Experimental Research And Numerical Simulation On Vibration Characteristic Of Hydraulic Automatic Rolling Gate

With development of industry and agriculture, water resources contradictionbetween supply and demand is increasingly prominent in the North areas of China, inwhich short of water resources. However it is true that the existing water resources can notbe used reasonably. For example, there are a series of problem in the process of utilizingsediment-laden and high silt concentration flood resources. With study on the new typehydro-automatic roller gate which can be open and close automatically under sedimentdeposition situation, it is possible to utilize such flood resources effectively. A series ofhydraulic-model experiments approved the assumption about new type hydro-automaticroller gate in this paper feasible. Such gate could work automatically under the waterpressure while silting in front of the gate. In order to design the hydro-automatic roller gatecorrectly, it is important to study the strength, stiffness and stability of the hydro-automaticroller gate which is subjected to the hydrodynamic pressure accurately. It is easy to solvethe problems about the strength, stiffness and stability of the hydro-automatic roller gatewhich is under hydrostatic pressure before the gate is opening. However after the gateopening, the related calculation method about the gate under the hydrodynamic pressure isnot available, especially the calculation and design method about vibration anddeformation of Automatic Rolling Gate. In this thesis the distribution Law of deformationand vibration of cylinder gate under the hydrodynamic pressure, which is transverselyplaced in the water flow, are studied with methods of model experiments, numericalstimulation and theory analysis.Main research contents are as follows:(1)Through hydraulic-model experiments, variation law of vibration acceleration, vibrationamplitude and vibration frequency under the hydrodynamic pressure for the eachcharacteristic points on the cylinder gate surface are discussed under different upper leveland jaw opening situations.(2) Mathematical modeling is built on the base of physical model. So the hydrauliccharacteristic of the cylinder gate that is transversely placed in the water flow is analysis by the numerical simulation method. The hydrodynamic pressure are placed on thecylinder gate surface by the numerical simulation method to determinate the distribution ofstress and strain, and variation law of deformation on it. The distribution situation ofvibration amplitude of the cylinder gate that is transversely placed in the water flow isresearched, so that the safety operation of the Hydraulic Automatic Rolling Gate is ensuredin the future.(3)A modal analysis to the cylindrical shell is carried out by applying numericalstimulation method to fix vibration frequency and distribution mode of vibration of thecylindrical shell immerged under water. It will provide reasonable foundation for theHydraulic Automatic Rolling Gate design in the future.The main results from hydraulic-model experiments and numerical simulation are asfollows:(1) The distribution trend of vibration acceleration along the upstream face of theHydraulic Automatic Rolling Gate is increasing first, then reducing, and increasing againfrom top to the bottom of the gate under the hydrodynamic pressure. The value of vibrationacceleration reaches minimum atφ＝135°, below centre line of the cylindrical tank.Whereas the related value atφ＝45°andφ＝180°is comparatively larger(2) When jaw opening, h under the cylindrical tank is invariable, vibration displacementamplitude on the Rolling Gate is increasing gradually with Upstream depth, H is rising.The value of vibration displacement of the Rolling Gate reaches the maximum whileupstream depth is near the top of the Rolling Gate. But when the upstream water levelkeeps raising, the value will be decreasing.(3) When upstream depth, H is a constant, whereas jaw opening, h is a variable, and theupstream depth is over the top of cylindrical tank, vibration amplitude of the Rolling Gateshows an enhanced trend with jaw opening, h under the cylindrical tank increasing. Ifwater level is below the top of cylindrical tank, the Rolling Gate vibration presents reducedtrend with jaw opening, h under the cylindrical tank increasing.(4) Through the analysis result of the acceleration spectrum, it can be manifested thatvibration of the cylindrical tank is the low frequency vibration, which is far from the basicpulsation pressure frequency, about f=50Hz. That illustrates that structure design of thecylindrical tank is safe and reasonable.(5) Compared analysis result of bidirectional fluid-solid coupling with that ofunidirectional fluid-solid coupling, it is found that the result is tally with the actualsituation more. So analysis method of bidirectional fluid-solid coupling is applied in this thesis.(6) From the result of the simulation, it is demonstrated that the max displacement of thecylindrical tank is on its top where along the flow direction under the effect ofhydrodynamic pressure. Moreover hinged joint at the bottom of the Rolling Gate should bepaid more attentions, because stress and strain in the hinged joint is max.(7) It is testified that the change trend basically tallies by the comparison betweensimulation result and experiment result. Vibration displacement of the cylindrical tankreaches maximum on the top of tank near water surface profile.(8) The related mathematical modeling is set up to analysis modal of the cylindrical tank inthe water. Finally it will provide a solid foundation for reasonable design of the hydraulicautomatic rolling gate.