A gas turbine engine includes a fan shaft that drives a fan that has fan blades. An outer housing surrounds the fan. A bypass flow path is within the outer housing. A fan shaft support that supports the fan shaft defines a fan shaft support transverse stiffness. A gear system is connected to the fan shaft. The gear system includes a gear mesh that defines a gear mesh transverse stiffness. A flexible support which supports the gear system relative to a static structure defines a flexible support transverse stiffness. The flexible support transverse stiffness is less than 11% of the fan shaft support transverse stiffness. The flexible support transverse stiffness is less than 8% of the gear mesh transverse stiffness.

A reverse flow gas turbine engine has a low pressure (LP) spool and a high pressure (HP) spool arranged sequentially in an axial direction. The LP spool comprises an LP compressor disposed forward of an LP turbine and drivingly connected thereto via an LP compressor gear train. The HP spool comprises an HP compressor in flow communication with the LP compressor, and an HP turbine disposed forward of the HP compressor and drivingly connected thereto via an HP shaft.

A gas turbine engine includes a gear system that provides a speed reduction between a fan drive turbine and a fan rotor. Aspects of the gear system are provided with some flexibility. The fan drive turbine has a first exit area and rotates at a first speed. A second turbine section has a second exit area and rotates at a second speed, which is faster than said first speed. A performance quantity can be defined for both turbine sections as the products of the respective areas and respective speeds squared. A performance quantity ratio of the performance quantity for the fan drive turbine to the performance quantity for the second turbine section is relatively high.

A variable-cycle compressor includes: an axial-flow compressor, a flowpath downstream of the compressor, and at least one variable-cycle device operable to vary a choked flow capacity of the downstream flowpath. The compressor includes: a rotor having at least one rotor stage including a rotatable disk defining a rotor flowpath surface and an array of axial-flow rotor airfoils extending outward from the flowpath surface; at least one stator stage including a wall defining a stator flowpath surface, and an array of axial-flow stator airfoils extending away from the stator flowpath surface. At least one stage includes splitter airfoils alternating with the rotor or stator airfoils of the corresponding stage. At least one of a chord dimension of the splitter airfoils and a span dimension of the splitter airfoils is less than the corresponding dimension of the airfoils of the at least one stage.

A turbofan engine includes a fan section that drives air along a bypass flow path in a bypass duct. An epicyclic gear system in driving engagement with the fan shaft and has a gear mesh lateral stiffness and a gear mesh transverse stiffness. A gear system input to the gear system defines a gear system input lateral stiffness and a gear system input transverse stiffness. The gear system input lateral stiffness is less than 5% of the gear mesh lateral stiffness. A first performance quantity is defined as the product of a first speed squared and a first area and a second performance quantity is defined as the product of a second speed squared and a second area. A performance quantity ratio of a first performance quantity to a second performance quantity is between 0.5 and 1.5.

A centrifugal compressor for a turbocharger includes an inlet-adjustment mechanism in an air inlet for the compressor, operable to move between an open position and a closed position in the air inlet. Movement of the inlet-adjustment mechanism from the open position to the closed position is effective to shift the compressor's surge line to lower flow rates. The compressor includes a diffuser extending between an exducer of the compressor wheel and a volute for collecting pressurized air from the compressor. The diffuser is defined between first and second walls that diverge from each other in a radially outwardly direction through the diffuser. The divergent-wall diffuser enhances the shift of the surge line to lower flow rates when the inlet-adjustment mechanism is put in the closed position.

A vibrorotational fluid flow actuator includes: a first vibrorotational component comprising a first body including an axis, a plurality of first legs extending from a bottom surface of first body in a direction of and at an angle to the axis, and a plurality of first blades extending from a respective side of the first body in a direction perpendicular to the axis, wherein when the first vibrorotational component is placed on a chassis, vibration of the chassis induces rotation of the body such that the blades and body rotate about the axis of the body thereby inducing fluid flow in a fluid surrounding the actuator.

A gas turbine engine includes a gear system that provides a speed reduction between a fan drive turbine and a fan rotor. Aspects of the gear system are provided with defined flexibility. The fan drive turbine has a first exit area and rotates at a first speed. A second turbine section has a second exit area and rotates at a second speed, which is faster than said first speed. A performance quantity can be defined for both turbine sections as the products of the respective areas and respective speeds squared. A performance quantity ratio of the performance quantity for the fan drive turbine to the performance quantity for the second turbine section is between 0.5 and 1.5.

The invention enables an adequate crankcase negative pressure in an internal combustion engine, in all operating ranges to the extent possible and using a suction device for the crankcase ventilation of an internal combustion engine, which suction device is equipped with a housing, a controllable electric motor and a compressor for conveying crankcase gas, which compressor is driven by the electric motor, the compressor having connection points for a crankcase ventilation line, such that the crankcase pressure of the internal combustion engine is controllable by controlling the electric motor.

A gas turbine engine according to an example of the present disclosure includes, among other things, a fan shaft driving a fan having fan blades. The fan delivers airflow to a bypass duct. A fan shaft support supports the fan shaft and defines a support transverse stiffness. A gear system is connected to the fan shaft and includes a gear mesh defining a gear mesh transverse stiffness and a reduction ratio greater than 2.3. A gear system input is connected to the gear system and defines a gear system input lateral stiffness. A flexible support supports the gear system and defines a flexible support transverse stiffness. The gear system input lateral stiffness is less than 5% of the gear mesh lateral stiffness and the flexible support transverse stiffness is less than 20% of the fan shaft support transverse stiffness.