A convertible ducted fan engine having a shroud, a drive shaft connected to a mechanical fan, and a rotational drive motor configured to rotate the mechanical fan. An embodiment includes a linear drive motor configured to translate the drive shaft and mechanical fan in a direction parallel to a longitudinal axis of the shroud. The convertible ducted fan engine includes a fluid-propulsion configuration in which the mechanical fan rotates freely with respect to the shroud to produce thrust through fluid flow, and a drive-wheel configuration in which the shroud rotates about the rotational axis.

A cold plate assembly for cooling an electronic device includes a manifold, a comb insert, and a first vaned plate. The manifold is formed to define a cavity therein. The comb insert is located in the cavity includes channels defined by walls for receiving a fluid from passages in the manifold and transferring heat to the fluid. The first vaned plate includes a first panel and first channel vanes extending away from the first panel. The first vaned plate is removably coupled with the comb insert such that first channel vanes are located within the channels to guide the fluid. Each first channel vane extends from a wall toward a neighboring wall at an angle to direct the fluid to impinge upon the neighboring wall with increased velocity so as to increase the heat transfer between the neighboring wall and the fluid.

A gas turbine engine according to an exemplary embodiment of this disclosure includes among other possible things, a fan section including a plurality of fan blades, a first electric motor assembly that provides a first drive input for driving the fan blades about an axis, a turbine section, and a geared architecture driven by the turbine section and coupled to the fan section to provide a second drive input for driving the fan blades, and second electric motor assembly is coupled to rotate the geared architecture relative to a fixed structure controls a speed of the fan blades provided by a combination of the first drive input and the second drive input.

A mobile fracking system and methods may include a gas turbine housed at least partially inside a trailer and an exhaust attenuation system configured to receive exhaust gas from the gas turbine. The exhaust attenuation system may include a lower elongated plenum configured to receive exhaust gas from the gas turbine and an upper noise attenuation system that is movably connected relative to a distal end of the lower elongated plenum.

A twin-engine system includes a gas turbine engine comprising a core and a first output shaft drivable by the core. An electric engine has an electric motor configured to drive a second output shaft. A reduction gear box (RGB) has an RGB input drivingly engaged to both the first output shaft and the second output shaft. The RGB has an RGB output to provide rotational output to a rotatable load.

A reverse-flow gas turbine engine includes a core of the gas turbine engine comprising multiple spools rotatable about a center axis of the gas turbine engine. Each spool is configured to pressurize air and to extract energy from combustion gases. The air and combustion gases are configured to flow through the core in a forward direction from an air inlet at an aft end of the core to an outlet at a forward end of the core. A propeller is disposed forward of the outlet. A reduction gearbox (RGB) is drivingly engaged to the core. An electric motor is drivingly engaged to the propeller and disposed axially between the RGB and the propeller.

A gas turbine engine according to an exemplary embodiment of this disclosure includes among other possible things, a fan section including a plurality of fan blades, a first electric motor assembly that provides a first drive input for driving the fan blades about an axis, a turbine section, and a geared architecture driven by the turbine section and coupled to the fan section to provide a second drive input for driving the fan blades, and second electric motor assembly is coupled to rotate the geared architecture relative to a fixed structure controls a speed of the fan blades provided by a combination of the first drive input and the second drive input.

A combined cycle power generation system for an aircraft includes fuel cell and supercritical CO.sub.2 cycles. The fuel cell cycle includes a compressor and turbine disposed on a first shaft, a fuel cell in fluid communication with the compressor and a fuel source, and a combustor in fluid communication with the fuel cell and the turbine. The combustor is configured to combust partially spent fuel from the fuel cell and produce combustion exhaust gas for delivery to the turbine. The supercritical CO.sub.2 cycle includes a compressor and turbine disposed on a second shaft, a supercritical CO.sub.2 fluid circuit in thermal communication with the combustor and configured to deliver CO.sub.2 to the turbine and compressor, and a heat exchanger in thermal communication with the supercritical CO.sub.2 fluid circuit and a source of cooling fluid. A mechanical linkage is configured to transfer power from the second shaft to the first shaft.

A method for operating a hybrid electric propulsion system of an aircraft, the hybrid electric propulsion system comprising a turbomachine, an electric machine coupled to the turbomachine, and a propulsor coupled to the turbomachine, the method comprising: operating the turbomachine to drive the propulsor; receiving data indicative of a failure condition of the hybrid electric propulsion system; and extracting power from the turbomachine using the electric machine to slow down one or more rotating components of the turbomachine in response to receiving the data indicative of the failure condition.

Techniques for determining a fan spool speed value associated with a hybrid electric gas engine (“engine”) are described herein. For example, a method includes generating a first fan spool speed value based on a base extraction amount. The method further includes generating a change in the first fan spool speed value based on a flight condition and a change in extraction amount. The method further includes generating a second fan spool speed value based on the extraction amount and an augmentation value for intersection of a combustion instability and burner pressure limit. The method further includes generating a second change in the second fan spool speed value based on the flight condition and the change in extraction amount. The method further includes determining a final fan spool speed value and operating the engine at the final fan spool speed value.