Flow angle at exit of the nozzle is the most important factor in designing the stator. Since diffuser has been design in conjunction with the impeller it has the best flow angle and inlet cross sectional areas that produce the best performance. The multi nozzle was design in such way that to replicate diffuser geometry as close as possible. The figure 2a shows design of multi nozzle and figure 2b represents single nozzle. Two types of nozzle were design during the course of this project. Where Δ r the radial distance between nozzle exit and the rotor tip, α is the flow angle and the b is height of nozzle. In fact, no single nozzle design is superior in all applications. The different nozzle designs which are commonly used in industry for coaxial application of gas jet during LBC are presented in Figure 9. Misalignment causes gas to flow across the top of the cut zone, which can lead to undesirable burning of the cut edge, and a poor quality cut. The alignment of the nozzle with the laser beam has a significant effect on the quality of the cut. On the other hand, a nozzle with large diameter supplies insufficient gas flow to eject molten material, and results in high gas consumption. A nozzle with a small diameter creates difficulties in alignment and localizes the gas, resulting in a rough edge. The diameter of the nozzle orifice ranges between 0.8 and 3 mm, depending on the material and the workpiece thickness. In LBC, the design of the nozzle and its orifice determines the shape of the cutting gas jet which significantly affects the quality of the cut. The nozzle has three main roles: to guide the gas coaxially with the laser beam, to reduce the pressure around the lens to minimize lens movement and misalignment and to minimize turbulence in the met pool by stabilizing the pressure on the workpiece surface. The air nozzle preferentially reduces longer hairs, especially S3 hairs ( Table 7.2). Generally, the distance between the nozzle and the front roller is around 10 cm for the best results. Placing the nozzle too close to the front roller would disturb the spinning triangle and affect the yarn formation process itself. An operating air pressure around 0.5 bar (gauge) is found to be sufficient to reduce it. The distance between the nozzle and the front roller, the angle of air inlets and the yarn channel diameter play decisive roles in the efficiency of hairiness reduction. The air-drag forces acting on the protruding hairs fold and wrap them around the yarn surface ( Fig. 7.19). The swirling airflow has three components, namely tangential, axial and radial, the last being very low in magnitude. the yarn undergoes a false twisting action. The yarn coming from the front roller is partially untwisted on the upstream and then re-twisted on the downstream, i.e. The airflow issues from the nozzle in an upward direction, i.e. A Z-nozzle should be used for Z-twisted yarn. It is an air-vortex type of nozzle which creates a swirling airflow as shown in Fig. 7.18. Since the nozzle is the heart of the process of reducing yarn hairiness, its design plays a vital role. Compressed air is supplied to the nozzle through pipes with a pressure regulator and an air filter. The nozzle has to be placed such that the front roller nip, the axes of the nozzle and the yarn lie in a straight line. An air nozzle is placed below the front roller and the issuing fibre strand passes through it before reaching the yarn guide eye ( Fig. 7.17). Nozzle-ring or jet-ring spinning is a recent innovation, which has until now been in the research stage. There is a stop on the inside of the nozzle that forms an airtight seal when the tube is fully inserted into the nozzle. ![]() 4.4c), therefore, the external diameter of the tube must be less than the internal diameter of the nozzle. The nozzle is inserted over the tube ( Fig. The female flared fitting of the BSP nozzle butts against the male BSP coupling. C.īSP (British Standard Pipe) coupling fitting. The use of a JIC nozzle may be required to mate correctly with a flared end of the tubing. The male flared fitting of the JIC nozzle butts against the female JIC coupling. ![]() The JIC nozzle has a male flare at the top that will mate against the female JIC coupling on hose and tube assemblies. 4.4a), so the external diameter of the nozzle must be less than the internal diameter of the hose. The nozzle is inserted into the hose ( Fig. Courtesy of Tube Clean GmbH, Hinwil, Switzerland A. The top row shows the actual nozzles, while the schematics in the bottom row show the nozzle configuration during cleaning. Examples of nozzles and configurations for cleaning.
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