Study On The Hydraulic And Climbing Vibration Characteristics Of Hydrodynamic Closing Of Emergency Gate In The Discharge Tunnel

The hydrodynamic characteristics of the emergency gate inside the tunnel in the process of closing are very complicated,its flow regime of the gate area changes from full-flow to open-flow.And the adverse flow conditions,improper design of the bottom edge or irrational support structure will affect the normal operation of the gate,cause violent vibration of the door,even with a large amplitude of climbing phenomenon,which will make hit shock load of the crane,adverse to the opening and closing device and gate operation.Previous research on the hydraulic characteristics of closed-door process were mostly experimental,and the numerical simulation work was less;Furthermore,the targeted research report to explore the climbing vibration phenomenon was rare,and related regularity was even not involved.Therefore,this paper relies on the Maredang emergency gate,combine with the physical model test and numerical simulation method to study the hydraulic characteristics of the gate,analysis the influence of the bottom edge type on the holding force and the cavitation characteristics of the gate bottom;In addition,taking the water conservancy hub prototype observation results as the research of the introduction,using the pulsating characteristics of closed-door holding force to measure the gate vibration,and through experiment to explore the influence factors of gate vibration climb in the Maerdang physical model,then propose measures for vibration reduction.The main results are as follows:(1)According to the physical model of the Maerdang hydraulic model test results,combined with the EMD trend term extraction method,comprehensive study on the flow pattern,pulsation pressure and the holding force during the closing process,then analysis of the impact of operating conditions on the hydraulic characteristics,therefore provide a reference for the numerical simulation of the hydrodynamic closure.(2)Using RNG model and the VOF method,combined with the dynamic mesh technique,the numerical simulation of the plate gate closing process with different bottom edge types was carried out.Result shows:the bottom pressure of front bottom type and combined bottom type is uplift,which will increase the holding force;while the bottom pressure form of flat bottom type and Rear bottom type are related to the flow pattern.full-flow tends to uplift,otherwise open-flow tends to suction,and the increase of the downstream angle will reduce the suction force,thereby reducing the holding force.In addition,the analysis of the cavitation characteristics of the gate bottom,found that after the Rear bottom type(mainly in the second half bottom),flat bottom type are the most prone to cavitation damage.(3)Based on the original floor vibration test of a water control project,it is found that the phenomenon of large climbing vibration occurs during the process of closing the gate.Therefore,based on the physical model test device of the Maerdang,the relevant factors affecting the climbing vibration are explored.Result shows:the friction coefficient is one of the main factors that affect the vibration of the gate,and the material of the sliding block can also change the vibration characteristics.From the point of view to benefit the door drop,measures like reduce the support friction coefficient and the upstream water level or the opening of working gate,increase the gate weight and others can be used.Consideration from the reduction of gate vibration climb,reduce support friction coefficient and the opening of working gate,the opening and closing speed,or increase the weight and diameter of the slider gate can effectively improve or inhibit gate vibration climb.