Development of fluidic weft insertion sensors

Measuring the speed of weft insertion into the shed of warp threads on a jet loom is a difficult problem, sometimes described as nearly impossible to solve. A solution was found by the author in an inversion of the basic principle of shuttle-less air-jet loom, i.e. using the dragging action between the weft and air flow. Initially, the analogy went as far as using also an air jet – issuing from a nozzle through which the weft passes – as the flow influenced by the weft motion. Recent studies, described in this paper, have shown that better performance is obtained by the weft/air interaction in long, small-diameter channels.