Abstract: A gas turbine engine includes a main engine compressor section. A booster compressor changes a pressure of airflow received from the main engine compressor section to a pressure desired for a pneumatic system. The booster compressor is configured to operate at airflow conditions greater than a demand of the pneumatic system. An exhaust valve controls airflow between an exhaust outlet and an outlet passage to the pneumatic system. The exhaust valve is operable to exhaust airflow from the booster compressor in excess of the demand of the pneumatic system. A bleed air system for a gas turbine engine and a method of controlling engine bleed airflow are also disclosed.

Abstract: A gas turbine engine includes a plurality of rotatable components housed within a main compressor section and a turbine section. A cooling system is connected to tap air from said main compressor section. A first tap is connected to a first heat exchanger. The first heat exchanger is connected to a cooling compressor for raising a pressure of the tapped air downstream of the first heat exchanger. A second heat exchanger is downstream of the cooling compressor, and a connection is downstream of the second heat exchanger for delivering air to a bearing compartment. A connection intermediate the cooling compressor and the second heat exchanger delivers cooling air to at least one of the rotatable components.

Abstract: A gas turbine engine comprises a main compressor section having a high pressure compressor with a downstream most end, and more upstream locations. A turbine section has a high pressure turbine. A first tap taps air from at least one of the more upstream locations in the main compressor section, passing the tapped air through a first heat exchanger and then to a cooling compressor. A second tap taps air from a location closer to the downstream most end than the location of the first tap, and the first and second taps mix together and are delivered into the high pressure turbine. The cooling compressor is positioned downstream of the first heat exchanger, and upstream of a location where air from the first and second taps mix together.

Abstract: A gas turbine engine comprises a main compressor section having a high pressure compressor with a downstream discharge, and more upstream locations. A turbine section has a high pressure turbine. A tap taps air from at least one of the more upstream locations in the compressor section, passes the tapped air through a heat exchanger and then to a cooling compressor. The cooling compressor compresses air downstream of the heat exchanger, and delivers air into the high pressure turbine. An intercooling system for a gas turbine engine is also disclosed.

Abstract: A gas turbine engine includes, among other things, a fan section including a fan rotor, a gear train defined about an engine axis of rotation, a first nacelle which at least partially surrounds a second nacelle and the fan rotor, the fan section configured to communicate airflow into the first nacelle and the second nacelle, a first turbine, and a second turbine followed by the first turbine. The first turbine is configured to drive the fan rotor through the gear train. A static structure includes a first engine mount location and a second engine mount location.

Abstract: A gas turbine engine comprises a main compressor section having a high pressure compressor, and at least one more upstream compressor. A turbine section has a high pressure turbine. A tap line taps air from at least one of the more upstream compressors in the compressor section, passes the tapped air through a heat exchanger and then to a cooling compressor. The cooling compressor compresses air downstream of the heat exchanger, and delivers air into the high pressure turbine. A bypass valve is positioned downstream of the main compressor section, and upstream of the heat exchanger. The bypass valve selectively delivers air directly to the cooling compressor without passing through the heat exchanger under certain conditions. An intercooling system is also disclosed.

Abstract: A gas turbine engine includes a core housing that includes an inlet case and an intermediate case that respectively provide an inlet case flow path and an intermediate case flow path. A first shaft supports a low pressure compressor section that is arranged axially between the inlet case flow path and the intermediate case flow path. A first bearing supports the first shaft relative to the inlet case. A second bearing supports a second shaft relative to the intermediate case. A low pressure compressor hub is mounted to the first shaft. The low pressure compressor hub extends to the low pressure compressor section between the first bearing and the second bearing.

Abstract: A gas turbine engine comprises a compressor section and a turbine section, with the turbine section having a first stage blade row and a downstream blade row. A higher pressure tap is tapped from a higher pressure first location in the compressor. A lower pressure tap is tapped from a lower pressure location in the compressor which is at a lower pressure than the first location. The higher pressure tap passes through a heat exchanger, and then is delivered to cool the first stage blade row in the turbine section. The lower pressure tap is delivered to at least partially cool the downstream blade row.

Abstract: A gas turbine engine comprises a main compressor section having a high pressure compressor with a downstream discharge, and more upstream locations. A turbine section has a high pressure turbine. A tap taps air from at least one of the more upstream locations in the compressor section, passes the tapped air through a heat exchanger and then to a cooling compressor. The cooling compressor compresses air downstream of the heat exchanger, and delivers air into the high pressure turbine. The cooling compressor is connected to be driven with at least one rotor in the main compressor section. A source of pressurized air is selectively sent to the cooling compressor to drive a rotor of the cooling compressor to rotate, and to in turn drive the at least one rotor of the main compressor section at start-up of the gas turbine engine. An intercooling system is also disclosed.

Abstract: An auxiliary power unit may comprise a twin centrifugal compressor including a first blade. A turbine may be disposed aft of the twin centrifugal compressor. The turbine may include a second blade. The first blade comprises a first material and the second blade comprises a second material. The first material may the same as the second material. The twin centrifugal compressor may include forward centrifugal compressor and an aft centrifugal compressor disposed aft of the forward centrifugal compressor.

Abstract: The present disclosure provides systems and methods related to thermal management systems for gas turbine engines. For example, a thermal management system comprises a thermally neutral heat transfer fluid circuit, a first heat exchanger disposed on the fluid circuit, and a second heat exchanger disposed on the fluid circuit.

Abstract: A gas turbine engine comprises a first compressor, a second compressor, a starter generator and a clutch. The starter generator is coupled to the first compressor. The clutch selectively couples the second compressor and the first compressor. The clutch is disposed between a first shaft and a second shaft to engage the first shaft with the second shaft at rest. A flyweight system is engaged with the clutch mechanism to permit freewheeling of the first shaft relative to the second shaft when subject to rotational motion beyond a threshold speed. A method for starting a gas turbine engine comprises engaging a low pressure compressor with a high pressure compressor utilizing a clutch, rotating the low pressure compressor and the high pressure compressor utilizing a starter generator coupled to the low pressure compressor, igniting the gas turbine engine, and disengaging the clutch at an operational speed of the gas turbine engine.

Abstract: A compressor section for use in a gas turbine engine comprises a compressor rotor having a hub and a plurality of blades extending radially outwardly from the hub and an outer housing surrounding an outer periphery of the blades. A tap taps air at a radially outer first location, passing the tapped air through a heat exchanger, and returning the tapped air to an outlet at a second location which is radially inward of the first location, to provide cooling air adjacent to the hub. A gas turbine engine is also disclosed.

Abstract: A method comprises the steps of modifying an existing engine which includes a high pressure compressor driven by a high pressure turbine and a low pressure turbine to drive a low pressure compressor. The modifying step includes utilizing the high pressure compressor as a low pressure compressor in a modified gas turbine engine, and designing and incorporating a new high pressure compressor downstream of the low pressure compressor section in the modified engine, such that a portion of the design of the existing engine is utilized in the modified engine. A gas turbine engine is also disclosed.

Abstract: A gas turbine engine comprises a main compressor section having a high pressure compressor with a downstream most end, and more upstream locations. A turbine section has a high pressure turbine. A first tap taps air from at least one of the more upstream locations in the main compressor section, passes the tapped air through a heat exchanger and then to a cooling compressor. The cooling compressor compresses air downstream of the heat exchanger. A second tap taps air from a location closer to the downstream most end than the location(s) of the first tap. The first and second tap mix together and are delivered into the high pressure turbine. An intercooling system for a gas turbine engine is also disclosed.

Abstract: One exemplary embodiment of this disclosure relates to a gas turbine engine. The engine includes a first rotor disk, a second rotor disk, and a circumferentially segmented seal. The segmented seal engages the first rotor disk and the second rotor disk. The segmented seal further includes a fore surface contacting the first disk, an aft surface contacting the second disk, and a radially outer surface. Further, (1) the aft surface and (2) one of the fore surface and the radially outer surface include perforations to allow fluid to flow through the interior of the segmented seal.

Abstract: A gas turbine engine comprises a compressor section and a turbine section, with the turbine section having a first stage blade row and a downstream blade row. A higher pressure tap is tapped from a higher pressure first location in the compressor. A lower pressure tap is tapped from a lower pressure location in the compressor which is at a lower pressure than the first location. The higher pressure tap passes through a heat exchanger, and then is delivered to cool the first stage blade row in the turbine section. The lower pressure tap is delivered to at least partially cool the downstream blade row.

Abstract: A gas turbine engine includes a housing includes an inlet case and an intermediate case that respectively provide an inlet case flow path and an intermediate case flow path. A rotor is connected to the hub and supports a compressor section. The geared architecture includes an epicyclic gear train. A fan is rotationally driven by the geared architecture. First and second bearings support the shaft relative to the intermediate case and the inlet case, respectively. The radially inner boundary of the core inlet is at a location of a core inlet stator and the radially inner boundary of the compressor section inlet is at a location of the first stage low-pressure compressor rotor.

Abstract: A gas turbine engine comprises a main compressor section having a high pressure compressor with a downstream most end, and more upstream locations. A turbine section has a high pressure turbine. A first tap taps air from at least one of the more upstream locations in the main compressor section, passes the tapped air through a heat exchanger and then to a cooling compressor. The cooling compressor compresses air downstream of the heat exchanger. A second tap taps air from a location closer to the downstream most end than the location(s) of the first tap. The first and second tap mix together and are delivered into the high pressure turbine. An intercooling system for a gas turbine engine is also disclosed.

Abstract: A gas turbine engine comprises a main compressor section having a high pressure compressor with a downstream discharge, and more upstream locations. A turbine section has a high pressure turbine. A tap taps air from at least one of the more upstream locations in the compressor section, passes the tapped air through a heat exchanger and then to a cooling compressor. The cooling compressor compresses air downstream of the heat exchanger, and delivers air into the high pressure turbine. The cooling compressor is connected to be driven with at least one rotor in the main compressor section. A source of pressurized air is selectively sent to the cooling compressor to drive a rotor of the cooling compressor to rotate, and to in turn drive the at least one rotor of the main compressor section at start-up of the gas turbine engine. An intercooling system is also disclosed.