A method for reducing an engine core speed is disclosed, which includes determining a condition of an engine during operation of the engine, and controlling an engine turbine clearance based on the condition of the engine so as to influence the engine core speed. An engine system comprising an engine core speed reducing system is also disclosed.

Example apparatus, systems, and articles of manufacture to control deflection mismatch are disclosed herein. Further examples and combinations thereof include: A deflection limiter comprising an inner shroud segment to support a stator structure, the inner shroud segment including a first end face and a first outer upper portion, the first end face positioned radially inward and aft relative to the first outer upper portion, and an outer shroud segment to support the inner shroud segment, the outer shroud segment including a second end face and a second outer upper portion, the second end face positioned aft relative to the first end face and the second outer upper portion positioned aft relative to the first outer upper portion of the inner shroud segment, the second end face coupled to the first end face of the inner shroud segment and the second outer upper portion coupled to the first outer upper portion.

Systems and methods for measuring the clearance gaps between rotating and stationary components of a turbomachine are provided. In one exemplary aspect, flexible and degradable sensing arrays that include a plurality of microwave sensors are utilized to sense the clearance gaps between rotating and stationary components of the turbomachine. Microwaves generated by a microwave generator are transmitted to the sensors. Upon rotation of the rotating components, the rotating components reflect the microwaves transmitted thereto. The microwave sensors capture the transmitted signal and also capture a reflected signal indicative of the transmitted signal reflected by the rotating components. The signals are then forwarded to a computing device for processing. The amplitude difference at the interference fringes between the superimposed signals is representative of the clearance gaps between the rotating and stationary components. After measuring the clearance gaps, the turbomachine may be operated and the degradable sensing array may be consumed.

A blade tip sensor may be provided that includes a bridge-network circuit embedded in a composite body such as a ceramic matrix composite body. The bridge-network circuit may include a first resistor-capacitor circuit on a first branch and a second resistor-capacitor circuit on a second branch. Each of the first resistor-capacitor circuit and the second resistor-capacitor circuit includes a corresponding capacitor having a capacitance that depends on a distance between the corresponding capacitor and a blade of a rotor.

A patch antenna array sensor is provided. The patch antenna array sensor includes a ceramic matrix composite body in which a patch antenna array is embedded, wherein the patch antenna array sensor is configured to detect blade tip clearance or some other aspect of one or more blades in a gas turbine engine.

A patch antenna array sensor is provided. The patch antenna array sensor includes a ceramic matrix composite body in which a patch antenna array is embedded, wherein the patch antenna array sensor is configured to detect blade tip clearance or some other aspect of one or more blades in a gas turbine engine.

A gas turbine engine for an aircraft includes an engine core including a first, lower pressure, turbine, a first compressor, and a first core shaft connecting the first turbine to the first compressor; and a second, higher pressure, turbine, a second compressor, and a second core shaft connecting the second turbine to the second compressor, and a fan located upstream of the engine core and including a plurality of fan blades extending from a hub. A low pressure turbine temperature change is defined as: $\frac{\mathrm{the}\mathrm{first}\mathrm{turbine}\mathrm{entrance}\mathrm{temperature}}{\mathrm{the}\mathrm{first}\mathrm{turbine}\mathrm{exit}\mathrm{temperature}}.$
A fan tip temperature rise is defined as: