| The radial gate is an important part of the sluice structure in the water conservancy and hydropower project.Its operation condition will has a direct effect not only on the applicability,safety and durability,but also on the safety of the whole water conservancy project.What’s worse,the life and property of the downstream people can also be influenced.During the actual gate operation,dynamic water opening and partial opening are the two basic functions.The radial gate can produce different intensity of vibration when the opening extend is different,which may lead to the dynamic instability of the gate.The vibration source of the gate is the pulsing water pressure happens in the discharge process.The pulsing water pressure possesses randomness with time and space,making the determination of the vibration response difficult.Therefore,it is necessary to test the vibration and analyze the stress of the radial gate.In this study,the radial gate of Daduhe Houziyan hydropower station was taken as the research object,and the on-spot vibration test of the gate was carried out combined with the project acceptance.Then the fluctuating stress and vibration acceleration of the radial gate were obtained under two different water level with different opening degree.The dynamic response parameters such as vibration displacement and related value spectrum characteristics were further obtained by analyzing.The vibration safety of the operation was analyzed and evaluated,the suggestions for the safe operation of the gate were also put forward when it is partially opened.The amplitude of the fluctuating stress and the corresponding dominant frequency of the key components provide the first-hand data for the fatigue life calculation of the gate.The finite volume method hydrodynamic model of reservoir tunnnel chamber gate and water gas was established by a software named FLUENT.The hydrodynamic pressure and its distribution law of the gate panel were obtained according to this under different opening degree.It should be note that stress test values at the key measuring points and the finite element calculation values are in good agreement when taking the hydrodynamic pressure of the panel as load and using ABAQUS software to analyze the stress of the gate structure under different opening.In the analysis of dynamic characteristics,the vibration modes and natural frequencies of the gate under three states in the fully closed and open states were calculated respectively,and the change rules of natural frequencies of each stage under three states were analyzed.The main conclusions are as follows:(1)Through the analysis of the field test and numerical simulation results,it is pointed out that the vibration parameters of the gate structure meet the design and specification requirements,and can ensure the safe operation of the emptying gate.(2)The variation law of vibration amplitude with different opening degree is given.Amplitude of fluctuating stress will reach the largest when the opening of the gate is 5m(full opening),which is the most unfavorable opening degree.Therefore,it is suggested that the time of water discharge should be minimized during the operation of the gate to avoid adverse impact on the gate.(3)The error between the numerical simulation value of FLUENT software and the flow observed in the hydraulic model test is less than 10%,verifying the rationality and effectiveness of the numerical simulation method.The calculation results show that the maximum hydrodynamic pressure of the panel is slightly less than the hydrostatic pressure of the same water head with a full closed gate when the gate is in small opening degree,and the hydrodynamic pressure of the gate face plate is only close to the bottom edge of the gate when the gate is discharged,which decreases sharply from top to bottom.(4)In the analysis of the free vibration characteristics of the radial gate in the fully closed and open water free state,it is found that the low-order vibration mode of the radial gate is mainly the bending and twisting of the arm,which shows that the stiffness of the arm has the greatest influence on the free vibration frequency of the radial gate.The calculated low frequency does not coincide with the main frequency of the high energy pulsation in the water body,which indicates that the possibility of resonance between the gate and the water body is small,and the dynamic performance of the structure meets the needs of the project. |
