METHOD AND DEVICE FOR SILENCING JET NOISE OF ENGINES Russian patent published in 1997 - IPC

FIELD: aero-engine manufacture; silencing jet noise of turbojet engines and double-flow jet engines. SUBSTANCE: jet of gas or air is blown around outer edge of jet engine nozzle. In case of change of mode of operation of engine, exhaust velocity of additional jet is regulated to keep it higher than velocity of incoming flow and below exhaust velocity of main jet. Device for realization of this method has outer casing 1 of engine and nozzle 2. Engine nozzle 2 is embraced by head 3 mounted on engine outer casing or by separate chambers with blind front wall forming slotted passage 4 at outlet in exit section of nozzle 2. Head 3 or each separate chamber are brought in communication by means of pipe line 5 provided with adjustable damper 6 and gas receiver 7 embracing engine outer casing 1 and connected with inner chamber of engine by means of holes 8. Control system of damper 6 includes flight speed sensor 9 with transducer 10 and exhaust velocity sensor 11 with transducer 12. Outputs of transducers 10 and 12 are connected with inputs of comparison unit 13; output of comparison unit 13 is connected with input of solver 14 whose output is connected with input of control unit 15 of damper 8. Feedback in form of additional slit flow velocity sensors is introduced in control system for exhaust unit of doubleflow turbojet engine with separate coaxial nozzles. EFFECT: effective suppression of jet noise. 5 cl, 2 dwg