Atomization Performance of Mutiple-Orifice Nozzle Under Swirler Effect

• Main Authors: Ya-Shuan Han, 韓亞軒
• Other Authors: Muh-Rong Wang
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/85207807258459689376

碩士 === 國立成功大學 === 航空太空工程學系碩博士班 === 92 === 　　This research program investigates the effects of multiple orifices on atomization performance of an air-assist atomizer with swirler effect. The function of the swirler is to enhance the lateral momentum of the liquid phase to, produce a prefilming atomization mechanism. Experiments compare the atomization performance of the swirlers with length of 10mm, 20mm and 30mm, respectively. The orifices of the nozzle are designed in a singularity configuration with 0.8mm in diameter of the nozzle. There are 4, 6 and 8 orifices and designed in different patterens. The atomizer’s materials are stainless steel and plastic. The particle size of the spray is measured by INSITEC RT-sizer . 　　Results show that the atomizer with 10mm swirler has better performance because it loses less kinetic energy due to the shorter channel in the swirler. As a typical example, the mean particle sizes produced by the atomizers with 10mm, 20mm and 30mm swirler are 6.30μm, 6.48μm and 7.06μm, respectively. Results also show that the stationary-type swirler has better atomization performance compared to the rotating one. The kinetic energy of atomization gas is partially transfer to the rotating swirler, hence the atomization energy transferred to the liquid phase is less. It turns out that the mean particle size and the standard deviation（σ）associated with the stationary swirler are smaller. The geometric arrangement of multiple orifices also influence the atomization performance. Results show that the nozzle with eight orifices arranged in double-crossing pattern (ie, cn8-nozzle) results in the best atomization performance. For example, the cn8-nozzle produces spray with mean particle size and standard deviation of 5.82μm and 8.95μm, respectively, under test condition of (Pa , Pw)=(6.0,5.0) bar. Tests on the nozzle material show that the nozzle with stainless steel has better atomization performance. It seems that stainless steel is hydrophilic and is useful in the enhancement of the prefilming mechanism of the liquid phase during the atomization processes. In summary, the nozzle made of hydrophilic material with doubt-crossing orifices and short swirler has the optimum atomization performance.