Jet Loom Research Articles

Flow Characteristics in an Air Jet Loom with a Modified Reed and Auxiliary Nozzles

In this basic research for improving the performance of main nozzle of an air jet loom with a modified reed and auxiliary nozzles, the relation between the length of an acceleration tube and jet flow characteristics for 2∼6kgf/cm2 tank pressures has been eamined within both subsonic and supersonic regions of jet speed. Further, the weft drag force by the main nozzle has been measured.The results are as follows : (1) The distributions of jet speed in the subsonic flow region are little affected by acceleration tube length of the nozzle (2) In the supersonic flow region, some effects of the tube length are founded. For nozzles with the accerelation tube length L≥70mm, expansion waves are generated at the nozzle exit, on the other hand, for a nozzle with L= 50mm, compression shock waves occur. (3) In the supersonic flow region, the generation of expansion waves for nozzles withL=70mm causes an abrupt increase in jet diameter and a reduction of the flow speed. However for a nozzle with L= 50mm, significant changes in jet diameter and speed can not be observed owing to the genenration of compression shock waves. (4) The weft drag force is strongly affected by the flow through an accerelation tube. The drag force is smaller as the accerelation tube length becomes shorter.

Flow Characteristics of the Main Nozzle in an Air-Jet Loom

In this research, the jet-flow characteristics under tank pressures of 2 ∼ 6 kgf/cm2 were studied to obtain basic data for an optimal design of the main nozzle in an air- jet loom. Furthermore, wefts were actually inserted in the nozzle and weft traction forces were measured. Axial changes of the nozzle jet speed and jet diameter below the tank pressure at which choking arises at the exit of the acceleration tube are largely different from those above that tank pressure. Choking arises within the upstream region in the acceleration tube (Mach 1), and the Mach number at the tube exit exceeds 1. When this happens, expansion waves occur owing to underexpansion, and the oscillation of compression and expansion waves can be seen in the downstream region. Therefore, the weft drag force F, which represents the weft-flying property in a nozzle, increases in proportion to tank pressure PT. But when the flow is choking at the exit of the acceleration tube, the drag force F becomes nearly constant, even at higher tank pressures.

エアジェットルームのよこ糸加速管内流れ メインノズル導糸管内の強制流れの効果

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.

Comments on “Measuring Beat-Up Force on a Water Jet Loom”

Comments on “Measuring Beat-Up Force on a Water Jet Loom”

Flow Characteristics in Weft-Acceleration Pipe of Air-Jet Loom

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.

Measuring Beat-up Force on a Water Jet Loom

Methods are described for measuring the beat-up force on a water jet loom and the dynamic calibration of the force transducer. Experimental results show that the warm- up time, loom speed, and shed timing have no effect on beat-up force, while the pick spacing and linear density of the filling yam have a considerable effect on the maximum beat-up force and the shape of the beat-up pulse.

Ａｉｒ Ｊｅｔ Ｌｏｏｍにおける流れ現象の２，３の考案

Ａｉｒ Ｊｅｔ Ｌｏｏｍにおける流れ現象の２，３の考案

Experiments of Flow of Air Jet Loom with Air Guides

The characteristics of flows in tubes with different diameters are studied, and compared with flows in tubes with slits.The main results are as follows:(1) The flow in a tube can be divided into two regions by the difference of flow feature.(2) The flow in the first region shows similar features to a free jet flow untill a jet flow from a nozzle reaches a tube wall and the static pressure on the tube wall is negative.(3) The other region is a down stream part of the tube and shows the characteristics of a pipe flow. The effects of the diameter, gap distance between a nozzle and a tube, and the slit are classified.

変形おさ補助ノズル方式エアジェットルームにおける流れ特性 （第１報）メインノズル内の流れ

本研究では, 変形筬補助ノズル方式AJLの緯入れ性能の向上を目的とした基礎的研究として, メインノズル管内の流れを非圧縮性流体の一次元流れとして解析するとともに壁面静圧を測定して, ノズルタンク圧や加速管長がノズル管内流速の変化に及ぼす影響を明らかにした.得られた結果は次の通りである.(1) メインノズル管内流れでは, M=1となって臨界状態を示すスロート部が, ニードル先端部と加速管出口部の2か所で生ずる可能性があり, タンク圧力を変えることにより, これらのスロート部が発生し, ノズル管内流れの様相が特徴づけられる.(2) ニードル先端部が臨界状態になるノズルタンク圧力PTは加速管長に依存し, 加速管長が長くなるほどPTは高い.(3) 加速管出口が臨界状態になるノズルタンク圧力PTは, 加速管長にかかわらずほぼ一定で, 本実験の範囲のノズルでは, PT≒4kgf/cm2である.(4) 加速管出口が臨界状態になる流れでは, 管内流れは常に亜音速の場合と超音速流れを含む場合に分けられ, 加速管長の短いノズルにおいて後者の例が認められる.(5) 本実験の加速管長L=70mmのノズルにおいて加速管内で衝撃波が発生する.

Experiments of Flow of Air Jet Loom with Air Guides

Flow characteristics of air guides of an air jet loom have been experimentally investigated. We compare the flow in air guides with the flow jetted free in atmosphere to clarify the effects of air guides.The main results are as follows:(1) A flow field in air guides can be classified into two regions.(2) The first region is found at the up-stream part of guides and the distribution of the axial velocity along guides shows very similar features to a free jet flow.(3) The other region is at the down-stream part. The axial velocity slightly decreases along guides and the distribution of radial velocity can be expressed by the power law of about 1/6.

Experimental Study on the Flow of an Air Jet Loom with an Air-Guide

As a fundamental study on the flow in a air jet loom with an air-guide, we have investigated the flow characteristics of flow in the tubes with different diameters, and also compared with the flows in the tubes with slits.The main results are as follows : (1) The flow in a tube can be divided into two regions by the difference of flow feature. (2) The fiow in the first region shows similar features to a free jet flow untill a jet flow from a nozzle reattaches on a tube wall and the static pressure on the tube wall is negative. (3) The other region is a downstream part of the tube and shows the characteristics of a pipe flow. The effects of the diameter, the gapdistance between a nozzle and a tube, and the slit are clarified.

Experimental Study on the Flow of an Air Jet Loom with an Air-Guide

The flow characteristics of an air-guide of an air jet loom have been experimentally investigated. We compare the flow in an air-guide with the flow jetted free in atmosphere to clarify the effects of an air-guide.The main results are as follows : (1) A flow field in an air-guide can be classified into two regions. (2)The first region is found at an up-stream part of the guide and the distribution of the axial velocity along the guide shows very similar features to a free jet flow. (3)The other region is at the down-stream part. The value of the axial velocity slightly decrease, along the guide and the distribution of radial velocitics can be expressed by the power law of about 1/6.

Weft Insertion on Air- jet Looms: Velocity Measurement and Influence of Yarn Structure Part I: Experimental System and Computer Interface

An account la given of an experimental system developed for automated data acquisition In air–jet weft insertion. The air–jet–loom simulator and the computer interface for measuring the insertion time, air and yarn velocities, and air pressure ln the system are described.

Air flow in a tube composed of numerous ring plates. (Flow characteristics in air-guide of air jet loom).

The flow characteristics in a tube composed of numerous ring plates of uniform size at an interval of the same clearance are investigated experimentally. The friction coefficients and the radial distributions of the velocity are reported for fully developed flow with different clearances and wall taper angles. The friction coefficient is calculated from the momentum and the static pressure gradient of the flow. The results show that the mean velocity decreases with the axial distance exponentially, and that the wall taper angle at which the friction coefficient is minimum for various clearances is 2°. The radial distributions of the velocity agree with the logarithmic law of rough tubes for an angle of 2° and over.

Tension Fluctuation of Weft Yarn in Air Jet Loom

Tension Fluctuation of Weft Yarn in Air Jet Loom

Jets Injected into Air Guides of an Air Jet Loom

The characteristics of jets injected from sub-nozzles into air guides of an air jet loom were investigated experimentally.Weft-guide system which is composed of air guides with rectangular-shaped passage and sub-nozzles with small two holes was used. It is shown that the flow pattern in steady jetting from single sub-nozzle is classified into 5 regions, and that the velocity profiles at region V display similar distributions independent of jetting angles of sub-nozzles. Furthermore, measured velocity profiles and static pressure in case of steady and pulsed jetting from numerous sub-nozzles are presented.

Jets Injected into Air Guides of an Air Jet Loom

The characteristics of jets injected from sub-nozzles into air guides of an air jet loom were investigated experimentally. Special-reed system which is composed of special reeds with channel-shaped passage and subnozzles each with a small hole was used. It is shown that the flow pattern in steady jetting from single subnozzle is classified into 3 regions, and that the velocity after collision with the interior wall of the air guide decreases more repidly than that of free jet. Furthermore, the measured velocity profiles, turbulence intensities and static pressure in case of steady and pulsed jetting from plural sub-nozzles are presented.

Present Condition of Automation System for Jet Loom Wearing Mills

Present Condition of Automation System for Jet Loom Wearing Mills

A Study on Intermittent Water Jet

Several methods were devised to study the behavior of the intermittent water jet used in the water jet loom, and the effects of the pump pressure, the supplementary air flow along the jet-stream and the water surface tension on the transition of the jet flow pattern, the jet-head velocity and the break-up length are observed, where the break-up length is the distance from the nozzle to a point where the jetstream first breaks its continuity. The followings are the main results obtained:(1) As the jet goes further from the nozzle, its flow pattern changes continuously from the smooth flow to the wavy flow and finally becomes the spray flow. There is a fist-like bump at the jet-head in the wavy flow.(2) The higher the pump pressure, the faster the transition of the flow pattern and the faster the highest jet-head velocity, but the shorter the break-up length.(3) The supplementary air flow retards the transition of the flow pattern and increases the breakup length.(4) The lower the water surface tension, the longer the break-up length. But some surface active agents increase the water viscosity and lower the highest jet-head velocity.

正誤表

正誤表