Abstract: A compressor includes a diffuser, a recirculation duct, and a flow control valve. The recirculation duct has an inlet in fluid communication with the air outlet of the diffuser, and an outlet in fluid communication with the air inlet of the diffuser. The flow control valve is selectively moveable between open and closed positions, to thereby fluidly couple and isolate, respectively, the recirculation duct inlet and outlets. During operation of the compressor, the flow control valve may be opened, which circulates a portion of the compressed air discharged from the diffuser air outlet back to the diffuser air inlet. The air that is circulated back to the diffuser air inlet reduces the effective area of the diffuser air inlet, thereby increasing the surge margin of the compressor.

Abstract: A radial diffuser comprises a housing, a plurality of diffuser vanes, and a plurality of integral service vanes. The housing includes an air inlet and an air outlet, and defines a radial section extending radially outward from the air inlet, an axial section extending axially to the air outlet, and a transition including a bend and extending between the radial and axial sections. The diffuser vanes are coupled to the housing, and are disposed in, and define diffusion flow passages. The integral service vanes are coupled to the housing, extend around the bend, and define transition flow passages, each in fluid communication with at least one diffusion flow passage. At least some of the integral service vanes include a service passage extending therethrough and configured to allow a service conduit to extend therethrough without crossing either a diffusion flow passage or a transition flow passage.

Abstract: A radial diffuser comprises a housing, a plurality of diffuser vanes, and a plurality of integral service vanes. The housing includes an air inlet and an air outlet, and defines a radial section extending radially outward from the air inlet, an axial section extending axially to the air outlet, and a transition including a bend and extending between the radial and axial sections. The diffuser vanes are coupled to the housing, and are disposed in, and define diffusion flow passages. The integral service vanes are coupled to the housing, extend around the bend, and define transition flow passages, each in fluid communication with at least one diffusion flow passage. At least some of the integral service vanes include a service passage extending therethrough and configured to allow a service conduit to extend therethrough without crossing either a diffusion flow passage or a transition flow passage.

Abstract: A compressor includes an enhanced vaned shroud and is configured such that the flow area ratio is equivalent to that of a conventional, non-vaned shroud. The vaned shroud includes a plurality of airfoils that vary in thickness to obtain desired vibrational mode shapes and natural frequencies. A stiffening ring of limited axial extent is coupled to, and between, the airfoils, and the shroud is manufactured with a section of constant radius.

Abstract: Cooling air to the blades and disks of a gas turbine may be modulated to provide a variable turbine cooling flow. A bellows may be extended by providing a high pressure compressor discharge flow to an interior of the bellows. The bellows may be compressed when the interior of the bellows communicates with ambient pressure air. The extension/compression of the bellows moves an arm over orifices in a cooling air flow path. The pressure inside of the bellows is metered to move the arm over at least one orifice, thereby restricting cooling air flow when the engine is running at low power. The pressure inside of the bellows is metered to move the arm to uncover all of the slots to provide maximum cooling flow when the engine is running at high power. The resulting variable cooling flow system results in less need for cooling air at low powers, thus reducing engine fuel consumption.

Abstract: A passive feedback-controlled regulator and method for regulating gas turbine bleed air is provided, which automatically regulates the flow of coolant air directed to the turbine vanes, blades, and other hot section components based on the inherent differential pressure between the diffused compressor discharge pressure and the compressor impeller exit air. The differential pressure used to operate the regulator is a measure of the turbine mass flow rate, and, therefore is a measure of the instantaneous engine coolant flow requirement.

Abstract: A bleed air buffer seal arrangement is provided for improved buffer sealing of oil sump seals in a gas turbine engine. In a multiple spool gas turbine engine, bleed air for buffer sealing is obtained through an annular bleed slot or annular array of bleed ports formed in the impeller shroud of a high pressure centrifugal impeller at a location spaced aft or downstream from the leading edge thereof. Bleed air from this location exhibits significant pressure at low engine power conditions to provide satisfactory buffer sealing, without subjecting sump seals to excess pressure or temperature at high engine power conditions.

Abstract: A centrifugal compressor impeller for gas turbine engines designed to efficiently operate at both part-speed and full speed design points includes slanted vanes in a secondary air inlet to the impeller. The vanes are tangentially slanted in the direction of rotation of the impeller to preferentially augment airflow into the impeller at maximum speed, while at part-speed discouraging airflow out of its impeller through the secondary inlet.

Abstract: An improved centrifugal compressor for use in gas turbine engines includes a secondary air flow inlet in the compressor shroud at a location downstream of the inducer, with passive elements in the secondary air inlet for effectively preventing flow out of the secondary air inlet from the compressor impeller at part speed design operation, while augmenting and enhancing flow of secondary air flow into the compressor impeller at maximum design speed operation of the compressor impeller.

Abstract: A fluid compressor control and operation method wherein a tangential velocity is imparted to all or only a selected part of fluid flowing to a rotating impeller of the compressor. In a preferred embodiment, the impeller is of centrifugal radial flow configuration with an inlet duct effecting inlet flow radially inwardly, and then axially to the impeller. The compressor includes a plurality of axially elongate guide vanes disposed annularly of the inlet and axially moveable relatively thereof into and out of the inlet fluid flow.

Abstract: A fluid compressor including a rotating impeller and apparatus inhibiting fluid surging. The surge inhibiting apparatus includes a multitude of guide vanes circumscribing an inlet of the compressor. Movement of the guide vanes with respect to fluid flowing to the compressor is effective to inhibit fluid surging. A combustion turbine including such a fluid compressor, and a vehicle powered by such an engine are also disclosed.