• Journal of Korea Water Resources Association
• /
• v.32 no.2
• /
• pp.153-162
• /
• 1999

In this study, mixing and dilution characteristics of vertical multijet discharged by multiport diffuser into stagnant water are investigated. The results obtained from the experiment of multiport diffuser performed in the three dimensional flume are as follows. As far as merging process of multiport diffuser is concerned, merging starts at about z/l = 3 although merging length is dependent upon stability condition and thereafter lateral temperature distribution becomes gradually uniform which is typical distribution of plane jet. Analyses of experimental data for minimum dilution show that characteristics of minimum dilution are described based on three regions which are jet region where momentum is dominated, intermediate region, and plume region where buoyancy is dominated. Minimum dilution coefficient in plume region of multiport diffuser obtained in this study is 15% higher than that of plane diffuser. This is because individual jet of multiport diffuser entrains more ambient water before merging is occurred, and therefore dilution increases.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.12
• /
• pp.1209-1215
• /
• 2012

Experiments with premixed flames in a tube have been conducted to investigate the transition phenomenon from a laminar flat flame to turbulent motions. To induce this phenomenon, a flat flame is formed in a tube. Then, the local velocity at the center of the flat flame surface is increased using $CO_2$ laser irradiation. The deformed flame front propagates with an increase in the total flame surface and oscillating instability. Eventually, the flame front accelerates explosively, and it shows turbulent flame motions with a strong noise. The dynamic behaviors of the flame front prior to the turbulent motions are analyzed in this study to elucidate this process. The physical model of the process is presented according to observations.