【作者】 邵磊；

【导师】 王颖； 周孝德；

【作者基本信息】 西安理工大学 ， 环境工程， 2008， 硕士

【摘要】 各种热电、核电厂排出的热污(废)水在直接进入环境流体之前,以孔口浮射流的形式释放污水并确保污水在排污口快速混合非常重要。因此,精确的了解和预测浮射流的特性与混合状况有很重要的意义,而用数值模拟的方法来全面研究环境流体中射流的混合过程则是一个重要的技术手段。在回顾射流的理论,并对目前的各种紊流数值方法进行了讨论分析的基础上,本文有针对性的研究了在同向流动环境中使用多孔扩散器进行热废水排放的情况,对其近区的流场和温度场特性进行了数值模拟,分别利用FLUENT软件中的RNGκ-ε模型和雷诺应力RMS紊流模型,并用有限体积法和SIMPLE法进行模型方程的求解,得到了不同流速比和不同射流温度下的流场和温度场;浮射流的轨迹线;轴线上温度和速度的衰减规律;浮力对射流轨迹线的影响,并对多孔热水浮射流中对流态具有重要影响的流速比和孔间间距进行了探讨,分别计算了不同流速比情况下的不同孔间间距的流速分布和温度分布,得到了一些很有价值的射流规律和结论。本文利用多种数学模型对复杂的三维流场进行了数值模拟,为课题后期的实验研究提供了参考对照的依据,对研究各种热、核电厂热污(废)水排入环境水体有一定的实用价值,并能为冷却水工程提供理论分析依据。最后对所做的工作和成果进行了总结,指出了论文的不足,并对下一步的工作做出了展望。更多还原

【Abstract】 Before the thermal wastewater of the thermal and nuclear power plants intrudes into the environmental water, it is important to ensure that high initial mixing is achieved in the vicinity of the discharge structure by releasing the contaminated fluid through orifices and in the form of buoyant jets. Therefore, accurate understanding and predictions of the behaviour of a buoyant jet and its mixing characteristics are desired.In this research, jet theories were reviewed different mathematical modeling technologies of turbulent flow were analyzed and valued, and then I took the numerical model research of the velocity and temperature distribution of near-field flow behavior when using diffusers to discharge waste water. In the mathematical model research, with the reference to software of FULENT,standard two equation k-εturbulent model、the Renormalization Groupk-ε(RNG k-ε)model and Reynolds Stress equation(RMS) model are adopted.At the same time,the model equations are solved in finite volume and SIMPLE methods. I have got the velocity and temperature field, buoyant jet trajectory, temperature attenuation along the axis, buoyant jet trajectory impacted by buoyancy force under different velocity ratio and different jet temperature. The velocity ratio and ports space, which have very important effect on flowing behavior in multiport thermal wastewater jet, were investigated and speed and temperature distribution were calculated under different ports space of various velocity ratio. And we can also get some jet laws and results.In this parer,I use different models simulated the complicated 3D flow , it has a referred value for the later experimental study. It is valuable to study the regulars of thermal wastewater in the thermal and nuclear power plants intrude into the environmental water. It can alsoprovide some theoretic foundations for cooling water projects.At the last, all the work and fruits in the paper were summarized and the defects and further work were elaborated.更多还原