| 摘要 |
A changeover valve for a tandem fan type of engine is located in a duct between fan stages at either end. The valve arrangement has a butterfly flap valve to selectively obstruct flow along the cut, a drop-down chute to eject front fan flow and secondary inlet means to induct air to the second fan stage to supply the core engine. The secondary inlet means comprises drop-in doors hinged to pivot into the duct behind the flap valve. A tertiary airflow in a space defined by the duct and an engine nacelle is admitted to the region at the second fan entry face which is shadowed by the secondary inlet doors.
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