과냉각수조 내의 제트에 의한 용융우드메탈 미립화에 관한 실적 연구 = Experimental Study of Molten Wood`s Metal Jet Breakup in a Subcooled Water

다국어 초록 (Multilingual Abstract)

The liquid jet breakup has been studied in the areas of aerosols, spray and combustion. The jet breakup depends on several parameters, such as the jet velocity, the inner diameter of the nozzle and the density ratio of the water to the jet. This paper deals with characteristics of the jet breakup according to the jet velocity and the nozzle diameter. In order to consider only hydrodynamic factors, all jet breakup experiments were conducted in non-boiling conditions. In the present study, the wood`s metal was used as the jet material. The jet behavior in the water pool was observed by high-speed camera and PIV technique. All the experiments showed that the jet breakup occurred instantly as the jet contacted with the subcooled water and the fragmented debris moved in radial direction. However, there were some differences between experimental conditions. At the small nozzle diameter, there was no significant difference according to changes in the jet velocity. Generally, the breakup rate strongly depends on the jet velocity but the density ratio affects the breakup behavior most significantly at low jet velocity(< 4.5 m/s). For the larger nozzle diameter, extensive breakup occurred as the jet entered the water pool. It was observed that the more molten wood`s metal is ejected, the debris moved strongly in radial direction. After each experiment, the debris of the jet was collected, dried and sieved to analyze characteristics of the jet breakup. Then, the debris was distributed according to the debris size. For the condition of inner diameter of 6.95 mm and the jet velocity of 2.8 m/s, the debris size of 22 mm gave the largest mass fraction, 39%. For higher jet velocity of 3.1 m/s, the debris size of 14 mm gave the largest mass fraction, 36%. For the nozzle with inner diameter of 9.30 mm, the debris size distribution was different. For jet velocity of 2.8 m/s and 3.1 m/s, the debris size with the largest mass fraction was found to be 14 mm. It means that the debris size decreases as either the diameter or the jet velocity increases.