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.

An HVAC system includes a variable-speed compressor which compresses refrigerant flowing through the HVAC system, a blower which provides a flow of air through the HVAC system at a controllable flow rate, and a controller communicatively coupled to the variable-speed compressor and the blower. The controller receives a demand request, which includes a command to operate the HVAC system at a predefined setpoint temperature. In response to receiving the demand request, a setpoint temperature associated with the HVAC system can be adjusted to the predefined setpoint temperature. A speed of the variable-speed compressor is decreased to a low-speed setting. Based on the decreased speed of the variable-speed compressor, an air-flow rate can be determined to provide by the blower. The controllable flow rate of the flow of air provided by the blower can be adjusted based on the determined air-flow rate.

A vertical-cavity surface-emitting laser device including a lower mirror, an upper mirror disposed over the lower mirror, an active region disposed between the lower mirror and the upper mirror, a lower n-type cladding layer disposed between the active region and the lower mirror, an upper n-type cladding layer disposed between the active region and the upper mirror, a heavily doped p-type semiconductor layer disposed between the active region and the upper n-type cladding layer, and a heavily doped n-type semiconductor layer disposed between the heavily doped p-type semiconductor layer and the upper n-type cladding layer to form a tunnel junction with the heavily doped p-type semiconductor layer.

There is described a method of operating a gas turbine engine having a rotor rotatable about a rotation axis, a core gas path defined annularly around the rotation axis, and a casing defining a wall to the core gas path. The method generally has: generating compressed air from a compressed air source, the compressed air source being external relative the gas turbine engine; and guiding the compressed air in sequence from the compressed air source, radially inwardly relative the rotation axis, through a bleed port and into the core gas path.

A method for controlling a turbomachine including a temporary power-increasing device, the control method including a step wherein the flow rate of the coolant injected is adjusted as a function of the atmospheric pressure and/or of the ambient temperature and/or of at least one parameter such as the speed of rotation of a gas generator, the speed of rotation of a low-pressure turbine or of a power turbine, the gas pressure at the outlet of a compressor stage, the temperature at the inlet of the low-pressure turbine or of the power turbine, the engine torque, and/or the collective pitch of a helicopter rotor or the pitch of a propeller of a turboprop.

A thermal energy system for use with an aircraft includes a cooling loop and a cooler. The cooling loop includes a fluid conduit and a pump configured to move fluid through the fluid conduit to transfer heat from a heat source to the fluid in the fluid conduit to cool the heat source. The cooler includes an air-stream heat exchanger located in a duct and is in thermal communication with the fluid conduit to transfer heat between the fluid in the cooling loop and the air passing through the duct.

A thermal energy system for use with an aircraft includes a cooling loop and a cooler. The cooling loop includes a fluid conduit and a pump configured to move fluid through the fluid conduit to transfer heat from a heat source to the fluid in the fluid conduit to cool the heat source. The cooler includes an air-stream heat exchanger located in a duct and is in thermal communication with the fluid conduit to transfer heat between the fluid in the cooling loop and the air passing through the duct.

A compressor case to blade tip clearance system comprising a rotor having blades with tips, the case including an inner case comprising at least one surface feature fluidly coupled to a distribution manifold disposed in a cooling air passageway, the at least one surface feature configured to interact with the cooling air, and a tip clearance located between the tips and the inner case; wherein the tip clearance is maintained responsive to a flow of the cooling air over the at least one surface feature.

An air supply system for a gas turbine engine including a first duct which is connected or capable of being connected to a first compressor bleed air supply of a gas turbine engine; a second duct which downstream of the first compressor bleed air supply is connected or capable of being connected to a second compressor bleed air supply of the gas turbine engine; a nozzle by way of which air from the second duct is capable of being blown into the first duct; and an exhaust air duct having an opening which downstream of the nozzle is disposed in the first duct in such a manner that air blown by way of the nozzle into the first duct can flow out of the first duct through the opening into the exhaust air duct. A gas turbine engine and an aircraft are furthermore provided.

A controller includes: a control unit configured to calculate a control command value of an opening degree of a solenoid valve to control an opening degree of the solenoid valve; and an acquisition unit configured to acquire an estimated amount and a target amount of a working fluid in a labyrinth chamber, and a rotation speed of a drive shaft. The control unit calculates a final control command value based on a feedback control command value and a feedforward control command value, and controls the solenoid valve, the feedback control command value being calculated based on deviation between the estimated amount and the target amount, the feedforward control command value being used to maintain a rotation speed of a fan constant based on the estimated amount and the rotation speed of the drive shaft.