Air jet weaving is the most productive weaving technology with a speed of up to 1,200 weft insertions per minute. Since there are no moving parts in the weft insertion process, this technology is very reliable. However, the high productivity comes at the price of high energy consumption for weft insertion with compressed air. In view of rising energy costs and the carbon dioxide emissions associated with energy generation, it is important to reduce compressed air consumption and also increase productivity.
One of the most important components for weft insertion is the main nozzle system, and weaving machines are usually always equipped with several main nozzles. The problem here is that with multiple main nozzles, only one is parallel to the reed channel, while the others are inclined to the reed channel. As a result, a lot of compressed air is lost to the rear or above the reed and, at the same time, weft insertion errors are caused by unfavorable flow conditions.
In the IGF project "Energy saving nozzle", a new main nozzle system with a single nozzle and multiple feed pipes is being developed. This nozzle has only a single acceleration tube, which is optimally positioned for weft insertion parallel to the reed channel, providing the basis for significant advantages:
> higher energy efficiency due to lower compressed air consumption.
> lower material costs by avoiding the need for special reeds, and
> higher productivity due to the possibility of double weft insertion.
Due to the retrofittability, a very large market can be addressed. Numerical simulation is used as the central development tool. Computational Fluid Dynamics (CFD) simulations are used to analyze the mode of action and flow conditions of the reference nozzle and to simulate and evaluate different variants of the proposed main nozzle design. Furthermore, a simulation model will be developed to calculate the weft insertion of a yarn with consideration of the yarn-air flow interaction. The CFD simulations are verified by using state-of-the-art measurement technology (particle image velocity and high-speed camera technology). The most promising variant is produced and tested as a functional sample.
