By=pass flow turbojet engine rear housing

摘要

The engine's rear housing (1) consists of a primary or inner pipe (2) for ejecting a primary flow of hot gases from the engine's gas generator (5). A secondary or outer pipe (3) is used for ejecting a secondary flow which is basically of dilution air delivered by the engine's fan (4). Both pipes having circular intake ends. The primary pipe has one portion adjacent to its outlet which varies continuously in section from circular at its forward end (6) to elliptical at its rear end (12). The degree of flattening of the ellipse is greater than 1:1 and not more than 3:1, and is preferably between 1:1 and 1.5:1. The pipe is convergent in shape, with its portion of varying section starting immediately after the final stage of a gas generator turbine. In a variant of the design the elliptical end of the primary pipe can have a cross-section varied by adjustable shutters.