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流动稳定性涉及较为宽广的研究领域和很多工程实际问题.层流转捩为紊流,是由于层流流动失稳所致,判断失稳与否,则采用稳定中性线和临界Reynolds数的标准加以判断,其对应的流动介质为清水,亦即单相的Newton流体,而对于江河中广泛存在的高含沙水流,在传统的流动稳定性理论中则没有讨论,该文就是补充这方面的不足.研究发现,对于高含沙水流等非Newton流体,层流转捩为紊流以及紊流溃灭再次转为层流,其不仅主要取决于惯性力与黏性力的比值——临界Reynolds数,而且还取决于这种非Newton流体中含沙量的大小、含沙量的分布形式、含沙颗粒粒径的大小以及含沙颗粒的重度等多种因素.研究结果为解释河流中的“浆河”现象、挟沙水流湍流强度及湍流结构的变化趋势提供了一些重要的学科依据.
Flow stability involves a wide range of research areas and many practical problems.Laminar flow turbulence is due to laminar flow instability due to determine the instability or not, then the use of stable neutral line and the critical Reynolds number of standards It is judged that the corresponding flow medium is clear water, that is, the single-phase Newton fluid. However, in the traditional theory of flow stability, there is no discussion on the high-concentration flow of water that is widely present in rivers, which is to supplement this aspect The results show that for non-Newton fluids, such as high-concentration water flow, laminar flow turbulence and turbulence collapse again turn into laminar flow, which not only depends on the ratio of inertial force to viscous force-the critical Reynolds number , But also depends on the non-Newton fluid sediment concentration, the distribution of sediment concentration, the size of the sandy particle size and the severity of sandy particles and other factors.The results of the study to explain the There are some important disciplinary bases for the phenomenon of “slurry river”, the intensity of turbulent flow and the trend of turbulence structure.