GB766985A - Improvements in or relating to jet noise suppression means - Google Patents

Abstract

766,985. Silencers for gaseous currents. LILLEY, G. M., WESTLEY, R and YOUNG, A. D. July 21, 1953 [July 25, 1952], No. 18911/52. Class 7 (2). [Also in Group XXVI] Continuously effective means, e.g. tooth-like projections 4, Fig. 1, are provided at or adjacent the exit 3 of a jet nozzle 1 and for modifying the boundary of an issuing jet in such a manner that the mixing region between the jet and the ambient fluid is increased compared with the corresponding region for a plain nozzle exit. As shown in Fig. 1, the projections 4 are distributed around the perimeter of the exit 3 and are bent inwardly toward the axis of the jet. In modifications, (a), Fig. 2 (not shown), alternate projections are parallel to and inclined away from the axis of the jet, (b), Fig. 3 (not shown), the projections are parallel to the axis of the jet, the length of some of the projections being twice that of the remainder, (c), Fig. 4 (not shown), all the projections are in line with the axis of the jet, (d), Fig. 5 (not shown), a shroud is arranged at the downstream tips of the projections to form a number of apertures distributed about the perimeter of the nozzle, (e), Fig. 6 (not shown), three of six projections are in line with the axis of the jet and the remaining projections are inclined inwardly towards that axis at an angle of about 30 degrees, (f), Fig. 7 (not shown), the projections increase in width as they extend away from the exit 3 and are inclined towards the axis of the jet, (g), Fig. 8 (not shown), the projections are fluted at their downstream ends, (h), Fig. 9 (not shown), the projections are of circular arc cross-section at their upstream ends and of right-angled section at their downstream ends, (i), the projections 14, Fig. 10, are radially disposed to impart swirl to the outer regions of the jet and have curved ends 15, (j), Fig. 11 (not shown), the downstream ends of the radial projections 14 shown in Fig. 10 are twisted into planes generally tangential to the jet boundary. In further modifications, (a), there are twelve projections of which alternate projections 17, Fig. 12, are inclined outwardly and the intervening projections 18 are inclined towards the axis of the jet, (b) Fig. 13 (not shown), projections 4 are arranged on the downstream side of a ring conforming generally to the boundary of the jet and supported on struts independently of and downstream of the nozzle exit 3; alternatively, the projections