Vibration Test And Numerical Simulation Of Steel Scluie Gate In Deep Hole Spillway Tunnel Of Houziyan Hydropower Station

Hydraulic steel gate play a role in controlling the flow in the discharge of th e reservoir.When the gate is opened,the direct action of water flow pulsation and the interaction of fluidstructure coupling will cause the gate to vibrate.When the gate is operated at different water levels and different openings,the degree of vibration is also different.In some cases,it will threaten the safety of the gate and even further affect the safety of the dam.The water conservancy and hydropower engineering community is very concerned about this.The vibration source causing the gate vibration has random factors,the mechanism is very complicated,and the resulting vibration response is difficult to calculate.It is necessary to carry out on-site testing and related research on gate vibration.Combined with the completion acceptance of the large-scale hydropower project-Houziyan Hydropower Station,On-site testing and analysis of flow-induced vibration during the discharge process of the radial steel gate of the deep-hole spillway tunnel under different openings at the water levels of the two reservoirs.FLUENT was used to establish a finite volume method hydraulics model of reservoir-hole-gate and water body,the dynamic water pressure on the gate panel under different water level and different opening degree was calculated,and the distribution law of dynamic water pressure was summarized.Furthermore,the three-dimensional finite element model of the gate was established using ABAQUS,and its dynamic characteristics and stress under different operating conditions were calculated and analyzed.Judging and evaluating the vibration strength of the gate and the existence of resonance conditions based on field test results,and making recommendations for the safe operation of the gate.The pulsating stress amplitude and dominant frequency of the key components obtained from the field test analysis data provide first-hand information for further fatigue life assessment of the gate.Accumulated experience data for subsequent similar engineering design.The main conclusions of this article are as follows:1.Field test and numerical simulation results show that under each working condition the stress value of the steel gate is less than the material design stress,which meets the strength safety requirements,and the important members such as the main beam have sufficient strength and safety.2.Field test results show that the pulsating stress and vibration acceleration are relatively large when the gate opening stays near 6.75 m in the process of draining.According to the calculation results of dynamic displacement combined with foreign vibration standards,it is determined that 95%of the vibration displacement of the radial steel gate of the deep hole spillway tunnel under the two water levels belongs to small vibration,and the gate operation is in safe operation.It is recommended that the gate should not stay too much near the opening of 6.75 m(relative opening 75%)when the water is discharged.3.Vibration acceleration power spectrum analysis shows that the dominant frequency range of the gate vibration during the discharge process is concentrated within the range of 10～20 Hz.During the discharge process,the gate vibration avoids the main frequency area of the water flow shock.The gate can be opened at various openings safe operation.4.When the gate is fully closed when there is no water and the gate is constrained by the pier,the first eight orders of natural vibration frequency are in the range of 18.8 Hz to 41.5 Hz,which is much higher than the oscillating frequency of the water flow.In the free vibration state of the door leaf during lifting,the natural vibration frequency drops to 4.26 Hz,and the gate may have resonance.5.Under different working conditions,the stress calculated by the test and numerical simulation is consistent with the change of the opening degree,and gradually decreases as the opening of the gate increases.The stress measured by the test point at each opening of the gate is generally greater than the stress obtained by numerical simulation.