Diffuser aspiration for a tip turbine engine
A fan-turbine rotor assembly includes a diffuser section ( 114 ) which turns and diffuses the airflow from a radial core airflow passage ( 80 ) toward an axial airflow direction. Diffuser flow passages communicate with the diffuser passages ( 144 ) at a location which reduces separation of the airflow as the airflow is turned from the radial core airflow passage ( 80 ) toward an axial airflow direction through airflow aspiration at the potentially turbulent locations.
1. A fan blade for a tip turbine engine comprising:
a fan blade section which defines a core airflow passage therethrough, said fan blade section defined about a fan blade axis of rotation;
a diffuser section mounted radially outward from said fan blade section relative said fan blade axis of rotation, said diffuser section defining a diffuser passage and a diffuser flow passage, said diffuser passage in communication with said core airflow passage to turn an airflow from said core airflow passage toward an annular combustor, said diffuser flow passage in communication with said diffuser passage to redirect a portion of said airflow from said diffuser passage; and
a turbine blade which extends radially outward from said diffuser section relative said fan blade axis of rotation, said turbine blade located within a first row of a multi-row turbine to define a turbine blade passage therethrough, said turbine blade passage in communication with said diffuser flow passage to receive said portion of said airflow from said diffuser passage.
2. The fan blade as recited in claim 1 , wherein said diffuser flow passage communicates with said diffuser passage at a location to reduce separation of said airflow through said diffuser airflow passage.
3. The fan blade as recited in claim 1 , wherein said diffuser flow passage turns said airflow to an axial airflow direction.
4. A method of communicating an airflow through a fan blade of a tip turbine engine comprising the steps of:
(1) directing an airflow through a core airflow passage within a fan blade section;
(2) turning the airflow through a diffuser passage in communication with the core airflow passage toward an annular combustor; and
(3) discharging a portion of the airflow from the diffuser passage through a diffuser flow passage to reduce separation of the airflow through the diffuser passage.
5. A method as recited in claim 4 , wherein said step (3) further comprises:
reducing a turbulence of the airflow within the diffuser passage.
6. A method as recited in claim 4 , wherein said step (3) further comprises:
reducing a flow separation of the airflow within the fan blade.
7. A method as recited in claim 4 , wherein said step (2) further comprises:
turning the airflow toward an axial airflow direction.