Various embodiments include a system having: at least one computing device configured to tune a set of gas turbines (GTs) by performing actions including: commanding each GT in the set of GTs to a base load level, based upon a measured ambient condition for each GT; commanding each GT in the set of GTs to adjust a respective output to match a nominal mega-watt power output value, and subsequently measuring an actual fuel flow value and an actual emissions value for each GT; adjusting at least one of a fuel flow or a water flow for each GT to an adjusted water/fuel ratio in response to the actual emissions value deviating from an emissions level associated with the base load level, while maintaining the respective adjusted output; and adjusting an operating condition of each GT in the set of GTs based upon a difference between the respective measured actual fuel flow value and a nominal fuel flow value at the ambient condition, while maintaining the adjusted water/fuel ratio.

A valve assembly includes an outer housing having a first opening in fluid communication with a first fluid, a second opening in fluid communication with a second fluid, a third opening in fluid communication with a third fluid and a fourth opening in fluid communication with a fourth fluid. The valve assembly includes a piston configured to slide within the outer housing into a first position at which the third opening is blocked from fluid communication with the fourth opening based on a fluid pressure of the first fluid being greater than a fluid pressure of the fourth fluid. The piston is further configured to slide within the outer housing into a second position at which the third opening is in fluid communication with the fourth opening based on the fluid pressure of the second fluid being greater than the fluid pressure of the fourth fluid.

A valve assembly includes an outer housing having a first opening in fluid communication with a first fluid, a second opening in fluid communication with a second fluid, a third opening in fluid communication with a third fluid and a fourth opening in fluid communication with a fourth fluid. The valve assembly includes a piston configured to slide within the outer housing into a first position at which the third opening is blocked from fluid communication with the fourth opening based on a fluid pressure of the first fluid being greater than a fluid pressure of the fourth fluid. The piston is further configured to slide within the outer housing into a second position at which the third opening is in fluid communication with the fourth opening based on the fluid pressure of the second fluid being greater than the fluid pressure of the fourth fluid.

A method is provided of controlling a gas turbine having a shaft connecting a compressor to a turbine, as well as having a reheat system, and a gas turbine. The method includes the steps of: operating the engine using the reheat system to provide a mass flow rate of reheat fuel into a gas flow of the gas turbine engine downstream of an exit of the turbine; detecting a shaft break event in the shaft; and in response to this detection, maintaining the mass flow rate of the reheat fuel being provided into the gas flow downstream of the turbine exit, whereby the maintained mass flow rate of reheat fuel raises a back pressure downstream of the turbine and thereby reduces a rotational speed of the turbine.

A multi-spool turbomachine having an electric machine that can be controlled to input power to one of the spools of the turbomachine is provided. In one aspect, the multi-spool turbomachine can be a hybrid electric gas turbine engine for an aircraft. The hybrid electric gas turbine engine can include a first spool, a second spool, and an electric machine operatively coupled with the first spool. In response to an increase in thrust demand, the electric motor receives electrical power from an electrical power source. In turn, the electric machine applies a torque to the first spool, causing the first spool to increase in rotational speed. In this manner, the electric machine can electrically assist the turbomachine to meet the increase in thrust demand.

A method of calibrating a gas turbine engine having a propulsive fan, and an engine core, the method including: measuring a total thrust generated by the engine; measuring the thrust generated by the engine core; measuring first and second engine performance parameters; based on the total thrust and engine core thrust, determining a thrust generated by the propulsive fan; providing a first power setting parameter associating the fan thrust with the first engine performance parameter; and providing a second power setting parameter associating the engine core thrust with the second engine performance parameter.

A method of calibrating a gas turbine engine having a propulsive fan, and an engine core, the method including: measuring a total thrust generated by the engine; measuring the thrust generated by the engine core; measuring first and second engine performance parameters; based on the total thrust and engine core thrust, determining a thrust generated by the propulsive fan; providing a first power setting parameter associating the fan thrust with the first engine performance parameter; and providing a second power setting parameter associating the engine core thrust with the second engine performance parameter.

Various embodiments include a system having: at least one computing device configured to tune a set of gas turbines (GTs) by performing actions including: commanding each GT in the set of GTs to a base load level, based upon a measured ambient condition for each GT; commanding each GT in the set of GTs to adjust a respective output to match a nominal mega-watt power output value, and subsequently measuring an actual fuel flow value for each GT; adjusting an operating condition of each GT in the set of GTs based upon a difference between the respective measured actual fuel flow value and a nominal fuel flow value at the ambient condition; commanding each GT in the set of GTs to a part load level, the part load level representing a fraction of the base load level, and subsequently measuring an actual fuel flow value for each GT at the part load level; and calibrating the set of GTs based upon a difference between the measured actual fuel flow value at the part load level and the measured actual fuel flow value after adjusting the output to match the nominal mega-watt power output value.

Various embodiments include a system having: at least one computing device configured to tune a set of gas turbines (GTs) by performing actions including: commanding each GT in the set of GTs to a base load level, based upon a measured ambient condition for each GT; commanding each GT in the set of GTs to adjust a respective output to match a nominal mega-watt power output value, and subsequently measuring an actual fuel flow value for each GT; adjusting an operating condition of each GT in the set of GTs based upon a difference between the respective measured actual fuel flow value and a nominal fuel flow value at the ambient condition; commanding each GT in the set of GTs to a part load level, the part load level representing a fraction of the base load level, and subsequently measuring an actual fuel flow value for each GT at the part load level; and calibrating the set of GTs based upon a difference between the measured actual fuel flow value at the part load level and the measured actual fuel flow value after adjusting the output to match the nominal mega-watt power output value.

A method includes combusting a fuel and an oxidant in a combustor of an exhaust gas recirculation (EGR) gas turbine system that produces electrical power and provides a portion of the electrical power to an electrical grid. The method further includes controlling, via one or more processors, one or more parameters of the EGR gas turbine system to decrease the portion of the electrical power provided to the electrical grid in response to an over-frequency event associated with the electrical grid, wherein controlling the one or more parameters comprises decreasing a flow rate of fuel to the combustor in response to the over-frequency event.