A contra-rotating compressor includes a first shaft assembly disposed in a housing, the first shaft assembly including an outer shaft, and a first plurality of impellers coupled to the outer shaft, wherein the outer shaft includes a final stage that includes a final impeller of the first plurality of impellers. The compressor further includes a second shaft assembly disposed in the housing and rotatable about the longitudinal axis that has a second plurality of impellers, a first pair of annular seals between the final stage and an inner surface of the housing that are configured to permit relative rotation between the final stage and the housing, and a third annular seal positioned between the outer surface of the final stage and an inner surface of the second shaft assembly that is configured to permit contra-rotation between the final stage and the second shaft assembly.

An electric propulsion system for an aircraft includes a nacelle and an electric machine. The electric machine includes a stator positioned in the nacelle, and a rotor and fan assembly positioned in a primary flow path through the nacelle. The rotor and fan assembly includes a cylindrical fan shroud, a plurality of rotor magnets positioned on an outer surface of the fan shroud, and a fan hub mounted on a central support shaft via one or more bearings. A plurality of fan blades extend between an inner surface of the fan shroud and an outer surface of the fan hub. The rotor magnets may be loaded in compression in a radial direction when the rotor and fan assembly is at rest. The fan blades may be pre-stressed in a radial direction when the rotor and fan assembly is at rest.

A dryer includes a hollow casing, a fan disposed inside the casing so as to cause air to be introduced into the casing and to be discharged therefrom, a heater disposed inside the casing to heat the air introduced into the casing by the fan, and a discharge tube including an inlet into which the air is introduced, and an outlet from which the air is discharged. The fan includes a first fan and a second fan, which rotate in opposite directions about an imaginary axis shared by the first and second fans. A discharge amount or a discharge rate can be controlled in a stepwise manner. The discharge tube is disposed inside the casing so as to be rotated in at least one direction, thereby diffusely discharging drying air to a region desired to be dried.

A gas turbine is provided, the gas turbine engine including a turbomachine having an inlet splitter defining in part an inlet to a working gas flowpath and a fan duct splitter defining in part an inlet to a fan duct flowpath. The gas turbine engine also includes a primary fan driven by the turbomachine defining a primary fan tip radius R1, a primary fan hub radius R2, and a primary fan specific thrust rating TP; and a secondary fan downstream of the primary fan and driven by the turbomachine, the secondary fan defining a secondary fan tip radius R3, a secondary fan hub radius R4, and a secondary fan specific thrust rating TS; wherein the gas turbine engine defines an Effective Bypass Area, and wherein a ratio of R1 to R3 equals

[00001]$\frac{R_1}{R_3}=\sqrt{\left(EFP\right)\frac{\left(1-{\mathrm{RqR}}_{\mathrm{Sec}.-\mathrm{Fan}}^2\right)}{\left(1-{\mathrm{RqR}}_{\mathrm{Prim}.-\mathrm{Fan}}^2\right)}\left(\frac{T_P}{T_S}\right)\left(EBA\right)}.$

A technique facilitates movement of fluids with reduced component loading by utilizing opposed axial forces. The system for moving fluid may be in the form of a gas compressor, liquid pump, or other device able to pump or otherwise move fluid from one location to another. According to an embodiment, the system includes rotor sections which are combined with pumping features. The rotor sections are disposed radially between corresponding inner and outer stator sections which may be powered to cause relative rotation of inner and outer rotor sections in opposite directions. The rotors and corresponding pumping features are configured to move fluid in opposed axial directions toward an outlet section so as to balance axial forces and thus reduce component loading, e.g. thrust bearing loading.

A vaneless contra-rotating compressor with multiple contra-rotating interfaces and application of the vaneless contra-rotating compressor is provided, which includes at least two vaneless contra-rotating interfaces. For each of the at least two contra-rotating interfaces, the contra-rotating interface corresponds to two of vaneless contra-rotating rotors. A rotating direction of an upstream rotor of the two vaneless contra-rotating rotors and a rotating direction of a downstream rotor of the two vaneless contra-rotating rotors are opposite. Rectifier stator vanes are not provided among all the rotors to supply sufficient inlet negative pre-swirl for the downstream rotors through the upstream rotors. Only the outlet guide vanes of the last stage, of the vaneless contra-rotating rotors are provided. The number of stages and the number of vaneless contra-rotating interfaces may be set flexibly according to the actual pressurization requirements.

A gas turbine engine that has improved fuel burn provides operability and/or maintenance requirements when installed on an aircraft. The gas turbine engine is provided with a core compressor that includes twelve, thirteen or fourteen rotor stages. The gas turbine engine has a ratio of a core compressor aspect ratio divided by a core compressor pressure ratio is in the range of from 0.03 to 0.09. This results in an optimum balance between installation benefits, operability, maintenance requirements and engine efficiency when the gas turbine engine is installed on an aircraft.

A gas turbine engine that has improved fuel burn provides operability and/or maintenance requirements when installed on an aircraft. The gas turbine engine is provided with a core compressor that includes twelve, thirteen or fourteen rotor stages. The gas turbine engine has a ratio of a core compressor aspect ratio divided by a core compressor pressure ratio is in the range of from 0.03 to 0.09. This results in an optimum balance between installation benefits, operability, maintenance requirements and engine efficiency when the gas turbine engine is installed on an aircraft.

A two stage axial fan includes a tubular fan housing, first and second motors which are positioned in series in the fan housing, a first impeller which is positioned in the fan housing and is driven by the first motor, and a second impeller which is positioned in the fan housing and is driven by the second motor. The first motor is positioned on a first foot-mounted motor support structure which is connected to the fan housing and the second motor is positioned on a second foot-mounted motor support structure which is connected to the fan housing.

Disclosed is a fan. The fan includes a support, a first motor, a first blade, a second motor, a second blade and an electronic control board. The first motor and the second motor are both installed on the support. The first motor is coaxial with the second motor. The first motor has a first rotation shaft and the second motor has a second rotation shaft. The first blade is installed on the first rotation shaft. The second blade is installed on the second rotation shaft. A torsion direction of the first blade is opposite to a torsion direction of the second blade. The electric control board is electrically connected to the first motor and the second motor, and includes a speed ratio adjustment device. The fan can provide a variety of air outlet modes and can quickly adjust between different air outlet modes.