垂荡浮子式间歇吸水浮射流装置的水动力特性及氧传输机理研究

Dissolved oxygen concentration is an important index of seawater quality. In recent years, the hypoxia of deep sea aggravates due to the effect of seawater stratification etc. The research aims at enhancing the dissolved oxygen concentration in hypoxic deep-seawater with natural oxygen supply method economically and efficiently as the application background. The hydrodynamic characteristics and the oxygen transfer mechanics of an intermittent water-sucking and buoyant jet device with a heaving buoy are investigated using the theoretical, experimental and numerical methods etc. The heaving motions of buoy etc., the hydraulic parameters for intermittent water suck and buoyant jet, and the dissolved oxygen concentrations are measured spatially and temporally. The water particle movement and the turbulence parameters at the wave surface are taken into account for the calculation of the oxygen transfer coefficient; the 3-D mathematical models are conducted consisting of the heaving motion of buoy etc., the intermittent water suck and buoyant jet and the dissolved oxygen transport, and they are used to accurately explore the oxygen transfer behavior considering the effects of wave surface and vertical transport of water body. The intrinsic relationships between heaving motion of buoy etc., intermittent water-sucking and buoyant jet parameters, dissolved oxygen concentrations and wave parameters, geometric parameters of the device are considerably examined. The water temperature and density stratification effects on oxygen transfer coefficient and oxygen supply efficiency are analyzed so as to promote the research process of oxygen transfer between water and air phases. The geometric parameters of the device are optimized to obtain the economical and efficient conditions. The objective is to provide insight into the technical support on oxygen supply research and engineering application in hypoxic deep-seawater economically and efficiently.

溶解氧浓度是重要海水水质指标。近年来，受海水分层等因素影响，海洋深层缺氧范围和程度日趋严峻。项目以深层缺氧海域经济、高效的自然增氧为应用背景，以垂荡浮子式间歇吸水浮射流装置水动力特性及氧传输机理为研究对象，采用理论研究、室内试验和数值计算等方法开展研究。精细观测、计算和分析浮子等垂荡运动、吸水浮射流水力参数和溶解氧浓度的时空变化；将波面水质点运动和紊动特征参数引入氧传质系数，建立浮子等垂荡运动、间歇吸水浮射流和溶解氧输移扩散三维数学模型，精确计算波面氧传质和水体垂向输移共存条件下的溶解氧传输行为；深入探究浮子等垂荡运动、吸水浮射流水力参数、溶解氧浓度与波参数、装置几何尺寸与布置的内在关联，阐明水温、密度分层等对氧传质系数和增氧效率的影响机制，推进水气二相氧传输的研究进程；开展装置几何参数优化设计研究，阐明其经济、高效运行条件。目标是为深层缺氧海域经济、高效的增氧研究和工程应用提供技术支撑。

溶解氧浓度是重要的海水水质指标之一，过低会带来严重的环境生态问题。近年来，受海水富营养化和气候变化共同影响，全球近岸缺氧海域面积逐渐增加，形势日趋严峻。自然条件下，海水表层溶解氧浓度一般较高，海水深层较低。项目组研发了一套垂荡浮子式间歇吸水浮射流装置，利用其增加深层海水溶解氧浓度。项目组利用理论分析、室内试验和数值模拟等方法，对波浪作用下单垂荡浮子和阵列式垂荡浮子间歇吸水浮射流装置水动力特性及氧传输机理进行了观测、计算和分析。发现：（1）随着入射波高增加，单浮子平均垂荡幅度和平均吸水流量增加；随着入射规则波波高/随机波有效波高增加，阵列式浮子的平均/有效垂荡幅度以及平均/有效射流量均增加。（2）随着入射规则波周期增加，单浮子平均垂荡幅度和平均吸水流量增加；随着入射规则波周期/随机波谱峰周期增加，阵列式浮子平均/有效垂荡幅度增加；随着入射波陡增加，阵列式浮子相对垂荡幅度减小，装置相对平均射流量增加。（3）随着吸水高度增加，单浮子平均垂荡幅度和平均吸水流量稍有增加。（4）随着浮子密度增加，单浮子相对垂荡幅度、阵列式浮子有效垂荡幅度和波能俘获效率均呈现先增加后降低的趋势。（5）随着浮子宽高比增加，阵列式浮子相对有效垂荡幅度和波能俘获效率呈增加趋势。（6）浮子相对中心距对菱形排布的阵列式浮子波能俘获效率影响较小。菱形和等腰三角形排布方式下扁平圆柱形浮子相对有效垂荡幅度和波能俘获效率较高。（7）随着浮子相对高度和等效阻尼系数增加，单浮子相对垂荡幅度和平均上行、下行速度均减小。随着等效阻尼系数及其相对值增加，阵列式浮子有效垂荡幅度、相对有效垂荡幅度与波能俘获效率均减小。（8）随着入射波高增加，自由波面氧传质系数增加。随着入射波高、入射波周期及射流速度增加，垂直圆管射流氧传质系数增加。（9）基于符号回归方法，建立并验证了规则波条件下垂直圆管射流氧传质系数预测公式。上述结论可以为深层缺氧海域经济、高效的增氧研究和工程应用提供有力的技术支持和参考依据。