船闸阀门突扩体廊道掺气水流数值模拟研究

发布时间：2018-04-15 11:18

本文选题：船闸 + 阀门　；参考：《重庆交通大学》2014年硕士论文

【摘要】：近二十年来，我国水利建设及河流水资源综合开发利用进入了快速发展时期。兴建水利枢纽，带来的效益之一是改善了航运的条件。而船闸作为水利枢纽通航建筑物的主要型式，以其技术成熟、工作稳定、运行维护方便等优点应用最为广泛。随着一大批高坝枢纽的建设，船闸的工作水头也在大幅提高，同时为提高其适用性，高水头和超高水头的船闸不断出现，逐渐成为现代船闸的发展趋势。但高水头船闸的阀门段廊道空化问题一直是制约船闸安全运行的巨大隐患，空蚀破坏是船闸输水廊道中常见的破坏。现今用于改善空化条件的措施有两点，一是优化阀门段廊道体型，如船闸阀门段廊道新型上下突扩体型是一种比较成熟的廊道最优方案，相比平顶型和顶扩型，其不仅满足了高水头船闸输水的要求，而且很大程度减少了空蚀空化问题，但该廊道体型仍然存在一定范围的空化区；所以须采用到另一种减蚀措施——增设掺气系统，通过掺气来解决空蚀空化问题。物理模型试验是研究船闸阀门段廊道掺气水流最主要的手段，，而关于廊道掺气数值模拟几乎无人涉及。由于阀门门楣的掺气条件复杂，不易数值模拟，因此本文重点以数值模型的研究手段对阀门后上下突扩体型廊道的掺气水流的水力特性进行了数值模拟，以国内某典型高水头船闸阀门段廊道为建模对象，结合物理模型试验资料和相关理论知识，建立设置了台阶状跌坎和升坎的新型突扩体几何模型，选用Fluent软件中的VOF模型和Mixture多相流模型，分别对阀门段廊道掺气前后进行二维数值模拟。最后得到以下四个主要结论： ①新型突扩体廊道属于更进一步的优化体型，提高了廊道内的压力，相比于船闸其他体型，其廊道底板、升坎等多个部位的空化溃灭区得到可观的改善，通过本文数值模拟验证了其良好的减蚀效果； ②新型突扩体型廊道在阀门0.4、0.5、0.6和0.7开度时，在廊道顶部产生一定范围的负压区域，易产生空化；在阀门0.3和0.4开度时会在跌坎部位第一、二级台阶处产生少许负压，形成空化源； ③阀门0.4开度，廊道顶掺气速率达到18m/s时，原廊道顶负压区域全部转化成正压; ④掺气水流基本遵循了掺气速率越大，则掺气浓度越高，负压改善越好的规律。
[Abstract]:In the past twenty years, water conservancy construction and comprehensive development and utilization of river water resources in China have entered a period of rapid development.One of the benefits of building a hydro-junction is to improve the conditions for shipping.As the main type of navigation building, ship lock is widely used with the advantages of mature technology, stable work and convenient operation and maintenance.With the construction of a large number of high dam hubs, the working head of ship lock is also greatly increased. In order to improve its applicability, the lock with high water head and high water head appears constantly, and gradually becomes the development trend of modern ship lock.However, cavitation in valve section of high head shiplock is always a great hidden danger to restrict the safe operation of lock. Cavitation damage is a common damage in waterway of shiplock.At present, there are two measures to improve cavitation conditions. One is to optimize the type of valve corridor. For example, the new type of up-and-down expansion of valve corridor is a more mature corridor optimal scheme, compared with flat top type and top expansion type.It not only meets the requirement of transporting water in high head lock, but also reduces cavitation problem to a great extent. However, there is still a certain range of cavitation area in this corridor, so it is necessary to adopt another corrosion abatement measure, that is, adding aeration system.The cavitation problem is solved by aeration.Physical model test is the most important method to study aerated flow in the valve corridor of ship lock, but almost no one is involved in the numerical simulation of corridor aeration.Because the aeration conditions of valve lintel are complex and difficult to be simulated, the hydraulic characteristics of aerated flow in the upward and downward expansion corridor behind the valve are numerically simulated in this paper by means of numerical model.Taking the valve corridor of a typical high head shiplock in China as the modeling object, combining the physical model test data and the relevant theoretical knowledge, a new type of sudden expansion geometric model with step drop and rise ridges is established.The VOF model and Mixture multiphase flow model in Fluent software are used to simulate the valve corridor before and after aeration.Finally, the following four main conclusions are drawn:(1) the new type of sudden expansion corridor belongs to the further optimized shape, which increases the pressure in the corridor. Compared with other types of ship lock, the cavitation collapse area of its gallery bottom plate, elevation bar and other parts has been considerably improved.The good corrosion reduction effect is verified by numerical simulation in this paper.(2) when the valve is open at 0.4U 0.5U 0.6 and 0.7, the new type of sudden expansion corridor will produce a certain range of negative pressure areas at the top of the corridor, which will easily produce cavitation; when the valve opens at 0.3 and 0.4 degrees of opening, it will produce a little negative pressure at the first and second steps of the falling ridge.Forming cavitation source;(3) when the valve opening is 0.4 and the aeration rate of the corridor top reaches 18m/s, the negative pressure area of the original corridor top is transformed into positive pressure;(4) the higher the aeration rate, the higher the aeration concentration and the better the negative pressure.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U641.1

【参考文献】