Application of submerged water jets to the decomposition of organic compounds with the aid of compressibility effects in bubbly water flows.

目前的研究已经取得了发展的替代空化水射流设施，使有机化合物在污染的水分解在显着较低的喷射操作压力相比，通常使用的淹没水射流。在目前的工作中的一个基本思想是利用冲击波定位的气泡崩溃，这是预计将导致有效的分解溶解在水中的有机化合物的发生。研究结果如下：1.当气泡流通过水射流喷嘴时，满足产生激波的条件时，溶解在水中的有机物的分解速率增加，虽然在目前的实验中所达到的增加率仍然保持在低于最初预期水平的范围内。2.发现两种补充手段对于实现超声速泡状流是有用的，适度低的流速范围;一种是使用人工产生的微泡，另一种是在喷嘴上游的流动中引入轴对称旋转运动。对气泡在水中生长的数学和数值分析表明，空化初生可以在高于所谓的临界压力的环境压力下发生，低于该临界压力时，空化初生条件已知是满足的.将本实验室新近发展的一组描述液-气混合物运动的空间平均模型方程应用于收敛-扩张喷管流场的计算，发现它是一种很有前途的方法，可用于含空化的高速液体流场的实际计算。

The present research has been made to develop an alternative cavitating water-jet facility which enables to decompose organic compounds in contaminated water at significantly low jet-operating pressures compared to customarily used submerged water jets. A basic idea in the present work is to utilize shock waves for localizing the occurrence of bubble collapse, which is expected to cause the efficient decomposition of organic compounds dissolved in water. The results of this study are summarized as follows.1.The decomposition rate of organic compounds dissolved in water increases when the bubbly flow through the water-jet nozzle meets the condition to generate shock waves, although the rate of increase attained so far in the present experiments remains within an extent lower than the initially expected level.2.Two supplemental means are found to be useful for realizing supersonic bubbly flows in a moderately low range of the flow velocity ; one is the use of artificially generated microbubbles, and the other is the introduction of axisymmetrically rotating motion in the flow upstream the nozzle.3. Mathematical and numerical analyses of the bubble growth in water show that the cavitation inception can occur at an ambient pressure higher than the so-called critical pressure below which the inception condition is known to be satisfied.4. A set of space-averaged model equations describing the motion of liquid-gas mixtures, which was recently developed in our laboratory, is applied to the computation of convergent-divergent nozzle flows, and is found as a promising method for the practical calculation of high-speed liquid flows with cavitation.