Dynamic Characteristics of Spray Droplets with Side Jet Impingingment

• Main Authors: Ming-Long Lin, 林明龍
• Other Authors: Muh-Rong Wang
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/29966599568580082995

碩士 === 國立成功大學 === 航空太空工程學系 === 89 === An experimental investigation on the effects of radial and tangential impinging jets on the sprays is conducted in the research program. Experiments are performed under room temperature and atmosphere pressure. The Monarch Model-128 hollow cone spray provides the based line data. Two types of the external atomization jets are applied the spray jets: the radial air impinging and the tangential air impinging. The atomizers are operated under the water injection pressure 4kg/cm2 and the air injection pressure 5kg/cm2. The sprays are measured by Insitec Particle Sizer and Phase Doppler Particle Analyzer(PDPA). Results show that the impinging jets can be used to control the spray angle. For example, when applying the radial impinging jet with 6 injection ports, the spray angle reduces from 60 degree to 48 degree. It further reduces to 38 degree when applying radial imping jet with 12 injection ports. Injection of tangential air has wider spray angle than the case with the radial impinging. For example, the tangential jet with 6 injection ports produce the spray angle of 70 degree which is wider than the case with radial impinging jet with 6-ports. Similar effects happened to the 12-ports case. It seems that the tangential air increases the radial velocity of the spray and hence the spray angle becomes larger. Results also show that the impinging jets reduces the mean diameters of the spray. For example, at Z=3cm, the sauter mean diameters (SMD) of the sprays are 78μm and 58μm for the cases of radial impinging jets with 6 and 12 ports, respectively. On the contrary, the SMD’s of the sprays are 55μm and 75μm for the cases of tangential jets with 6 and 12 ports, respectively. Analysis on the data show that the big droplets are moved to the outer region of the spray when the tangential jets are applying to the spray. Hence the tangential jets result in the increase of the radial velocity and the redistribution of the spray droplets.