【作者】 明平剑；

【导师】 王德明；

【作者基本信息】 哈尔滨工程大学 ， 动力机械及工程， 2008， 博士

【摘要】 气液两相流广泛地存在于能源、动力、核能、石油、化工、制冷、冶金、航天和环境保护等许多工业领域中,研究气液两相流运动规律对工业设计具有重要指导意义。目前对气液两相流动进行很多的理论研究和实验研究,数值研究方法较少,而且主要依赖商业软件或者在结构化网格下进行,使得其应用受到限制。本文主要展开了基于非结构化网格气液两相流动数值模拟方法的研究。研究了基于非结构化网格通用输运方程的数值求解方法,包括输运方程的离散格式,边界条件处理方法,压力速度耦合SIMPLE求解方法,详细讨论了影响界面流量计算的重要因素。对不同物性材料耦合流场及温度场求解方法及实现方式进行了讨论。研究了大型稀疏线性方程求解方法。研究表明在计算流体力学(CFD)中,线性方程组的求解方法占总CPU时间的60%以上,提高线性方程组的求解速度是提高数值计算总体性能的关键所在。本文研究了一种聚合型代数多重网格方法,并开发了相应的计算程序,提高了线性方程组的求解速度,该方法的另一个特点是可以方便的实现并行处理,这也是本文所关心的另一个重要特性。基于非结构化网格开发了流体力学数值计算平台,在此平台上对一些经典的算例进行了验算,计算结果与理论和实验吻合很好。同时与大型商业软件计算结果进行了对比,本文开发的平台各方面性能表现良好。详细研究了气液两相流动的双流体模拟方法,包括气液两相流的湍流封闭模型,相间作用力模型以及相变模型。同时还对轴对称数值计算方法进行了研究,并将此模型添加到数值计算平台中,节省了计算资源,提高了计算性能。本文开发了基于MPI的并行计算模块,得到了理想的加速比,可实现对大规模实际问题设计计算或者流动细节进行理论研究,。更多还原

【Abstract】 Gas-liquid two phase flow phenomena are present extensively in industries of energy, nuclear, oil, and chemistry. Research on two phase flows is meaningful to make guideline for industry design. There are a lot of experimental and theoretical researches in the literature. However, numerical studies are less published and reports in this area are mainly focused on applying the commercial software or within the framework of structured grids which has limited applications for two phase flows. The present thesis focuses on the development of numerical methods for gas-liquid two phase flows with unstructured grids.Based on the experiences in Computational Fluid Dynamics (CFD), the linear equation solver takes more than 60% CPU time of the whole process, therefore acceleration of the linear equation solver is a key element in enhancing the whole performance of CFD. An agglomeration algebraic multi-grid method is developed and implemented in the solver which accelerates the linear equation set solution. Another advantage of this linear equation solver is that it is convenient for parallel computing, which is also the purpose of this research.Numerical algorithm for general transport equation based on unstructured grid is presented, which includes discretization, boundary condition and velocity-pressure coupling. Some factors influencing the face flux calculation are also discussed in detail. Couple solver of multi-material is constructed and its implement is also given.An N-S equation solver based on unstructured grids is developed. The solver is validated in a number of classical flow problems and the results agree well with other experimental data in literature. Comparison of present solver with commercial software Fluent shows that the developed solver works well.Two-fluid method of gas-liquid two phase flows is discussed in detail, including turbulent enclosure model, interfacial force model and phase change model. Meanwhile the axi-symmetric model has been implemented into the solver and used to save resources and enhance the performance for axi-symmetric flows. In order to simulate detailed large scale industrial problems, the parallel computing method based on MPI has been developed and ideal speedup is achieved.更多还原