Abstract: A system for determining properties of fuel supplied to an internal combustion (IC) engine and for adjusting operations of the IC engine based on the determined properties. The system includes an air-flow throttle configured to control the air supplied to the IC engine; a fuel-flow throttle configured to control the fuel supplied to the IC engine; and an engine control module (ECM) configured to receive readings from and control operation of the throttles. The ECM is configured to perform a fuel-air determination program where the ECM determines a percent-error air-to-fuel ratio (AF) based on a true AF ratio compared to an ideal AF ratio. The ECM is configured to perform a fuel property determination and adjustment program in which the ECM is configured to adjust operations of the IC engine based on a fuel property value determined using the percent-error AF ratio.

Abstract: A method of manufacturing a multistage axial-centrifugal compressor for a gas turbine engine and a multistage axial-centrifugal compressor that includes a series of axial compressor stages each having a rotor mounted to a common shaft positioned upstream from a centrifugal compressor stage mounted to the common shaft. The method includes determining an operational rotor tip speed for each of the axial stages. The method includes comparing the operational rotor tip speed to a threshold range value and determining to machine an airfoil of the rotor for at least one of the axial stages by an arbitrary manufacturing approach based on the operational rotor tip speed as greater than the threshold range value. The method includes determining to machine an airfoil of the rotor for at least one of the axial stages by a flank manufacturing approach based on the operational rotor tip speed as less than the threshold range value.

Abstract: A method of manufacturing a multistage axial-centrifugal compressor for a gas turbine engine and a multistage axial-centrifugal compressor that includes a series of axial compressor stages each having a rotor mounted to a common shaft positioned upstream from a centrifugal compressor stage mounted to the common shaft. The method includes determining an operational rotor tip speed for each of the axial stages. The method includes comparing the operational rotor tip speed to a threshold range value and determining to machine an airfoil of the rotor for at least one of the axial stages by an arbitrary manufacturing approach based on the operational rotor tip speed as greater than the threshold range value. The method includes determining to machine an airfoil of the rotor for at least one of the axial stages by a flank manufacturing approach based on the operational rotor tip speed as less than the threshold range value.

Abstract: A compressor includes a housing, a rotor, an impeller, and a ported shroud. The rotor is mounted within the housing, and has a first leading edge and a first trailing edge. The rotor is operable, upon rotation thereof, to compress air and to discharge the air in an approximately axial direction. The impeller is mounted within the housing, and has a second leading edge and a second trailing edge. The impeller is operable, upon rotation thereof, to receive the air discharged from the rotor, to further compress the air, and to discharge the air in an approximately radial direction. The shroud at least partially surrounds the impeller. The shroud has an opening therein to at least facilitate allowing the air to travel upstream of the opening.

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 gas turbine engine combustor includes a plurality of main fuel injector assemblies, and a plurality of pilot fuel injector assemblies, that are arranged and configured to reduce exhaust gas emissions during engine operation. The plurality of main fuel injector assemblies are arranged in a substantially circular pattern of a first radius, and each includes an outlet port having a first divergence angle. The plurality of pilot fuel injector assemblies are arranged in a substantially circular pattern of a second radius. Each pilot fuel injector assembly is disposed between at least two main fuel injector assemblies, and each includes an outlet port having a second divergence angle.

Abstract: A gas turbine engine combustor includes a plurality of main fuel injector assemblies, and a plurality of pilot fuel injector assemblies, that are arranged and configured to reduce exhaust gas emissions during engine operation. The plurality of main fuel injector assemblies are arranged in a substantially circular pattern of a first radius, and each includes an outlet port having a first divergence angle. The plurality of pilot fuel injector assemblies are arranged in a substantially circular pattern of a second radius. Each pilot fuel injector assembly is disposed between at least two main fuel injector assemblies, and each includes an outlet port having a second divergence angle.

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 a housing, a rotor, an impeller, and a ported shroud. The rotor is mounted within the housing, and has a first leading edge and a first trailing edge. The rotor is operable, upon rotation thereof, to compress air and to discharge the air in an approximately axial direction. The impeller is mounted within the housing, and has a second leading edge and a second trailing edge. The impeller is operable, upon rotation thereof, to receive the air discharged from the rotor, to further compress the air, and to discharge the air in an approximately radial direction. The shroud at least partially surrounds the impeller. The shroud has an opening therein to at least facilitate allowing the air to travel upstream of the opening.

Abstract: A gas turbine engine combustor includes a plurality of main fuel injector assemblies, and a plurality of pilot fuel injector assemblies, that are arranged and configured to reduce exhaust gas emissions during engine operation. The plurality of main fuel injector assemblies are arranged in a substantially circular pattern of a first radius, and each includes an outlet port having a first divergence angle. The plurality of pilot fuel injector assemblies are arranged in a substantially circular pattern of a second radius. Each pilot fuel injector assembly is disposed between at least two main fuel injector assemblies, and each includes an outlet port having a second divergence angle.

Abstract: A system is provided for aerodynamically coupling air flow from a centrifugal compressor to an axial combustor. The system includes a diffuser, a deswirl assembly, combustor inner and outer annular liners, a combustor dome, and a curved annular plate. The diffuser has an inlet that communicates with the centrifugal compressor, an outlet, and a flow path that extends radially outward. The deswirl assembly has an inlet that communicates with the diffuser outlet to receive air flowing in a radially outward direction, an outlet, and a flow path configured to redirect the air in a radially inward and axial direction through the deswirl assembly outlet at an angle toward a longitudinal axis. The curved annular plate is coupled to combustor inner and outer annular liner upstream ends to form a combustor subplenum therebetween and has a first opening and a second opening formed therein, the first opening aligned with the deswirl assembly outlet to receive air discharged therefrom.

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.