at the transition of axial to radial flow through the impeller and including an outlet edge located adjacent the outer periphery of said blades, said flow splitter ring interconnecting each of the separate blade members to prevent blade flutter during impeller rotation, said splitter ring being located along a streamline in the flow passage between each of the separate blades and at a point forwardly of the rear plane of the impeller, said splitter ring having a cross section thickness, height and width to minimize the polar moment of inertia of said impeller whereby the gasifier spool assembly can be operated at an idle speed between 35%-40% of the spool design speed while maintaining engine response.

A low inertia centrifugal rotary impeller of unitary construction for association with a gasifier turbine of a gas turbine engine gasifier spool and wherein the gasifier turbine is driven by motive fluid to accelerate the impeller comprising:

• an impeller hub portion, means for connecting said hub portion to the gasifier turbine shaft, a plurality of circumferentially spaced, separate free formed blades on said hub each having a root portion integrally connected to the outer periphery of said hub and defining a flow passage with an adjacent blade, each of said blades including an inlet inducer with an inlet edge, each of said blades having a radial impeller portion with a free rear edge directed radially outwardly of the hub and being circumferentially spaced with respect to an adjacent blade free rear edge portion to define a rear opening through the impeller at the hub from each of the flow passages to reduce windage losses during impeller operation, a splitter ring formed continuously circumferentially around the impeller being integrally formed with each of the separate blades at the periphery of said radial impeller portions, said splitter ring having an inlet edge located radially outwardly of the tip of the inlet edge and including an outlet edge located adjacent the outer periphery of the circumferentially spaced blades of the impeller, said splitter ring interconnecting each of the radial impeller portions of said separate blades to prevent blade flutter therebetween during impeller rotation, said splitter ring being located along a streamline in the flow passage between each of the separate blades and at a point forwardly of the rear plane of the impeller layer, said splitter ring having a cross section thickness, height and width to minimize the polar moment of inertia of said impeller whereby the gasifier spool assembly can be operated at an idle speed between 35%-40% of the spool design speed while maintaining engine response.