Methods and systems for supply of fuel for a turbine-driven fracturing pump system used in hydraulic fracturing may be configured to identify when the supply pressure of primary fuel to a plurality of gas turbine engines of a plurality of hydraulic fracturing units falls below a set point, identify a gas turbine engine of the fleet of hydraulic fracturing units operating on primary fuel with highest amount of secondary fuel available, and to selectively transfer the gas turbine engine operating on primary fuel with the highest amount of secondary fuel from primary fuel operation to secondary fuel operation. Some methods and systems may be configured to transfer all gas turbine engines to secondary fuel operation and individually and/or sequentially restore operation to primary fuel operation and/or to manage primary fuel operation and/or secondary fuel operation for portions of the plurality of gas turbine engines.

Methods and systems for supply of fuel for a turbine-driven fracturing pump system used in hydraulic fracturing may be configured to identify when the supply pressure of primary fuel to a plurality of gas turbine engines of a plurality of hydraulic fracturing units falls below a set point, identify a gas turbine engine of the fleet of hydraulic fracturing units operating on primary fuel with highest amount of secondary fuel available, and to selectively transfer the gas turbine engine operating on primary fuel with the highest amount of secondary fuel from primary fuel operation to secondary fuel operation. Some methods and systems may be configured to transfer all gas turbine engines to secondary fuel operation and individually and/or sequentially restore operation to primary fuel operation and/or to manage primary fuel operation and/or secondary fuel operation for portions of the plurality of gas turbine engines.

A gas turbine (A, B, C) is provided that includes at least a compressor (1), a combustor (2), and a turbine (3) and combusts ammonia serving as fuel in the combustor (2), including a reducing agent supply device (6) configured to supply a reducing agent for reducing nitrogen oxides in a combustion gas to at least one of: a combustion gas flow path between the combustor (2) and the turbine (3); and the turbine (3).

A gas turbine (A, B, C) is provided that includes at least a compressor (1), a combustor (2), and a turbine (3) and combusts ammonia serving as fuel in the combustor (2), including a reducing agent supply device (6) configured to supply a reducing agent for reducing nitrogen oxides in a combustion gas to at least one of: a combustion gas flow path between the combustor (2) and the turbine (3); and the turbine (3).

A fuel/air supply device including a fuel supply arrangement designed to convey fuel to a fuel outlet of the fuel/air supply device, a primary air supply arrangement designed to convey air to an air outlet of the fuel/air supply device, and a secondary air supply arrangement connecting the primary air supply arrangement to the fuel supply arrangement at a position upstream of a fuel compressor that is included in the fuel supply arrangement. The secondary air supply arrangement includes an air conduit that has a restricted portion for defining a relatively small air passage in the air conduit, and can be used for realizing a fuel/air mixture of low calorific value if so desired on the basis of a supply of air to the fuel without needing complex control measures.

A fuel/air supply device including a fuel supply arrangement designed to convey fuel to a fuel outlet of the fuel/air supply device, a primary air supply arrangement designed to convey air to an air outlet of the fuel/air supply device, and a secondary air supply arrangement connecting the primary air supply arrangement to the fuel supply arrangement at a position upstream of a fuel compressor that is included in the fuel supply arrangement. The secondary air supply arrangement includes an air conduit that has a restricted portion for defining a relatively small air passage in the air conduit, and can be used for realizing a fuel/air mixture of low calorific value if so desired on the basis of a supply of air to the fuel without needing complex control measures.

A method of controlling a fuel blend for a turbine engine is provided. The method includes supplying a first fuel and a second fuel to a mixer and mixing, in the mixer, the first and second fuels together to obtain a fuel blend. The method also includes receiving, at a fuel blend analyzer downstream from the mixer, a measurement indicative of a composition of the fuel blend. The method further includes combusting the fuel blend in a combustor. The method also includes receiving a combustion signal indicative of combustion behavior. The method further includes controlling, based on at least one of the fuel blend measurement and the combustion signal, by a controller, at least one of a flow of the first fuel and a flow of the second fuel.

Heat exchangers, heat exchanger systems, and hypersonic vehicles are provided. For example, a heat exchanger is provided that comprises a first chamber for receipt of a flow of cool fluid and a second chamber for receipt of a flow of hot fluid. The heat exchanger further comprises a buffer fluid flowpath for circulation of a buffer fluid therethrough. The buffer fluid circulates within the buffer fluid flowpath disposed between the first chamber and the second chamber to transfer heat from the hot fluid to the cool fluid. In certain embodiments, a hypersonic vehicle comprises such a heat exchanger, and the cool fluid is cryogenic or near-cryogenic fuel of the hypersonic vehicle and the hot fluid is engine bleed air from a hypersonic propulsion engine of the vehicle.

An energy extraction system according to an exemplary embodiment of this disclosure, among other possible things includes an ammonia fuel storage tank assembly that is configured to store a liquid ammonia fuel, a thermal transfer assembly that is configured to transform the liquid ammonia fuel into a vaporized ammonia based fuel, a turbo-expander that is configured to expand the vaporized ammonia based fuel to extract work, and an energy conversion device that is configured to use the vaporized ammonia based fuel from the turbo-expander to generate a work output.

In accordance with at least one aspect of this disclosure, a fluid system of an aircraft includes a primary fluid conduit that conveys a primary fluid, and a leak detection system disposed around at least a portion of the primary fluid conduit and forming one or more detection volumes. The leak detection system determines whether there is a primary fluid leak into the one or more detection volumes by sensing a pressure change in the one or more detection volumes.