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固液系と液液系における蒸気膜崩壊機構

固-液和液-液系统中的汽膜塌陷机理

基本信息

批准号：
08216213
负责人：
菊地義弘
金额：
$ 1.92万
依托单位：
Hiroshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
1996
资助国家：
日本
起止时间：
1996 至无数据
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-08216213/
关键词：
蒸気爆発蒸気膜崩壊固液系液液系圧力波整合崩壊

项目摘要

1.固液系については,電気炉で600℃まで加熱した銀試験体を,サブク-ル度30Kの水中で浸漬冷却し,蒸気膜整合崩壊時の現象をビデオカメラで撮影するとともに系の圧力変動を同時測定し,蒸気膜崩壊とその後の急激な気泡成長による急速非平衡熱伝達過程を検討した.その結果:(1)整合崩壊時に発生する圧力パルスには,第1ピーク圧が最大になる場合(タイプA)と第2ピーク以降に最大圧力が現れる場合(タイプB)とがあり,タイプBの最大圧力が著しく大きくなる.最小膜沸騰過熱度△Tminが小さい領域でタイプBの発生確率が高い.(2)最初の蒸気膜崩壊直後に生成される蒸気塊はタイプBの方が大きくなる.この蒸気塊の再凝縮過程で生じる急速な崩壊に起因して大きな圧力パルスが発生する.(3)蒸気膜崩壊の伝播崩壊の伝播速度は最小膜沸騰過熱度が小さくなるにつれて大きくなる傾向を示すが,広い範囲に分散することかわかった.2.液液系では,所定の温度まで加熱した溶融すず(5g,初期温度th=300〜800℃)をサブク-ル度(△Tsub=20〜80℃)の水中に落下して液液接触実験を行い,蒸気爆発の発生要因とその伝播過程およびその発生限界を検討した.その結果:(1)蒸気爆発の発生下限界は,液液接触界面温度が自発核生成温度となる溶融金属温度とよく合う.また,蒸気爆発の発生確率は△TsubとThが大きい領域で高くなる.(2)蒸気爆発には激しい場合と穏やかな場合があり,後者はThが小さい領域で生じる.(3)高温金属表面の一部で生じる蒸気膜の局所崩壊が,蒸気爆発のトリガーになる.局所崩壊直後に生成される急成長気泡とその急速凝縮とが,液滴全域に崩壊が伝播する端緒となる.以後の伝播過程では,周期的な圧力パルスが発生し,溶融金属の大規模な変形と細粒化はこの圧力ピーク直後に起こる.最大ピーク圧力は第3〜5ピーク間に現れることがわかった.

1. In solid-liquid system, the silver sample was heated at 600℃ in an electric furnace, immersed in water at 30K, and cooled. The phenomenon of vapor film integration collapse was studied. The pressure variation of the system was measured simultaneously. The rapid non-equilibrium heat transfer process after vapor film collapse was discussed. The results are as follows:(1) The pressure generated during the integration collapse is the maximum pressure in the case of the 1st peak pressure (A) and the maximum pressure in the case of the 2nd peak pressure (B). The minimum film boiling superheat △Tmin is small and the yield is high. (2)After the initial vapor film collapse, the vapor mass is generated. The rapid collapse of the vapor mass during the re-condensation process is caused by high pressure. (3)The propagation rate of evaporation film collapse is smaller than the minimum film boiling superheat. The tendency of evaporation film collapse is larger than that of evaporation film collapse. 2. The liquid-liquid system is heated at a given temperature.(5g, initial temperature th=300 ~ 800℃) In the process of falling into liquid contact with water at temperature of 300 ~ 80℃, the main causes of steam explosion and the propagation process are discussed. The results are as follows:(1) The lower limit of vapor explosion development is: the liquid-liquid interface temperature is the temperature of spontaneous nucleation and the temperature of molten metal is the temperature of fusion. The accuracy of vapor explosion is high in the large field. (2)In the case of steam explosion, the situation is different, and the latter is different from the small field. (3)A part of the high temperature metal surface produces vapor film, and the vapor explosion occurs. The rapid growth of bubbles and rapid condensation after the collapse of the liquid droplets. In the future, the propagation process is reversed, the periodic pressure is generated, and the molten metal is formed on a large scale and refined. The maximum pressure is between 3 and 5.