【作者】 穆祥鹏；

【导师】 练继建；

【作者基本信息】 天津大学 ， 水利水电工程， 2008， 博士

【摘要】 修建大型长距离输水工程是调节水资源时空分布不均,解决水资源供需矛盾的最有效、最直接的手段。输水系统在发生水力过渡过程时系统沿线的水力要素随时间发生急剧的变化,如不在设计与运行时加以控制,往往会超出恒定流的设计范围,对输水过程造成不利影响。因此,在设计和运行管理阶段都必须对水力过渡问题给予足够的重视,才能确保工程的安全与可靠。对输水系统在各种工况下的水力仿真和控制进行系统全面的分析和研究势在必行。本文以复杂的输水系统为研究对象,通过输水系统整体数值模拟与局部模型试验相结合,针对引发输水系统过渡过程的流量调节、泵站事故、检修、不对称输水以及管道充水等各种工况,构建相应的数学模型,在对各种不同的水力过渡过程进行模拟仿真的基础上,研究复杂输水系统在不同工况下的非恒定流水力特性,并从工程设计和运行角度提出针对相应非恒定流工况的水力设计与控制原则,本文的主要结论可以概括成如下几个方面:(1)针对代表复杂输水系统水力过渡过程的无压流、有压流、无压接有压、明满流交替等不同非恒定流过程,对特征线法和隐式差分法进行对比,研究和确定了两种方法在不同输水方式和水流状态下的适用性。通过采用自由气体-液体离散模型和变波速模型对气液二相瞬变流的模拟,对气液二相流的水力特性进行了分析和研究,并对自由气体-液体离散模型和变波速模型的适用性进行了研究。(2)根据不同流态,通过物理模型试验对保水堰的流量系数、局部损失系数、淹没系数等特性参数进行了测量和分析,并对保水堰的流量系数、淹没系数对水力仿真的敏感性进行了分析。利用模型试验数据对巴甫洛夫斯基的堰流淹没系数数据进行了补充,并构造了保水堰淹没系数关于淹没度的函数曲线,对保水堰的边界提出了动态淹没系数的改进方法,可以很好的模拟保水堰的各种流态变化,为保水堰过渡流态的准确模拟提供了一种可供借鉴的方法。(3)分别建立了无压接多孔并联分段低压输水系统的流量调节、事故停泵、单孔检修的水力仿真模型,预测过渡过程中输水系统的压力、水位、流速和流量等水力参数的变化规律,对分段低压输水结构的水力特性进行分析,寻找可靠合理的输水运行控制方案。提出了复杂输水系统的流量调节及事故停泵的水力控制原则。针对长距离并联输水箱涵的检修操作,提出了一种补水的控制方法,通过在检修箱涵的首尾设置补水孔,利用非检修箱涵向检修箱涵补水,对长距离并联输水箱涵单孔检修所造成的闸后检修箱涵脱空进行了有效控制,该控制方法对于长距离有压输水系统具有一定的推广应用价值,对于长距离并联输水箱涵连续关闸和变孔数运行等运行操作的水力控制也有一定的借鉴意义。(4)建立了多孔并联的无压接有压的输水系统的不对称输水仿真模型,对于无压段的不对称输水对下游有压管段的影响进行了分析,针对于有压段的不对称输水问题,为连续关闸和连续开闸的操作确定了最佳的闸门操作序列,并将补水的方法成功应用于连续关闸的过渡过程控制,最后提出了长距离输水系统不对称输水的控制原则。(5)将虚拟流量法与隐式差分法相结合构建了有压管道充水操作的数学模型,实现了对有压管道充水过程的准确模拟,对有压管道在充水过程中的水力特性进行了分析和研究,并在水力仿真的基础上提出了变流量充水的控制方法,既保证了充水过程中输水管道的安全,又缩短了管道的充水时间。(6)针对水力控制中出现的具体问题,对分段低压输水系统各输水单元的具体建筑物指标和参数反映出的单元之间的相互联系进行分析和研究,最后在水力控制的基础上提出了分段低压输水系统的整体优化设计原则,此优化原则可以作为分段低压输水系统的设计依据,有较大的推广应用价值。更多还原

【Abstract】 The long-distance water diversion project is the most effective and direct countermeasure to the supply-demand contradiction of water resource. The flow and hydraulic pressure of the water diversion system is unstable and maybe overstep the design scope in hydraulic transient, which will be critical with the safety of the project. For ensuring the security of the project, much importance must be attached to the hydraulic transient. So the analysis and study on hydraulic simulation and control to the hydraulic transient of water diversion system under various work conditions must be developed.In this paper, the complex water diversion system is the study object. According to the flow regulation, pumping station accident, inspection, asymmetric water diversion and Water-filling in pressure conduits, the mathematic models are established to simulate the hydraulic transient. The hydraulic characteristics of unsteady flow are researched under various work conditions and the optimization control principles and project design schemes are proposed from the view of project design and operation. Some achievement of the thesis is listed below:1. Comparison between characteristic line method and implicit difference method is based on the solution to the transient of free flow, pressure flow, free flow connected with pressure flow and free-pressure flow of water diversion system. Then the characteristics of the two methods are analyzed and the applicability of the two methods to various water diversion modes and transient types is studied and ascertained. The discrete gas-liquid model and the variable wave speed model are used to simulate the gas-liquid two-phase transient flow. The hydraulic characteristics of two-phase transient flow are analyzed and the applicability of the two models to two-phase transient flow is researched.2. According to the various flow pattern of water conservation weir, the flow coefficient, the local head loss coefficient and submerging coefficient are measured and analyzed through the physical model tests. Then the sensitivities of the flow coefficient and submerging coefficient are analyzed. In order to make the exact simulation of the transition flow pattern of water conservation weir, a new method of dynamic submerge coefficient of water conservation weir is brought forward by using curvilinear equations based on model test data andПавловский’s data. Then it is proved that the method of dynamic submerge coefficient of water conservation weir is applied and universal to simulate the transition flow pattern of water conservation weir.3. The numerical models of open channel and multiple-hole stepped low-pressurized water diversion system are established to simulate the unsteady flow results from flow regulation and pumping station accident and to forecast the pressure, the water level, the flow and the current velocity in the transition. The hydraulic characteristics of stepped low-pressurized water diversion system are analyzed and the hydraulic control principle is proposed for flow regulation and pumping station accident of complex water diversion system. According to the inspection of multiple-hole water diversion culverts, a water replenishing method is brought forward to control the water hammer. Water replenishing holes are set at the head-tail end of water diversion culverts and adjacent culverts replenish water to inspection culvert to control and slow up the transient that result from the inspection. At last the sizes of the water replenishing holes and the inspection well are optimized based on hydraulic control. This water replenishing method has great applied value to hydraulic control of the inspection and has reference meaning to hydraulic control of continuous sluice shut of long-distance pressure water diversion system.4. The numerical models of open channel and multiple-hole stepped low-pressurized water diversion system are established to simulate the unsteady flow results from asymmetric water delivery. The influence of asymmetric water delivery in open channel on transient in pressure pipeline downstream is analyzed. According to the asymmetric water delivery in pressure pipeline, optimal sequences of continuous shut and open to inspection gates are proposed and water replenishing method is applied to hydraulic control on continuous sluices shut successfully. At last the hydraulic control principle is brought forward for asymmetric water delivery of long-distance water diversion system.5. Based on fictitious flow method and implicit difference method, the numerical model of water-filling in pressure conduits is established to simulate the water-filling process well and truly. Based on the hydraulic simulation, the hydraulic characteristics of the water-filling process are researched and the method of variable flow water-filling is proposed which can ensure the security of pipeline and shorten time of water-filling process.6. According to practical problems in hydraulic control, the correlations among the water delivery units are analyzed and researched that are reflected by structure parameters of the water delivery units of stepped low-pressurized water diversion system. Based on hydraulic control and analysis, the principia of optimization to the stepped low-pressurized water diversion system is proposed, which can be used as design basis of stepped low-pressurized water diversion system and have great application value.更多还原