A method is provided during which an aircraft powerplant is provided. The aircraft powerplant includes a combustor and a water recovery system. The water recovery system includes a condenser and a reservoir. Fuel is combusted within the combustor to provide combustion products. Water is extracted from the combustion products using the condenser. The water recovery system is operated in one of a plurality of modes based on likelihood of contrail formation. The modes include a first mode and a second mode, where the water is collected within the reservoir during the first mode, and where the water passes through the water recovery system during the second mode.

A method of modulating a cooling supply in a gas turbine engine includes providing the engine comprising a compressor section and a turbine section and including a cooling flow circuit, the cooling flow circuit supplying a cooling air flow from a compressor cavity in the compressor section to a blade ring cavity in the turbine section, wherein the cooling flow circuit includes a main line with a full capacity valve, measuring a first pressure in the blade ring cavity, measuring a second pressure in the compressor cavity, adjusting, by a control system, the opening of the full capacity valve to control the cooling air flow through the main line in order to maintain a target pressure ratio, wherein the pressure ratio defined as a ratio of the first pressure to the second pressure. The method is performed in an ambient temperature operating range of the engine.

A system and method for predicting a remaining oil life of oil in a gearbox of an air turbine starter of a vehicle. The method includes generating a temperature data, generating an environmental data set by an environmental sensor, predicting a remaining oil life based on the temperature data set and the environmental data set and scheduling a maintenance event in response to the prediction of the remaining oil life.

A method, system and apparatus are provided for reducing or eliminating contrails formed by an aircraft as it travels through the sky, and more particularly, to disrupting formation of contrails and altering the electromagnetic properties of already-formed contrails through use of one or more lasers. Methods include: positioning at least one laser such that at least one beam from the at least one laser is directed to a position at which contrails form aft of a wing of the aircraft; detecting contrail formation in the position at which contrails form aft of the wing of the aircraft; activating the at least one laser source in response to detecting contrail formation; and reducing or eliminating the contrail in response to activating the at least one laser source.

An aircraft including lean-burn gas turbine engines operating in pilot-plus-mains mode with a given initial fuel flow W.sub.0, a method of controlling the optical depth of contrails produced by a first group of engines includes the steps of (i) reducing fuel flow to each engine in the first group to change the operation of each engine from pilot-plus-mains mode to pilot-only mode, and (ii) adjusting fuel flow to one or more engines in a second group of engines such that the total fuel flow to engines of the second group is increased, all engines of the second group remaining in pilot-plus-mains mode, and wherein the set of lean-burn engines consists of the first and second groups. Depending on atmospheric conditions, the average optical depth of contrails produced by the engines may be enhanced or reduced compared to when all engines operate in pilot-plus-mains mode with a fuel flow W.sub.0.

A propulsion system for an aircraft includes a gas turbine engine and a fuel tank, wherein the fuel includes at least a proportion of a sustainable aviation fuel—SAF—having a density between 90% and 98% of the density, ρ.sub.K, of kerosene and a calorific value between 101% and 105% the calorific value CV.sub.K, of kerosene. The engine includes a combustor; and a fuel pump arranged to supply a fuel thereto at an energy flow rate, C, the pump being arranged to output fuel at a volumetric flow rate, Q, the percentage of fuel passing through the pump not provided to the combustor being referred to as a spill percentage. The fuel include X % SAF, where X % is in the range from 5% to 100%, and has a density, ρ.sub.F, and a calorific value CV.sub.F. The propulsion system is arranged so: the fuel-change spill ratio, R.sub.s, of: $R_s=\frac{\mathrm{spill}\mathrm{percentage}\mathrm{at}\mathrm{cruise}\mathrm{using}\mathrm{kerosene}}{\mathrm{spill}\mathrm{percentage}\mathrm{at}\mathrm{cruise}\mathrm{using}\mathrm{the}\mathrm{fuel}\mathrm{with}X\%SAF}$ is equal to: $\frac{Q-\left(C/\left({\mathrm{CV}}_K\times {\rho }_K\right)\right)}{Q-(C/({\mathrm{CV}}_F\times {\rho }_{}}$

A gas turbine includes a compressor configured to compress air; a combustor configured to mix and combust fuel and compressed air compressed by the compressor; a turbine configured to obtain rotational power using combustion gas generated by the combustor; an inlet guide vane disposed at an intake of the compressor to adjust a flow rate of air flowing into the compressor; a bleed line configured to return a part of the compressed air pressurized in the compressor to the intake of the compressor; and an on-off valve disposed in the bleed line. When the output of the gas turbine increases, a preset maximum value limit of the inlet guide vane is corrected based on a valve opening degree command value of the on-off valve and a compressor intake temperature such that the gas turbine achieves a predetermined performance.

A combustion control system and method for a turbulent jet ignition engine is presented. A controller is configured to access a trained feedforward artificial neural network (ANN) configured to model a first spark from a first ignition source and maximum brake torque (MBT) based on measured operating parameters, generate the first spark and MBT using the ANN, generate a second spark from a second ignition device, and determine a target spark timing. The ANN can be further configured to receive an input related to spark stagger.

Systems and methods for controlling an auxiliary power unit (APU) are provided. The systems and methods may comprise detecting an operating condition of the APU, determining an optimal APU frequency in response to the operating condition, and setting an angular velocity of the APU to the optimal APU frequency.

An aspect includes a system for a gas turbine engine. The system includes one or more bleeds of the gas turbine engine and a control system configured to check one or more activation conditions of a dirt rejection mode in the gas turbine engine. A bleed control schedule of the gas turbine engine is adjusted to extend a time to hold the one or more bleeds of the gas turbine engine partially open at a power setting above a threshold based on the one or more activation conditions. One or more deactivation conditions of the dirt rejection mode in the gas turbine engine are checked. The dirt rejection mode is deactivated to fully close the one or more bleeds based on the one or more deactivation conditions.