SOUND-ABSORBING DEVICE IN TWO-CIRCUIT TURBOJET ENGINE Russian patent published in 2004 - IPC

FIELD: mechanical engineering; turbojet engines. SUBSTANCE: proposed device for sound-absorbing in two-circuit turbojet engine contains ring duct walls with spaces out of the duct in engine outer circuit channel and sound-absorbing devices arranged in said spaces. Each sound-absorbing device is made in form of row of Helmholtz ring resonance chambers. Sound-absorbing devices in spaces out of the duct and made in form of row of fillers, cross section of each being figure with circuit closed in meridional section of engine, mainly in form of quadrangle. Number of butt joint surfaces between fillers in space out of the duct is less than number of fillers in said space by unity. Each filler is connected one side with perforated duct wall and with corresponding side of adjacent filler. Ratio of areas of linings by sound-absorbing structures in spaces out of the duct of outer duct walls of channel of engine outer circuit to areas of linings by sound-absorbing structures in space out of the duct of inner walls of said channels is where is acoustic parameter of channel of engine outer circuit corresponding to logarithmic scale of 5 dB. EFFECT: improved efficiency of sound-absorbing in two-circuit turbojet engine without loss of thrust, reduced engine noise and brought to minimum pressure losses. 6 cl, 6 dwg