The Atomization Characteristics of Ethanol Like-Doublet Impinging Jets

• Main Authors: Shun-Jie Yang, 楊順傑
• Other Authors: Wei-Hsiang Lai
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/77728433362515478221

碩士 === 國立成功大學 === 航空太空工程學系碩博士班 === 93 === 　Impinging jet atomization is mainly used in liquid rocked proportion systems, including like-doublet and unlike-doublet injectors. The latter is usually applied to bipropellant small-scaled liquid rocket, which uses storable and hypergolic propellants. In this research, 95% ethanol was used as the working fluid to simulate the impinging jets. The orifices of the injector element are 0.3, 0.5, and 0.7 mm in diameter, impinging angle is set to be 60°, 90°, and 120° respectively. Main parameters of atomizing performance are discussed, such as jet velocity, impinging angle, jet diameter and ambient pressure. The results are also compared with previous research. 　In liquid shape mode, six distinct flow patterns can be observed, and the perforated film doesn’t appear. The larger impinging angle, the lower threshold jet velocity of mode transition is observed. 　Regarding the liquid film size, the aspect ratio decreases with increasing impinging angle. One empirical equation can be used to calculate the tangential angle, and the equation induced by Ibrahim et al.[8] can figure out the film length by multiply a constant. 　When the impinging angle reaches 60°, there is a sudden increase of mean drop size during the increment of jet velocity. The SMD appears to be inversely proportional to the jet diameter until film shape transit to open mode. The SMD of unlike-doublet impinging is highly influenced by the surface tension of liquid. 　High ambient pressure has no effect on film size, but it causes the liquid shape change mode in lower jet velocity. In higher ambient pressure, smaller SMD value is measured before the liquid film transit into open mode. When the jet velocity approaches 20 m/s, the SMD of water-like impinging jets reach 100 μm, which is independent of ambient pressure from 2 to 9 bar.