Nozzle effect on air intake in airjet weaving

Airjet loom is a very good alternative to other weft insertion systems, but its major drawback is its high power consumption, say SB Mhetre and Vishal C Yadavwho, who reveal some researches on main nozzle characteristics of airjet weaving machines.

In weaving, airjet weaving is a well known technology because of its operational speed and precision. But enormous consumption of air and, consequently, increased manufacturing cost is the main drawback of the airjet looms. Therefore, many research works were addressed to optimise main nozzle geometry and its functional parameters. Developments of measuring devices, photographic technology, control devices and personal computers were pressed into service to achieve research work in the field of airjet weft insertion. The computer model also has facilitated to solve all types of equations. Those developments have helped to design the main nozzle with minimum air consumption and achieve higher weft insertion rate as compared to other weaving technologies.

Effect of main nozzle

Adanur and Mohamed carried out a qualitative analysis of air flow in a single nozzle airjet insertion. A dynamic air velocity measurement shows that air velocity depended on two variables, i.e., distance and time. A dynamic air velocity increases with time (distance constant) and decreases with distance from the nozzle. The slotted rigid, plastic tube is used to guide air in the experimental system. The tube length is 3.35 mm in air velocity instrument.

At the end of tube suction created by vacuum cleaner is to pull inserted pick out of the tube. They use constant temperature anemometer and hot film probe for the measurement, which is based on convective heat loss from the electrically heated sensor caused by the flow of air surrounding the sensor. The rate of cooling and therefore the change in resistance of the film was nearly proportional to the square root of surrounding air velocity. The change in resistance is converted into the DC signal. The air velocity is determined according to the volt velocity calibration curve.

According to a study of G M Ye D and F Shen, the main nozzle is divided into four parts (tubes). This allowed analysing detailed airflow parameters of each tube, and introducing a method of experiment to test the airflow velocity in the exit nozzle and weft tension in the main nozzle. On the basis of fluid dynamics, the pull force formula of main nozzle on an airjet loom was determined in this paper. The theoretical findings agreed well with the experimental.

The airjet loom is popular in the textile industry because of its high productivity, convenient controllability, and wide variety of products manufactured from it. In order to improve airflow efficiency, many researchers have studied this, using the quantitative analysis method with different paths in the airjet weft insertion of the airjet loom.

Despite several decades of intensive research, the varieties of friction coefficient values of yarn, nozzle shape and working accuracy of the nozzle continue to make the theoretical arithmetic hard to predict, and so there are always some differences between the calculated and measured values. For this reason, this paper also employed theoretical analysis and experiment to explain how each parameter of the main nozzle affects the pull force of the airflow on the weft (hereinafter abbreviated as PF). Based on this experiment, they have drawn conclusions that structure of the main nozzle and its working accuracy are important to the pull force (PF). Decreasing the diametre of the main nozzle can reduce energy consumption; whereas increasing the length of the thread tube can increase the PF. As the trend of airjet loom is towards high speed, the main nozzle should be the main subject of future research. The inlet of the thread tube is a bottleneck of the main no