Gate Vibration Research Articles

Investigation of the added mass method for seismic design of lock gates

During an earthquake, lock gates are subjected to additional pressure since the water contained in the chamber is put into motion by the earthquake. It is difficult to assess the level of this pressure because the system is affected by a fluid–structure interaction. The gate deformations have an effect on the water pressure, which in turn affects the gate vibrations. A common approach, referred to as the added mass method, consists of simulating the fluid action by distributing lumped masses over the gate. However, this method has been questioned, since the calculation of the lumped masses is usually based on the Westergaard formula, which was derived assuming a perfectly rigid structure. Consequently, fluid–structure interactions may not be captured correctly. This paper proposes to investigate the validity of this approach for such problems and to explain why it might not be conservative. The numerical solutions of an added mass model and a fluid–structure interaction model are confronted. The results indicate that the added mass method may eventually lead to conservative results depending on the type of damping used in the model. Based on these observations, some recommendations are suggested to improve the design of lock gates subjected to earthquakes.

Fluid-Structure Interaction Analysis of Layered Water Intake Structure Considering Load Changes

Coupled vibration of water and stop log gate in the layered water intake structure will occur under the condition of the sudden load changes. A fluid-structure interaction (FSI) finite element model of the layered water intake structure of a hydropower station was established by using the finite element software ADINA to simulate the process of power on and off and the FSI phenomena of stop log gate during each process, and also verify the security of the scheme. The results show that fluid-structure interaction has a significant impact on the running of the layered water intake.

Reducing cross-flow vibrations of underflow gates: Experiments and numerical studies

An experimental study is combined with numerical modelling to investigate new ways to reduce cross-flow vibrations of hydraulic gates with underflow. A rectangular gate section placed in a flume was given freedom to vibrate in the vertical direction. Horizontal slots in the gate bottom enabled leakage flow through the gate to enter the area directly under the gate which is known to play a key role in most excitation mechanisms.For submerged discharge conditions with small gate openings the vertical dynamic support force was measured in the reduced velocity range 1.5<Vr<10.5 for a gate with and without ventilation slots. The leakage flow significantly reduced vibrations. This attenuation was most profound in the high stiffness region at 2<Vr<3.5.Two-dimensional numerical simulations were performed with the Finite Element Method to assess local velocities and pressures for both gate types. A moving mesh covering both solid and fluid domain allowed free gate movement and two-way fluid–structure interactions. Modelling assumptions and observed numerical effects are discussed and quantified. The simulated added mass in still water is shown to be close to experimental values. The spring stiffness and mass factor were varied to achieve similar response frequencies at the same dry natural frequencies as in the experiment. Although it was not possible to reproduce the vibrations dominated by impinging leading edge vortices (ILEV) at relatively low Vr, the simulations at high Vr showed strong vibrations with movement-induced excitation (MIE). For the latter case, the simulated response reduction of the ventilated gate agrees with the experimental results. The numerical modelling results suggest that the leakage flow diminishes pressure fluctuations close to the trailing edge associated with entrainment from the wake into the recirculation zone directly under the gate that most likely cause the growing oscillations of the ordinary rectangular gate.

Experimental Study of Flow-Induced Vibration of Lens-Shaped Vertical Lift Gates

AbstractAn experimental study of two model-scale lens-shaped vertical gates consisting of a truss and plate is presented. Experimental results are applied to the design of the new Nakdong River gates in Busan, South Korea, for flood and irrigation control. Experimental models are developed using finite-element (FE) analysis. A 1:31 scale model is constructed for the short gate (47.5 m wide, 8.5 m high at full scale) using acrylic, and a 1:61 scale model is constructed for the long gate (95 m wide, 8.5 m high at full scale) using an acrylic truss and acrylonitrile butadiene styrene plate. Natural frequencies of the model gates are measured and calibrated with FE predictions. Dynamic characteristics of the flow-induced vibration are compared for two gate orientations. Vibrations of the model gates in Orientation 1 (plate convex in the upstream direction) and Orientation 2 (plate convex in the downstream direction) are measured for various flow conditions. A combination of bottom opening heights and upstream...

Numerical Simulation on Fluid-Solid Coupling of Gate with Different Structure Types of Hemline in Deep Hole

Although there are some achievements of flow-induced vibration of plane steel gate, few is about the influence on gate caused by the difference of structure types of gates hemline. This paper studies on the flow pattern, natural vibration characteristics and dynamic response of four typical types of gates hemline in deep hole of Kajiwa Hydropower Stations service gate. Based on model test and numerical simulation and considering the flow pattern under the gate and in the gate slot, the natural vibration characteristics and the gates dynamic response, it is suggested to use an anteversion angle and a caster angle (type D for short) for the hemline of the type II gate slot. The optimal factors of a gates hemline in a concrete project can be optimized by numerical simulation.

Numerical Simulation on Fluid-Solid Coupling of Gate with Different Structure Types of Hemline in Deep Hole

Although there are some achievements of flow-induced vibration of plane steel gate, few is about the influence on gate caused by the difference of structure types of gates hemline. This paper studies on the flow pattern, natural vibration characteristics and dynamic response of four typical types of gates hemline in deep hole of Kajiwa Hydropower Stations service gate. Based on model test and numerical simulation and considering the flow pattern under the gate and in the gate slot, the natural vibration characteristics and the gates dynamic response, it is suggested to use an anteversion angle and a caster angle (type D for short) for the hemline of the type II gate slot. The optimal factors of a gates hemline in a concrete project can be optimized by numerical simulation.

Free-surface flow simulations for discharge-based operation of hydraulic structure gates

We combine non-hydrostatic flow simulations of the free surface with a discharge model based on elementary gate flow equations for decision support in the operation of hydraulic structure gates. A water level-based gate control used in most of today's general practice does not take into account the fact that gate operation scenarios producing similar total discharged volumes and similar water levels may have different local flow characteristics. Accurate and timely prediction of local flow conditions around hydraulic gates is important for several aspects of structure management: ecology, scour, flow-induced gate vibrations and waterway navigation. The modelling approach is described and tested for a multi-gate sluice structure regulating discharge from a river to the sea. The number of opened gates is varied and the discharge is stabilized with automated control by varying gate openings. The free-surface model was validated for discharge showing a correlation coefficient of 0.994 compared to experimental data. Additionally, we show the analysis of computational fluid dynamics (CFD) results for evaluating bed stability and gate vibrations.

S-Transform Analysis on Pulsating Water Pressure Acting on the Stop Log Gate

The vibration of sluice gate may lead to the damage of the hydraulic structure, based on the S-transform, the frequency and the phase distribution of the pulsating water pressure. The results show that as the water level increases, the frequency of the pulsating water pressure is small, the pulsating power acting on the bottom of the gate is decreasing, the components of frequency are rich, the power is wide, although the amplitude of frequency is decreasing, the whole power of pulsation is not changed; there is an obvious wave about the phase as the time changes, the phase distribution map is symmetry and periodically changes, and the velocity of wave may increase as the frequency increases.

모형실험에 의한 트러스형 리프트 게이트의 진동 특성

본 연구에서는 4대강 사업으로 건설중인 트러스형 리프트의 진동특성을 검토하기 위하여 모형실험이 수행된다. 경간 40 m, 높이 9 m의 트러스형 리프트게이트를 축척 1/25로 모형이론에 따라 아크릴과 납으로 모형을 제작하고, 폭 1.6 m, 길이 25 m, 높이 0.8 m의 수로에서 실험된다. 먼저 모형의 고유진동수가 측정되고 모형을 검증하기 위하여 유한요소 해석결과와 비교된다. 검증된 모형에서 상하류 수위와 문비 개방고에 따른 진동가속도 진폭이 측정된다. 또한 문비의 진동을 줄 일수 있는 하부형상을 검토하기 위하여 문비 최하부의 각도가 <TEX>$20^{\circ}$</TEX>, <TEX>$35^{\circ}$</TEX>, <TEX>$50^{\circ}$</TEX>인 모형을 제작하고 실험결과를 서로 비교한다. 실험 결과는 수문 조작 시 유지관리지침의 기본 자료를 제공하고, 수문의 진동특성과 진동을 줄일 수 있는 수문의 하부형상을 검토한다. A model test is performed to investigate the dynamic behavior of truss type lift gate which is being constructed by the four major rivers project. The gate dimensioned 40 m in width, 9m in height is scaled with the ratio of 1:25 and is made of acryl panel and supplemented weight by lead in the concrete test flume dimensioned 1.2 m in width, 0.5 m in height and 30m in length. Firstly natural frequencies of the model gate are measured and compared with the numerical results for the calibration. The amplitudes of the vibration are measured under the different gate opening, upstream water level conditions. Also models with bottom angle <TEX>$20^{\circ}$</TEX>, <TEX>$35^{\circ}$</TEX> and <TEX>$50^{\circ}$</TEX> are tested and compared to find out a proper shape of bottom structure which minimizes the gate vibration. These test results presents a basic data for the guide manuals of gate management and a design method to reduce the gate vibration of truss type lift gate.

Study of Flow-Induced Vibration for the High-Head and Large Dimension Gate

In this paper study findings of flow-induced vibration of gate in the emptying culvert of Tishengqiao power station are presented. At first stage structure’s dynamic characteristics are investigated carefully using the experimental modal analysis technique, and entire structure modal information is obtained. In addition, flow pulsating pressure properties acting on the gate are investigated. Various physical values including vibration acceleration, dynamic displacement and dynamic stress caused by high velocity flow are studied. Finally gate structure’s dynamic reliability is analyzed and safety operation principle are presented.

351 2種類のモデルを用いたテンタゲートの並進型自励振動に関する実験(振動・超音波I,学術講演)

351 2種類のモデルを用いたテンタゲートの並進型自励振動に関する実験(振動・超音波I,学術講演)

Study on Flow-Induced Vibration Characteristics of Hydraulic Hoist of Large-Span Upwelling Radial Steel Gate

In this paper we conduct study on flow-induced vibration of large-span upwelling radial steel Gate and its hydraulic hoist. Place an emphasis on vibration response characteristics under two working conditions of diversion and drainage, which proves the safety of hydraulic hoist gate vibration caused by gate vibration. Firstly, we study on dynamic characteristics of fluid-structure interaction of association system of gate and start and stop lever, reveals the discipline of the effect fluid having on structural dynamic characteristics. On this basis, flow-induced vibration characteristics under two conditions of with and without start and stop lever action considered. The results indicate that the gate vibration response with hydraulic hoist used decreases, which explains start and stop lever has certain effect of restraining vibration on gate vibration. In addition, under the working condition of drainage the vibration magnitude of start and stop lever is smaller than that of gate body, which explains there is damping action during transference of gate vibration through start and stop lever. The results find out that on the assumption of optimized gate structure and hydraulic arrangement, it is practicable, safe and reliable to adopt hydraulic hoist. The achievement has directive significance on similar projects construction in the future

트러스형 리프트 게이트의 진동현상에 관한 모형실험

A model test is carried out to investigate the vibration of truss type lift gate in the four major rivers project. The gate model scaled with the ratio of 1 : 25 is made of acryl panel dimensioned 1.6 m in width, 0.28 m in height in the concrete test flume. Firstly natural frequencies of the model gate are measured and the results are compared with the numerical results in order to verify the model. The amplitudes of the vibration are measured under the different gate opening and water level conditions. The results are analyzed to study the characteristics of the gate vibration according to the small gate opening, the large gate opening and the overflow conditions. These test results presents a basic data for the guide manuals of gate management and a design method to reduce the gate vibration of truss type lift gate. Finally, the vibration of truss type lift gate are assessed in comparison with those of formerly tainter gate.

Monitoring Technique and System of Hydraulic Vibration of Sluice Gate in Long Distance Water Conservancy Project

Hydraulic vibration due to turbulent flow at large-scale sluice gates used widely is of a serious threat to water security of long distance water conservancy projects. It is one of important technical measures to monitor and analyze on-line vibration of hydraulic gate for the safety of hydraulic engineering. A hydraulic vibration monitoring system of gate structure is proposed in which the accelerometers specially designed for long-term operating in deep poor water and complex flow are used. It is proved by test and application that the accelerometer has good waterproof, pressure resistance, anti-erosion resistance, high temperature changes and so on. The system meets the requirements of harsh deep water environment and is of long-term safe and reliable.

Analysis on Flow-Induced Vibration of Underwater Horizontal Gate

The best is to read these instructions and follow the outline of this text. The physical and numerical models were combined to analyze flow-induced vibration response of Qingshuihe River underwater horizontal gate in this paper; the pressures acting on the gate were divided into two parts: the fluctuating pressure of flow on the stationary gate and the hydrodynamic pressure caused by the gate vibration, which is additional pressure induced by disturbed flow. The temporal-spatial correlation of fluctuating pressures obtained by model experiments between different nodes was analyzed. In the study the coherence function is defined in frequency domain with consideration of different levels of correlation for different frequency components, and the nodal load of the fluctuating pressure could be obtained. A new distribution of additional mass with considering radial vibration of the gate is adopted as equivalent hydrodynamic pressure. Based on random vibration theory, the flow-induced vibration response of the gate was obtained. The results provide the reliable reference evidence for structural dynamic design of the gate and show that the hydrodynamic stability of the gate can meet the requirement. On the other hand, it is shown that this method is reasonable and feasible.

820 大形テンタゲートの複合発散振動に関する3次元モデル実験 : ゲート全体のトラニオンピン周りの振動に同期した場合

This paper presents the test results of coupled-mode self-excited vibration of Folsom dam Tainter-gate by the large-scaled 3-dimension model gate. The Folsom gate was represented by a 1/31-scaled model, where the whole gate vibrates around the trunnion pin and the skinplate vibrates in the streamwise direction. Both the vibration modes will couple through hydrodynamic and inertial forces. This type of coupled-mode vibration is accompanied by the flow-rate variation under the gate, thus inducing a violent self-excited vibration in certain conditions. In the present model tests, the frequency ratio of the skinplate streamwise in-water natural vibration to the whole gate rotational vibration around the trunnion pin was varied from 0.8 to 1.5. As a result, the vibration synchronized with the whole gate vibration around the trunnion pin was revealed, in addition to the vibration synchronized with the skinplate streamwise vibration.

3717 テンタゲートにおける変動流量係数とその開度依存性(J13-3 流動励起振動3(直交流れによる振動等),J13 流体関連の騒音と振動)

The flow-induced coupled-mode self-excited vibration of huge Tainter gates were theoretically analyzed, and it was confirmed the validity by the model experiments. However, the experimental results have suggested that the instantaneous flow-rate coefficient does not correspond to 1:1 to vibration of a gate. Therefore, in order to clarify the characteristic of the instantaneous discharge flow from the gate bottom, we had many experiments. However, there was a problem on measurement accuracy in response to the influence of the contraction flow. This paper present the test results for variations in flow rate from the gate bottom. The instantaneous discharge velocity caused by the gate vibration was measured at the down-stream rather than the gate bottom, by LDV. The characteristics of instantaneous discharge flow were examined in detail, and the dependability of gate opening was also examined.

Properties of single shear layer instabilities and vortex-induced excitation mechanisms of thick plates

The basic findings of an experimental investigation of flow-induced vibrations of gate plates with multiple degrees of freedom are presented. The study focused on the fluid dynamic behaviour of the single shear layer separating from a thick rectangular plate. The principal aim of the study was to further the physical understanding of instability-induced excitation mechanisms (IIE) involving shear layer instabilities and vortex generation. It is shown that this type of gate vibration is caused by two dominant excitation mechanisms: cross-flow and streamwise impinging-leading-edge-vortex (ILEV) excitation and streamwise body-resonant leading-edge-vortex-shedding (BR-LEVS) excitation. The first mechanism is caused by the local interaction of the shear layer underneath the gate plate with the trailing edge of the gate lip. The second mechanism is produced by the instability of the shear layer in the tailwater of the gate, with the instability being necessarily triggered by the elastic motion of the flow separation at the leading edge of the gate.

627 フォルソンダム・テンタゲートの大開度放水時における複合発散振動に関するモデル実験

This paper presents the model test results of coupled-mode self-excited vibration of Folsom dam Tainter-gate at its large openings. The Folsom gate was represented by a 1/31-scaled model, where the whole gate vibrates around the trunnion pin and the skinplate vibrates in the streamwise direction. Both the vibration modes couple well through hydrodynamic and inertial forces. This type of coupled-mode vibration is accompanied by the flow-rate variation under the gate, and under certain conditions a violent self-excited vibration is induced. In the present model tests, the Froude number was fixed at 6.67, the reduced gate opening height relative to the gate submergence depth was adjusted up to 11.9%, and the whole gate vibration frequency was varied. As a result, it was concluded that the gate dynamic instability decreases in its intensity, with increasing the gate opening, and the fluid excitation effect disappears at the reduced gate opening of about 14%.

721 下端放水を行うシェル形長径間ゲートの流体関連振動に関する研究 : 自励振動特性に及ぼす傾斜面の水平距離の影響

This paper presents effects of the horizontal length of the weir plate for flow-induced vibration of shell-type long-span gates with small underflow. Experimental results for flow-induced vibration of 5 model gates, which have different length of the weir plate, were shown first and the instability for each gate was described secondly. Furthermore the relationship between the instability and gate motion trajectory derived using experimental results for the hydrodynamic force acting on their inclined weir plate were discussed.