Turbine engine tip clearance control utilizing electric machine

An operating method, comprising:

• receiving a command to increase thrust generated by a propulsor rotor from a first thrust level to a second thrust level, the propulsor rotor operatively coupled to an engine core and an electric machine, the engine core including a flowpath, a compressor section, a combustor section and a turbine section, and the flowpath extending through the compressor section, the combustor section and the turbine section from an inlet into the flowpath to an exhaust from the flowpath;
• operating the engine core in a transient state to increase power output from the engine core to the propulsor rotor from a first power level to a second power level in response to the command;
• operating the electric machine to boost the power output from the engine core to the propulsor rotor while the engine core is operating in the transient state;
• and
• operating a clearance control system for the engine core based on the operation of the electric machine;
• wherein the clearance control system is configured to adjust clearance between a first turbine rotor in the turbine section and a first shroud circumscribing the first turbine rotor, based on the operation of the electric machine;
• wherein the engine core is operated in the transient state to maintain a rate of change in temperature of combustion products within the flowpath below a threshold level and reduce differential thermally induced movement between the first turbine rotor and the first shroud during transient operation of the engine core;
• wherein during the operation of the engine core in the transient state and prior to the operation of the electric machine, the clearance control system maintains a first pinch point margin between the first turbine rotor and the first shroud;
• and
• wherein during the operation of the electric machine, the clearance control system changes the first pinch point margin to a second pinch point margin, and the second pinch point margin is less than the first pinch point margin.