Airflow mixer assembly for a gas turbine engine

A gas turbine engine defining a radial direction, an axial direction, and a circumferential direction, the gas turbine engine comprising:

• a turbomachine having a compressor section, a combustion section, a turbine section, and an exhaust in serial flow order, the turbomachine further comprising a core cowl enclosing at least in part the turbine section and the exhaust;
• a fan section comprising a fan drivingly coupled to the turbomachine;
• and
• an airflow mixer assembly comprising:
• a low pressure duct positioned within the core cowl;
• a plenum extending along a circumferential direction located downstream of the low pressure duct and in fluid communication with the low pressure duct;
• a mixer located downstream of the plenum and downstream of the exhaust and in fluid communication with both the plenum and the exhaust for mixing a low pressure airflow from the low pressure duct with an exhaust gas flow from the exhaust;
• an outer shroud extending along the circumferential direction and along the axial direction at a location around the mixer and downstream of the mixer;
• and
• a variable three way valve, and wherein the low pressure duct is in selective fluid communication with a first low pressure airflow source and a second low pressure airflow source via the variable three way valve.

A gas turbine engine defining an axial direction, a radial direction, and a circumferential direction, the gas turbine engine comprising:

• a turbomachine comprising a compressor section, a combustion section, a turbine section, and an exhaust arranged in serial flow order, the turbomachine defining an engine inlet to an inlet duct, a fan duct inlet to a fan duct, and a core inlet to a core duct, the turbomachine further comprising a core cowl enclosing at least in part the turbine section and the exhaust;
• a primary fan driven by the turbomachine;
• a secondary fan located downstream of the primary fan within the inlet duct, the gas turbine engine defining a thrust to power airflow ratio between 3.5 and 100 and a core bypass ratio between 0.1 and 10, wherein the thrust to power airflow ratio is a ratio of an airflow through a bypass passage over the turbomachine plus an airflow through the fan duct to an airflow through the core duct, and wherein the core bypass ratio is a ratio of the airflow through the fan duct to the airflow through the core duct;
• and
• an airflow mixer assembly comprising:
• a low pressure duct positioned within the core cowl;
• a plenum extending along the circumferential direction located downstream of the low pressure duct and in fluid communication with the low pressure duct;
• an inner shroud located downstream of the plenum and downstream of the exhaust and in fluid communication with both the plenum and the exhaust;
• and
• an outer shroud located outward of the plenum along the radial direction and extending along the circumferential direction and along the axial direction over and downstream of the inner shroud.