考虑下渗海水稀释作用的海底热液活动系统数学模型
The model of hydrothermal system with permeating seawater embranchment simulating effect of dilution on hydrothermal flow
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摘要: 在简单巨羽流生成模型基础上,考虑下渗海水对循环热液的稀释作用设计建立了管状模型,旨在讨论下渗海水(在海底普遍存在)对热液循环系统的影响。在保持原模型基本结构的基础上又添加了代表下渗低温海水稀释作用的D区。模型着重对D区中的低温下渗海水(未经反应区加热)与释放区热液的混合,从而对实现热液稀释的作用进行分析。首先建立系统中两个循环体的控制方程,然后在有限条件下对模型求解,并对求解的结果进行实际意义的分析。主要结论包括下渗区D区作为释放区时,D区释放流体的物质流速已明显大于C区中流体的物质流速,下渗区成为另一个喷溢区;如果在烟囱体下部有裂缝或者其外壳的渗透率较高时,对系统所释放流体的温度、物质通量等指标的估算不能再按常规方法单纯地考虑烟囱体的喷口,因为周围的"高渗区"可能是更大的释放区;对于巨羽流系统,由于释放区C区的压力较小,所以不太可能发生上述情况;具有明显低温流的天然系统不可能位于本模型的参数空间;对热液系统发育的不同阶段应采用不同的数学模型。Abstract: The tube model is based on the first model and considers the dilution effect of permeating cold seawater.It adds Zone D which represents lower-temperature permeating seawater to the previous model.The model stresses direct mixing of lower-temperature seawater in Zone D with hot fluid in discharge zone,consequently analyses how the hydrothermal fluid is diluted.First,the control equations of two circulations are cstablished,and then it is tried to find numerical solution of the model under different circumstances.Finally,a series of conclusions are found after analyzing the solutions as follows:Permeating cold seawater can hardly invade the black smoker to dilute the hot fluid,while Zone D may become the next discharge zone when the hot fluid discharges at high speed.If there are fissures at the bottom of the black smoker or the shell it has high permeability,evaluations for the temperature,the mass flux,etc.cannot be achieved by considering the vent of the black smoker solely,as the high permeating zone around the smoker may be another bigger discharge zone.Parameters of natural hydrothermal system with obvious low-temperature fluid hardly belong to the parameter space of this model.Different models should be used at different stages of hydrothermal circulation system.
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