| 摘要 |
1,212,593. Jet propulsion plant; turbines. BRITISH AIRCRAFT CORP. Ltd. Jan. 14, 1969 [Jan. 25, 1968], No.3954/68. Headings F1J and F1T. [Also in Division F2] A seal between two coaxial parts, one being stationary and the other rotatable (e.g. a seal for preventing the escape of gas through a gap 15 in a gas turbine jet propulsion engine) comprises an inwardly-facing channel 6 on the stationary part, a flange 13 on the rotatable part extending normal to the axis of rotation and into the channel, a container 7 including a heater 12 for supplying the metal gallium 14 in a liquid state to the channel at a point 9 closer to the rotational axis than the outer diameter of the flange, and means 10 for applying pressure to the container upon rotation of the parts so that upon rotation some of the liquid is expelled into the channel and on stopping the rotation the expelled liquid is returned into the container. The gap 15 is between the combustion chambers 5 and a rotary shroud 2a carrying ducted fan blades 1. Before the engine is started the heater 12 is used to melt the metal. The engine is then rotated and-pressure is transmitted to the container 7 via the duct 10 to transfer the liquid metal 14 by way of a duct 8 into the channel 6 where it is centrifuged to take up the position shown in Fig. 2. As the engine speed increases the gas pressure at the gap 15 displaces the level of the metal in one of the legs of the channel as shown in Fig. 1A such that the centrifugal force exerted by the displaced metal balances the pressure exerted by the gas. Following engine shut down, the metal returns to the container 7 via mouth 9 and duct 8 to solidify. Blades 13a, 13b or scollops may be provided on the flanks of the flange 13 and retaining lips 6a, 6b may be provided on the channel. The forces acting axially on the flange 13 due to unequal levels in the channel during operation are opposed to the thrust of the fan blades 1. |
