Three-stream gas turbine engine with embedded electric machine

A three-stream gas turbine engine, comprising:

• a shaft;
• a primary fan operatively coupled with the shaft;
• a mid-fan positioned downstream of the primary fan and operatively coupled with the shaft, the mid-fan having mid-fan blades;
• a compressor operatively coupled with the shaft downstream of the mid-fan;
• a turbine operatively coupled with the shaft downstream of the compressor;
• and
• an electric machine operatively coupled with the shaft, the electric machine having a stator and a rotor, the rotor rotatable with the shaft, and
• wherein, when operated, the three-stream gas turbine engine defines a tip speed ratio as being equal to or greater than 0.2 and less than or equal to 1.0, the tip speed ratio being defined by a tip speed of the rotor of the electric machine to a tip speed of one of the mid-fan blades.

A three-stream gas turbine engine, comprising:

• a shaft;
• a primary fan operatively coupled with the shaft;
• a mid-fan positioned downstream of the primary fan and operatively coupled with the shaft, the mid-fan having mid-fan blades;
• a compressor operatively coupled with the shaft downstream of the mid-fan;
• a turbine operatively coupled with the shaft downstream of the compressor;
• and
• an electric machine operatively coupled with the shaft, the electric machine having a rotor rotatable with the shaft, and
• wherein the three-stream gas turbine engine defines a mid-fan radius to electric machine radius ratio as being equal to or greater than 1.33 and less than or equal to 3.8, the mid-fan radius to electric machine radius ratio being defined by a radius spanning between a longitudinal axis defined by the three-stream gas turbine engine and a leading edge tip of one of the mid-fan blades of the mid-fan to a radius spanning between the longitudinal axis and an outermost point of the rotor of the electric machine.

A three-stream gas turbine engine, comprising:

• a low pressure shaft;
• a high pressure shaft;
• a primary fan operatively coupled with the low pressure shaft, the primary fan having primary fan blades;
• a mid-fan positioned downstream of the primary fan and operatively coupled with the low pressure shaft, the mid-fan having mid-fan blades;
• and
• an electric machine operatively coupled with the low pressure shaft or the high pressure shaft, and
• wherein the three-stream gas turbine engine defines a primary fan radius to mid-fan radius ratio as being equal to or greater than 3.0 and less than or equal to 6.5, the primary fan radius to mid-fan radius ratio being defined by a radius spanning between a longitudinal axis defined by the three-stream gas turbine engine and a leading edge tip of one of the primary fan blades of the primary fan to a radius spanning between the longitudinal axis and a leading edge tip of one of the mid-fan blades of the mid-fan, and
• wherein the three-stream gas turbine engine and the electric machine define a mid-fan radius to electric machine radius ratio as being equal to or greater than 1.33 and less than or equal to 3.8, the mid-fan radius to electric machine radius ratio being defined by a radius spanning between the longitudinal axis and a leading edge tip of one of the mid-fan blades of the mid-fan to a radius spanning between the longitudinal axis and an outermost point of a rotor of the electric machine.