Study On Hydraulic Simulation And Control Of The Complex Water Diversion System

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.