GB824503A - Jet engine exhaust silencer - Google Patents

Abstract

824,503. Silencing exhaust. UNITED AIRCRAFT CORPORATION. April 24, 1957 [April 30, 1956], No. 13039/57. Class 7(2) Aircraft jet engines are silenced on the ground by discharging them through a plurality of small holes 48<SP>1</SP>, Fig. 2, the spacing of which is such that the resulting small jets remain separate for a substantial distance from the holes, such spacing being preferably at least three times the hole diameter. The number and size of the holes 48' is preferably such that the flow characteristics therethrough approximate those through the unblocked engine jet nozzle 28<SP>1</SP>, to effect which a pilot-controlled radially or circumferentially adjustable perforated sleeve 52 may be provided. The cylindrical member 30<SP>1</SP> in which the holes 48<SP>1</SP> are formed may be of greater diameter than the nozzle 28', an initial smoothing duct 32<SP>1</SP> being enlarged suddenly or via a diffuser. A shown, the silencer is supported on the engine by its connecting clamp ring 40, but it may be mounted on a trolley and have a flexible connection in the duct 32<SP>1</SP>, or may be completely ground supported and unattached to the engine. The member 30<SP>1</SP> may have a rearwardly-open cylindrical shield or a series of frusto-conical shields 69, Fig. 10A, reacting against abutments 73 and of twopart construction. Fig. 6 shows a telescopic diffuser 72 and an upwardly directed silencer outlet having a shield 86 and which may be replaced by an upwardly directed diffuser having a slightly rounded end closure containing the holes 48'.