In accordance with at least one aspect of this disclosure, there is provided a fuel system for a gas turbine engine of an aircraft, including a main inlet feed conduit fluidly connected to a primary manifold feed conduit and a secondary manifold feed conduit. A primary manifold fluidly connects the primary manifold feed conduit to a plurality of primary fuel injectors, and a secondary manifold fluidly connects the secondary manifold feed conduit to a plurality of secondary fuel injectors.

Examples described herein provide a computer-implemented method that includes determining a thrust requirement to satisfy a desired glide slope. The method further includes determining, based on the thrust requirement, whether thrust matching can be maintained while operating a first gas turbine engine in a fuel-burning mode and operating a second gas turbine engine in an electrically powered mode. The method further includes, responsive to determining that thrust matching cannot be maintained, commanding fuel flow to a combustor of the second engine to cause the second gas turbine engine to operate in the fuel-burning mode.

The present disclosure relates to systems and methods that are useful in control of one or more aspects of a power production plant. More particularly, the disclosure relates to power production plants, methods of starting power production plants, and methods of generating power with a power production plant wherein one or more control paths are utilized for automated control of at least one action. The present disclosure more particularly relates to power production plants, control systems for power production plants, and methods for startup of a power production plant.

A turbofan gas turbine engine having a bypass duct, and a bypass airflow measurement system. The bypass airflow measurement system comprises: at least one acoustic transmitter configured to transmit an acoustic waveform across the bypass duct of the gas turbine engine though which a bypass airflow passes to at least one acoustic receiver; where the at least one acoustic transmitter and the at least one acoustic receiver are located on an axial plane that is substantially perpendicular to the bypass flow. A method of measuring bypass airflow properties of a turbofan gas turbine engine is also described.

An aircraft has first and second fuel sources containing fuels with different characteristics, and one or more gas turbine engines powered by the fuels and each having a staged combustion system having pilot and main fuel injectors and being operable in pilot-only and pilot-and-main ranges of operation. The gas turbine engines each have a fuel delivery regulator arranged to control fuel delivery to the pilot and main fuel injectors. The method includes: obtaining a proposed mission description; obtaining nvPM impact parameters for the gas turbine engines, the impact parameters being associated with each operating condition of the proposed mission; calculating an optimised set of one or more fuel characteristics for each flight condition of the proposed flight defined in the flight description based on the nvPM impact parameters; and determining a fuel allocation based on the optimised set of one or more fuel characteristics.

A flow metering system includes a pump configured to urge a fluid flow from a fluid source, and a recirculation line located at the pump. A pressure regulating valve is located along the recirculating line. One or more fluid delivery lines extend downstream of the pump to deliver the fluid flow to one or more fluid consumers. A flow control valve is located along each fluid delivery line of the one or more fluid delivery lines. A system controller is operably connected to the pressure regulating valve and the one or more flow control valves. The system controller is configured to maintain a selected delta pressure and a selected flow rate of the fluid flow by operation of the pressure regulating valve and the one or more flow control valves.

Devices, systems and methods for leak detection are provided herein. Also provided are devices, systems and methods for monitoring and/or measuring fluid usage. In some aspects, a system comprising a sensor, a processing system, and a platform are provided. In some aspects, the sensor may be coupled to a spinning device. The sensor can be configured to detect fluid data, which can comprise, for example, displacement data of liquid and/or movement data associated with the liquid in a container and/or flow data associated with a flow of fluid in a conduit. The processing system can be coupled with the sensor and configured to communicate the fluid data. The platform can comprise an application communicatively coupled to one or more databases storing evaluation data (e.g., known pattern data) and configured to receive the fluid data and determine if there is a leak.

Devices, systems and methods for leak detection are provided herein. Also provided are devices, systems and methods for monitoring and/or measuring fluid usage. In some aspects, a system comprising a sensor, a processing system, and a platform are provided. In some aspects, the sensor may be coupled to a spinning device. The sensor can be configured to detect fluid data, which can comprise, for example, displacement data of liquid and/or movement data associated with the liquid in a container and/or flow data associated with a flow of fluid in a conduit. The processing system can be coupled with the sensor and configured to communicate the fluid data. The platform can comprise an application communicatively coupled to one or more databases storing evaluation data (e.g., known pattern data) and configured to receive the fluid data and determine if there is a leak.

Devices, systems and methods for leak detection are provided herein. Also provided are devices, systems and methods for monitoring and/or measuring fluid usage. In some aspects, a system comprising a sensor, a processing system, and a platform are provided. In some aspects, the sensor may be coupled to a spinning device. The sensor can be configured to detect fluid data, which can comprise, for example, displacement data of liquid and/or movement data associated with the liquid in a container and/or flow data associated with a flow of fluid in a conduit. The processing system can be coupled with the sensor and configured to communicate the fluid data. The platform can comprise an application communicatively coupled to one or more databases storing evaluation data (e.g., known pattern data) and configured to receive the fluid data and determine if there is a leak.

A fuel flow measuring system includes an ultrasonic fuel flow sensor. The fuel flow sensor includes a first transducer and a second transducer. The first transducer is excited at multiple different excitation frequencies and a voltage, an electric current, and a phase difference between the voltage and the electric current is sensed at the first transducer during excitation. Data points are generated based on the sensed readings and a model is fit to the data points to determine a complex impedance spectrum. The complex impedance spectrum indicates a range of excitation frequencies within a range of a peak resonance frequency of the first transducer. One or more characteristics of excitation signals directed to the second transducer are set based on the determined complex impedance spectrum. In this manner, the signal to noise ratio of ultrasonic signals emitted by the second transducer and received by the first transducer can be maximized.