A Study on an Air-Jet Loom with Substreams Added

Abstract

For scrutinizing the motion of weft gushed out and propelled by air stream, the physical (especially aerodynamic) properties of air jet and weft yarns are examined. An equation of motion for weft on an air jet loom is then derived, leading to the numerical solutions in several cases. The followings are some of the results: 1) The axial velocity of air jet is approximated fairly well by the following formula excepting the core region: V=BV0; /(x-A) where A and B are constants, V0; the initial jet velocity, x the axial distance from the nozzle exit to any point. 2) The coefficient of friction of spun yarns in air stream is approximated by Cf; =0.02+1/(V'+2) where V' is the relative air velocity to the yarn in m/sec. 3) In case where an air jet loom utilizes a measuring drum for yarn reserving, the drag due to yarn ballooning is as large as the air thrust. In order to minimize this harmful effect, a suitable cover should be set around the drum. 4) As the time necessary for the yarn to travel for some given distance is rather long in the region where the starting acceleration is not large, the initial jet velocity V0; should be quite large, say over 200m/sec.