Journal of the Textile Machinery Society of Japan

The tension in a filament yarn twisted by two-for-one twister was calculated theoretically by the use of the twisting conditions and this calculation was compared with experimental results.
1) As results of analyzing the balloon theory, the yarn tension can be estimated from the non-dimensional number Kb/m and h/b. Where K is the proportional constant for air-drag, b is the radius where the yarn leaves the spindle disk, m is the linear density of the yarn and h is the balloon height from the point where the yarn leaves the spindle disk to the snail guide.
2) The region of Kb/m where the yarn leaves from the conical plane decreases with increasing the apex angle of the conical spindle disk.
3) For the larger value of Kb/m, the yarn takes off the upper edge of the spindle disk and the tension is the same as the case where the yarn takes off the cylindrical spindle disk that has the same radius as its upper edge.

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This paper describes the experimental study concerning air-flow characteristics in the weft-acceleration pipe of an air jet loom when forced flow is given to the weft-guide pipe of the nozzle trially made. Central flow through the weft-guide pipe is composed of both flow naturally sucked by the pressurized annular flow, and positively gushed-inflow (forced flow). To study the flow condition useful for acceleration and flight of a weft, the flow in the weft-acceleration pipe was measured with a hot-wire anemometer when M was changed stepwise, where M is the ratio of flow rate of the central flow to that of the annular flow through the nozzle. During the experiments, R, the ratio of the annular-exit area to the central-exit area and Re, Reynolds number of air flow in the weft-acceleration pipe, were kept constant (R=0.343, Re=1.7×10⁴).
The following results were obtained: When M is increased: (1) velocity defect along the axis of the weft-acceleration pipe is reduced. (2) turbulence in that pipe is weakened.
As a result, it is sure that a flow useful for acceleration and flight of the weft is generated. This fact can also explain the reason why the modern tandem main nozzle can achieve steady flight of weft.

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