| 摘要 |
1499882 Silencing gas turbine engines ROLLS-ROYCE Ltd 9 Feb 1976 [14 Feb 1975] 6316/75 Headings F1G and F1J [Also in Division F2] A sound attenuating structure 10 comprises a metal sheet 12 which has a large number of small holes 14 in it, a cellular metal structure 16 in the form of a honeycomb layer, and a further metal sheet 18 which has a number of flanged holes 20 in it, sheets 12 and 18 being fixed to respective sides of honeycomb layer 16 e.g. by brazing. A further sheet 22 is formed into a flanged box and welded via its flange 24 to the periphery of the structure, the space between the sheet 22 and the perforate sheet 18 being filled with a bulk absorber material 26, e.g. a ceramic fibrous material. Each cell wall of the honeycomb layer 16 is provided with slots 28 below the lips of respective flanges 20a of the holes 20 in sheet 18. In Fig. 3, a gas turbine engine air intake 30 is shown as including a portion made up from such a sound attenuating structure 10 of which the porous sheet 12 forms the surface exposed to intake air-flow and noise emitted from the engine. Rainwater or condensation, if present, will enter the small holes 14 but will be reduced to small globules which, due to surface tension, will cling to the undersurface of sheet 12 and run down the cell walls to collect in channels 32 formed by the flanges 20a, from whence it can pass from cell to cell via slots 28 and to atmosphere via a suction pump 34 and appropriate ducting 36. Where the structure 10 is utilized to form part of the inner wall of a jet pipe (not shown) and is thus exposed to fuel spillage, the spilled fuel is collected as above and drained overboard, or returned through a suitable filter system to the fuel tube. |
