Noise reduction system for gas turbine engine for aircraft has surface cladding for hot gas channel downstream of turbine, with circular perforated plates covering large ends of frustoconical spaces

摘要

The frustoconical spaces (H) have perforated conical sides and flat bottoms (HH) and project into rectangular spaces (HR) with straight sidewalls (SF). Each space has a flat floor (GF) and a gently curved outer surface (AB) in contact with the hot gas stream. Circular plates or areas (P) have perforations and cover the wide ends (HM) of the frustoconical spaces. The sound absorption system acts as Helmholz resonators with gas at a temperature of 440 degrees C flowing at Mach 0.3. The depth of the recesses is 34 mm. The length of the frustoconical spaces is 23 mm. The diameter of the wide ends is 34 mm and the diameter of the narrow ends is 7 mm. the perforations may be 1 mm in diameter and cover 20% of the area of the plates.