A bleed air control system is configured to vary the air pressure at the inlet of a gas turbine engine. The bleed air control system includes a first gas turbine engine configured to provide bleed air, a second gas turbine engine acting as an auxiliary power unit, and a bleed air control system configured to selectively provide bleed air from the first gas turbine engine to the second gas turbine engine.

A turbine engine including a fan, a nacelle circumscribing at least the fan, a compressor section downstream of the fan, and a conduit defined, at least in part, by the nacelle. The conduit includes a first opening at the compressor section, a second opening downstream of the fan and upstream of the compressor section, and a third opening upstream of the fan. Pressure sensors coupled to the nacelle are communicatively coupled to at least one actuator. The at least one actuator can adjust airflow between the first opening and the second opening, or between the first opening and the third opening. The pressure sensors can provide outputs for generating commands that control the at least one actuator.

A method of determining an inlet total air pressure includes determining a first parameter indicative of a first inlet total air pressure. The method includes executing a sequence that includes: determining a mass air flow passing through the air inlet based on the first parameter, determining a Mach number of air passing through the air inlet based on the mass air flow, determining a static air pressure at the air inlet, determining an air pressure ratio based on the Mach number, generating a subsequent parameter indicative of the revised inlet total air pressure based on the air pressure ratio and the static air pressure, and substituting the subsequent parameter for the first parameter. The method includes executing at least one additional instance of the sequence with the subsequent parameter, and outputting the subsequent parameter as the inlet total air pressure.

Repeated cycles each consist of a pump down phase and a holding phase, wherein a start timepoint of each cycle is the timepoint when a rise in an inlet pressure of the pump is sufficiently large and the time extending between two consecutive cycle start timepoints is a cycle time. A control method includes determining a start of a next cycle during a present cycle, wherein it is preferable that the present cycle directly precedes the next cycle. The method further includes controlling the pump to accelerate to a maximum allowed speed during the holding phase of the present cycle before the start of the next cycle such that at the start of the next cycle full pump capacity is available.

A method for detecting a rotating stall includes: determining a level of variation of a static pressure in a combustion chamber of the turbojet engine around an average value of this static pressure; comparing the level of variation of the static pressure relative to a first threshold; comparing a temperature measured at the outlet of a turbine of the turbojet engine relative to a second threshold; and if the level of variation of the static pressure is greater than the first threshold and the temperature at the outlet of the turbine is greater than the second threshold, detecting a presence of a rotating stall.

Systems and methods for adjusting airflow distortion in a gas turbine engine using a secondary airflow passage assembly are disclosed. A gas turbine engine can include a compressor section, a combustion section, and a turbine section in series flow and defining at least in part an engine airflow path. A casing can enclose the gas turbine engine and be at least partially exposed to a bypass airflow. The gas turbine engine can further include a secondary airflow passage assembly comprising a door and a duct, the duct defining an inlet located on the casing, the duct defining an outlet in airflow communication with the engine airflow path, the duct comprising an airflow passage extending between the inlet and outlet. The door can be moveable between an open and closed position to allow a portion of the bypass airflow to flow through the airflow passage to adjust airflow distortion.

In an embodiment, a system includes a gas turbine controller. The gas turbine controller is configured to receive a plurality of sensor signals from a fuel composition sensor, a pressure sensor, a temperature sensor, a flow sensor, or a combination thereof, included in a gas turbine engine system. The controller is further configured to execute a gas turbine model by applying the plurality of sensor signals as input to derive a plurality of estimated gas turbine engine parameters. The controller is also configured to execute a flame holding model by applying the plurality of sensor signals and the plurality of estimated gas turbine engine parameters as input to derive a steam flow to fuel flow ratio that minimizes or eliminates flame holding in a fuel nozzle of the gas turbine engine system.

An apparatus and method of controlling a multi-stage compressor of a gas turbine engine having a front-block of stages with variable stator vanes (VSVs), a rear block of stages downstream of the front-block, and a bleed air off-take from at least one of the stages. The method includes sensing the pressure of the bleed air from the bleed air off-take and adjusting the position of the VSV for the front-block.

A fan is described, with the aid of which a volume flow and/or a mass flow of a medium moved by the fan (1) can be determined. This fan comprises an electric motor (2) and an impeller (3) driven by the electric motor (2), wherein the impeller (3) moves a gaseous medium in a media flow from an inflow side (5) to an outflow side (7). The fan additionally comprises a pressure sensor system, a speed ascertainment system, and an evaluation unit. The pressure sensor system is designed to ascertain an actual pressure difference (Δp*) between a first region (10) and a second region (13), wherein the first region (10) and/or the second region (13) is/are formed in the electric motor (2), wherein a pressure (p.sub.A) prevails in the first region (10), which corresponds to a pressure (p.sub.1) present on the inflow side, wherein a pressure (p.sub.B) prevails in the second region (13), which corresponds to a pressure (p.sub.2) present on the outflow side. The speed ascertainment system is designed to ascertain an actual speed (n) of the impeller (3). The evaluation unit is finally designed to quantitatively determine a mass flow and/or a volume flow of the medium based on the actual pressure difference (Δp*), the actual speed (n), and a pressure characteristic curve of the fan (1).

Furthermore, an electric motor for this fan and a corresponding method are disclosed.

An estimation device for estimating a process gas condition in a system for pumping gas from a vacuum chamber into which the gas is injected to perform a treatment process by a vacuum pump attached to the vacuum chamber through a vacuum valve, comprises: a computer having a processor and a memory, wherein the computer estimates a first process gas condition including an injected gas type and a gas flow rate based on correlation data between a valve body opening degree of the vacuum valve and an effective exhaust speed of the system regarding a predetermined gas type and a chamber pressure of the vacuum chamber.