Optimization Of Local Structure And Analysis Of Jetting Performance Of Main Nozzle In An Air-Jet Loom

The technology process of weft insertion drives the rapid development of air-jet loom, and the main nozzle is the key of weft insertion motion. The performance of main nozzle has a direct influence on efficiency of air-jet loom and the quality of fabric. According to the references in home and abroad, most of research on main nozzle concentrated at test and analysis of flow field. However, there is seldom dealt with on structure optimization of the main nozzle.This dissertation uses HTS1-1C main nozzle as the object to analyze the structure parameters of subsonic acceleration zone which consists of nozzle needle curved surface and taper. Firstly, section of needle curved surface is described by equations, a 3-D model of main nozzle is constructed by Pro/E and meshed by HyperMesh, then, boundary conditions of the grids are set up. After that, Fluent is used to simulate the interior flow field of the established model, then the equation of best performance of weft insertion in three supply pressure is obtained. On this basis, affects of the interior flow field of main nozzle caused by taper's change are analyzed. Finally, according to the analysis of the interior flow field of main nozzle, the optimal parameters combinations of subsonic acceleration zone are obtained in several supply pressure.During the study of previous and this work, the velocity of projection of acceleration tube is relative low in low supply pressure, otherwise, in high supply pressure, there are velocity and pressure jump in the projetion of acceleration tube. According to the problem, this dissertation provides a method to control the velocity and pressure of the projection of acceleration tube by changing throat area of the main nozzle. Through analyzing of simulation result, it shows that when the velocity of projection of acceleration tube is low, expanding throat area could increase the velocity of projection of acceleration tube and mean velocity and pressure in the acceleration tube, so that it can increase the weft insertion force. While the velocity and pressure change rapidly, decreasing throat area could reduce the velocity of projetcion effectively.Based on the previous study, the structure of main nozzle is optimized further and the optimal structure of main nozzle is obtained in the supply pressure of 0.3MPa, 0.4MPa and 0.5MPa in this dissertation. The optimal structure combinations reach the design goals of the main nozzle, and this conclusions have some significance on design and manufacturing of main nozzle.