Gate Vibration Research Articles

Method and Application of Spillway Radial Gate Vibration Signal Denoising on Multiverse Optimization Algorithm-Optimized Variational Mode Decomposition Combined with Wavelet Threshold Denoising

To address the noise issue in the measured vibration signals of spillway radial gate discharge, this paper utilizes the Multiverse Optimization Algorithm (MVO) to optimize the number of decomposition modes (K) and the penalty factor (α) in Variational Mode Decomposition (VMD). This approach ensures improved efficiency of VMD decomposition while maintaining accuracy. Subsequently, the obtained Intrinsic Mode Functions (IMFs) from VMD decomposition are classified based on Multi-scale Permutation Entropy (MPE). IMFs are divided into pure components and noisy components; the noisy components are processed with Wavelet Threshold Denoising (WTD), while the pure components are overlaid and reconstructed to obtain the denoised vibration signal of the gate. Comprehensive comparisons involving artificial signal simulations, gate flow-induced vibration model tests, and numerical simulations lead to the following conclusions: compared to other algorithms, the proposed combined denoising method (MVO-VMD-MPE-WTD) achieves the highest signal-to-noise ratio (SNR) in both the frequency and time domains for artificial signals, while yielding the lowest mean square error (MSE). In the gate flow-induced vibration model tests, the method significantly reduces noise in the vibration signals and effectively preserves characteristic information. The error in preserving characteristic information across model tests and numerical simulations is kept below 1%. Furthermore, compared to other optimization algorithms, the MVO demonstrates higher computational efficiency. The parameter-optimized combined denoising method proposed in this study provides insights into denoising measured vibration signals of hydraulic spillway radial gates and other drainage structures, and it opens possibilities for exploring more efficient optimization algorithms for achieving online monitoring in the future.

Research on the influence of rigid body modes on the operating vibration of arc gate

Abstract The 5# arc working gate of Jiangshan Wanyao Reservoir is composed of the suspension system of the gate and the steel wire rope, which has a serious vibration phenomenon when running without water. Firstly, the rigid body modal analysis of the gate suspension system is analyzed, the position size of key components such as gate support hinge shaft, gate motion guide embedded parts, and main beam position state is measured and evaluated on site, and the dynamic stress and vibration of the support arm are tested and analyzed during gate operation. It is concluded that the influence rule and weight of the steel wire rope on the rigid body mode of the gate, the torsional position of the gate, and the uneven operation condition of the side guide lead to the rigid body mode of the gate. It is suggested to improve the twisting state of the gate, adjust the unevenness of the embedded parts, and weaken the factors that induce the modal vibration of the rigid body.

Experimental Study on the Slip–Stick Vibration of Plane Gate

The slip–stick vibration intensity of a plane gate is usually large, which often brings serious safety risks to itself and the auxiliary structure. The slip–stick vibration of a plane gate is investigated using an experimental model test. The test conditions mainly focus on the gate-closing and gate-opening processes in transient flow. Based on the results, comparison diagrams of the slip–stick vibration response versus the external fluid excitation are constructed. The intensity and period of the slip–stick vibration both gradually increase with the opening degree of the plane gate decreasing. The frequency of slip–stick vibration is consistent with the natural frequency of the equivalent system, indicating that the slip–stick vibration is a nonlinear self-excited vibration. The slip–stick vibration and fluid excitation acting on the plane gate have a significant difference in response intensity and dominant frequency. In addition, a difference in gate support material can have a significant effect on the slip–stick vibration intensity. Therefore, the friction factor between gate support and track, rather than the fluid excitation, is the direct cause of slip–stick vibration, which can further prove that the slip–stick vibration is a friction-induced vibration caused by the gate’s active motion, enriching the theory of the gate’s vibration.

Numerical Simulation and Application of Radial Steel Gate Structure Based on Building Information Modeling under Different Opening Degrees

The safe and stable operation of the radial gate is highly essential for hydropower stations. As the dynamic load of gate, water flow generally causes the irregular distribution of strength, stiffness, and the stability of the gate structure. Traditional simulation technology is usually used to investigate the impact of water flow on gate structure; however, there is a lack of integration and interaction of building information modeling (BIM) and numerical simulation technology to study this issue. Therefore, this paper proposed a computational framework combing BIM and numerical simulation to calculate and analyze the large complex hydraulic radial steel structure. Firstly, the 3D model of the radial gate was established by MicroStation2020, then, the finite element model was output by using it. Secondly, the change laws of strength, stiffness, and stability of the radial gate were analyzed by Ansys-Workbench2020R2 under different opening degrees. The numerical simulation results show that the maximum equivalent stress value was 142.19 MPa, which occurred at the joint between the lower longitudinal beam and the door blade. The maximum deformation was 3.446 mm, which occurred at two longitudinal beams’ middle in the lower part of the panel. When the opening degree is 0.0 m–9.0 m, the natural vibration frequency increases irregularly with the increase in the opening of the gate. Three main vibration modes of the gate vibration were obtained. It proves that it is feasible to analyze the structural performance of radial gates by using BIM and numerical simulation. Finally, the BIM and numerical simulation information management process was established to make the simulation results more valuable. This study expands the application value of BIM and provides a new research idea for large complex hydraulic steel structural analysis. The information management process described in this research can serve as a guide for gate operation and maintenance management.

Chaotic Characteristic Analysis of Spillway Radial Gate Vibration under Discharge Excitation

This paper aims to assess the nonlinear vibration of a radial gate induced by flood discharge; the measured acceleration response data of a spillway radial gate are analyzed using the chaos theory. The results show that the vibration responses of the gate at three opening heights present clear chaotic characteristics, and the chaotic characteristics of the lower main beam point are greater than other points. Moreover, the y-direction (vertical) correlation dimensions of the three measuring points on the supporting arm are larger than those of the x-direction (axial) and z-direction (lateral). The vertical vibration of the supporting arm is more complex and presents more uncertainties, which should be paid attention to in the literature. Under three different gate opening heights, the maximum Lyapunov exponent of each measuring point ranges from 0.0246 to 0.0681. In addition, the flow fluctuation load is the main excitation source of the gate vibration chaotic characteristics.

Characteristics of air flow driven by the water free surface in a free-flow spillway tunnel

Air is transported downstream by the water flow in a free-flow spillway tunnel, resulting in high negative pressure, which causes gate vibration and cavitation. In this research work, a physical model of a free-flow spillway tunnel was used to investigate the effects of water surface velocity and the area residual of tunnel cross sections on air movements. The results demonstrate that the air velocity distribution forms an S-shaped curve. As the water surface velocity increases or the area residual decreases, the air velocity increases, and the relative action height of the drag force of water flow on the air increases as well. The air velocity distribution is divided into two exponential distributions at the position where the air velocity drops by 0.2 times that of the water surface velocity. Two formulas for calculating the air velocity of the corresponding exponential distributions are developed. Subsequently, an algorithm for the air demand is presented, and the relative error compared to the reference data was less than ±20%. These results provide a reference for free-flow spillway tunnel ventilation shaft design.

Numerical Analysis of Flow-Induced Vibration of Deep-Hole Plane Steel Gate in Partial Opening Operation

Hydraulic steel gates are the core adjustment mechanism for water conservancy projects, the safety of which is related to the safety of the entire water conservancy project. In this study, the issue of flow-induced vibration under the influence of pulsing water pressure when the deep-hole plane steel gate construction is partially opened is investigated using a numerical calculation approach of CFD–CSD coupling. The time-history pulsating pressure loads of each part are first determined by tracking the upstream, bottom, and downstream pulsating water pressure loads under partially open operation conditions of the gate. The impact of the water in front of the gate on the natural vibration mode and frequency of the gate is then investigated based on the analysis of the dry/wet modes of the gate structure. Additionally, the hydrodynamic load is applied to the finite element model of the gate structure while taking into account the fluid–structure coupling effect, and the results of the gate flow-induced vibration response are obtained. Three typical local opening relative openings are chosen, with the operating state of the design water head (Hs = 70 m) of a deep-hole plane steel gate as an example. According to the analysis’s findings, the gate’s natural vibration frequency is greatly lowered under the influence of the water in front of it, and its amplitude increases by 50%. The pressure value pressing on the gate changes dynamically as it is partially opened and discharged. The maximum dynamic displacement value and the maximum dynamic stress value of the gate both appear in the middle and lower part of the gate under the condition of partial opening, and both occur when the relative opening is e/H = 0.125. The maximum displacement value is 3.43 mm, and the maximum stress value is 161 MPa. The maximum dynamic displacement and dynamic stress of each gate component steadily decrease with an increase in the relative openness. The gate dynamic response analysis approach described in this research can serve as a guide for hydraulic engineering design.

Koraci u rekonstrukciji za poboljšanje perfrormansi rada zatvarača na temeljnom ispustu

Dams and Hydropower plants in the Balkan region, especially in the countries of Ex-Yugoslavia, are coming to a period were reconstruction works have to be considered, to prolong their operational period and to improve their performance. The following paper represents a sublimate of series of steps taken for reconstruction and performance improvement of a Dam Bottom Outlet Regulation Gate. As the standards back in those days were slightly different from todays, and the equipment manufacture was also different, the main challenge was to take certain steps, such as analytical calculation approach, numerical CFD and FEA simulations and also mechanical reconstruction works, to make scope of workflows on the hydraulic gate, to improve operational range, reduce lifting loads and improve gate vibrations. Numerical simulations of the outflow conditions of the bottom outlet were carried out, and later were proved with drone footage to observe the outflow pattern. Besides, full dry and wet test measurements were made before and after reconstruction works, where significant performance improvement of the gate operation was achieved.

Holding Force and Vertical Vibration of Emergency Gate in the Closing Process: Physical and Numerical Modelling

A two-dimensional unsteady fluid–structure interaction numerical model was established, based on the physical model test, to investigate the influence of vertical vibration on the holding force of an emergency gate in the closing process. Gate motion was controlled by the user-defined function in Fluent. Attention was paid to the relationship between the vertical vibration, hydrodynamic loads and flow discharge. The experiment results show that holding force has three typical forms in the closing process and it is related to the service gate height. The numerical model can reflect the gate vertical vibration and the gate-closing displacement in the form of steps. Gate vertical vibration in the closing process is a motion-induced vibration caused by gate active falling. Moreover, the transition from full-flow to open-flow behind the emergency gate has a great influence on the gate vertical vibration. With a small gate opening, gate vertical vibration makes the flow discharge fluctuation increase. Furthermore, flow discharge has an influence on the gate body loads, which is mainly concentrated in the upstream plate and gate bottom. Finally, the lift force coefficient at the gate bottom is different from the standard and is mainly controlled by the outflow boundary condition. The simulation result is in good agreement with the experiment and the relative error meets engineering requirements, suggesting that the numerical model can successfully simulate the gate fluid–structure interaction and reproduce the characteristics of physical quantities in the closing process.

A fluid–structure interaction model for assessing the safety of flood gate vibrations due to wave impacts

This paper establishes a computationally efficient model to predict flood gate vibrations due to wave impacts including fluid–structure interaction. In contrast to earlier models, composite fluid domains are included to represent the situation of a flood gate in a dewatering sluice with the presence of an overhang that causes the confined-wave impacts. The dynamic response of the gate-fluid system is derived in the frequency domain using a substructuring mode matching technique, in which the gate vibrations are first expressed in terms of in-vacuo modes while the liquid motion is described as a superposition of linear potentials. Pressure impulse theory is employed to predict the impulsive wave impact loads, which are superposed on the quasi-steady wave loads. The computational efficiency of the developed model allows for a large number of simulations. This makes it possible for the first time to perform probabilistic evaluations for this type of problems without doing concessions on the accuracy of the physical modelling of the involved fluid–structure interaction processes. This is demonstrated by application of the developed models within a probabilistic framework resulting in the explicit quantification of the failure probability of flood gates subjected to wave impacts.

Modelling of Flow Patterns over Spillway with CFD (Case Study: Haditha Dam in Iraq)

Spillways are designing to release surplus water over a volume of storage. The excess water flows from the top of the reservoir and is carried back to the river by a spillway. Many radial gates were destroyed under hydrodynamic load. Radial gate connectors are susceptible to fatigue failure due to excessive vibration; therefore, gate vibration during operation must be investigated to confirm safe operation at the design water pressure. Several studies were carried out to analyse and simulation of flow over the spillway. In this article, the flow pattern over the Haditha dam spillway has been simulated using computational fluid dynamics (CFD). The numerical model was performed using Ansys Fluent 2020 R1 to simulate the flow properties; determination of cavitation damage at three discharges corresponding in the design of Haditha dam are 4700, 7140, and 7900 m3/s. In addition to finding the effect of gate vibration under dynamic water loads. The Realisable k-ɛ turbulence model was utilised with the volume of fluid (VOF) model to simulate the interaction between air and water phases. The validation of the numerical model was achieved by comparing it with a physical model. The physical model of the Haditha Dam spillway was made from iron with a scale of 1:110. It has been designed and constructed in a hydraulic laboratory according to the modelling principle of the hydraulic structure. The results showed that a high agreement between the physical and numerical model and the k-ɛ turbulence model could simulate the Haditha dam spillway with low cost and few times. The cavitation damage may occur at the region start at the end of the arching spillway to stretches downstream, and there is no damage of gate vibration under dynamic water load.

Characteristics of Plane Gate Vibration and Holding Force in Closing Process by Experiments

A 1:25 scale physical model test was employed to study the plane gate vibration and holding force under the conditions of the fixed gate opening and closing process, respectively. We paid more attention to the characteristics of the gate vibration, holding force and the failure of gate-closing in closing process. The correlation between gate vibration and holding force was further examined. The results show that vertical vibration is weaker than the lateral and horizontal vibrations in fixed gate opening and is stronger than the lateral and vertical vibrations in closing process. Gate vertical vibration is self-excited vibration with a frequency of 7–14 Hz. Besides, crawl vibration in closing process is related to the upstream water depth. The higher the water level is, the earlier the crawl vibration appears. After the crawl stage, plane gate stops motion at a certain distance from the chamber floor and then the failure of gate-closing happens. Finally, gate vibration in three directions is significantly correlated with the holding force. In closing process, holding force has positive correlation with the vertical vibration and has negative correlation with the lateral and horizontal vibrations. In the crawl stage, the average of correlation coefficient in lateral, vertical and horizontal direction is −0.723, 0.733 and −0.664, respectively. Thus, the influence of gate vibration on holding force should be taken into consideration in determining the hoists capacity.

Analysis of the Cause and Mechanism of Hydraulic Gate Vibration during Flood Discharging from the Perspective of Structural Dynamics

According to the results of a dynamic prototype test for the surface outlet radial gate on the Jinping high arch dam during the flood discharging process, a novel cause of vibration fundamentally different from the traditional causes of flow-induced radial gate vibration, is analyzed for the first time. Under the condition that the flood is discharged only from mid-level outlets, an accompanying vibration of the surface outlet gate is induced by the vibration of the closely spaced mid-level outlet gates. It is counterintuitive that the most intense vibration occurs when the surface outlet gate is closed and, on the contrary, the vibration is reduced when the gate is opened and subjected to flow excitation. In order to analyze and explain this accompanying vibration phenomenon, a theoretical model is developed based on the conventional theory of passive vibration absorbers. The difference between the proposed and conventional theoretical models is that more complex load and damping conditions are considered, and more attention was paid to the dynamic behavior of the accessory structure. Then, the cause and mechanism for the surface outlet gate vibration is clarified in detail, based on the proposed theoretical model. The comprehensive analysis and mutual verification of the prototype test, theoretical derivation and numerical simulation, indicate that the clarification and the proposed theoretical model is reasonable and accurate. The research reported in this paper will be beneficial for the design, operation and maintenance of the hydraulic gates installed on high arch dams.

Calculation models and analysis methods of the parametric vibration of radial gates

Parametric vibration is one of the main reasons for the failures of radial gates. This paper presents three calculation models of the parametric vibration of radial gates which reflect the mechanical properties and geometric features of the gates. Two most commonly used analysis methods, i.e., Bolotin’s method and the finite element method, were described to determine the boundaries of regions of the dynamic instability of radial gates. A numerical example concerning finite element method was also demonstrated.

A three dimensional semi-analytical model for the prediction of gate vibrations immersed in fluid

A model is developed to predict bending vibrations of flood gates with fluid on both sides. The liquid flow is three-dimensional and the gate is represented as a thin plate. The fluid response is considered within the linear potential flow theory including the effect of compressibility and the generation of free surface waves. This way, the hydrodynamic fluid pressure exerted on the gate is predicted accurately in both low and high-frequency regimes. Both the structural and fluid responses are expressed in the modal domain as a superposition of modes. A semi-analytical solution of the fluid-interaction problem is obtained by describing the complete system in terms of in vacuo gate modes, which is computationally efficient compared to existing numerical methods. This allows for the accurate prediction of flood gate vibrations for a large number of simulations, making it possible to perform fatigue calculations and probabilistic evaluations. The case of a typical flat flood gate subjected to an impulsive wave impact is studied with the developed model. Results show the capability of the model to efficiently quantify flood gate vibrations considering the involved fluid-structure interaction, which can lead to more economical designs compared to common engineering practice.

Numerical and Experimental Comparative Study on the Flow-Induced Vibration of a Plane Gate

A numerical method is applied here to simulate the unstable flow and the vibration of a plane gate. A combination of the large eddy simulation (LES) method and the volume of fluid (VOF) model is used to predict the three-dimensional flow field in the vicinity of a plane gate with submerged discharge. The water surface profile, the streamline diagrams, the distribution of turbulent kinetic energy, the power spectrum density curve of the fluctuating pressure coefficient at typical points underneath the gate, and the complete vortex distribution around the gate are obtained by LES-VOF numerical calculation. The vibration parameters of the gate are calculated by the fluid-structure coupling interface transferring the hydrodynamic load. A simultaneous sampling experiment is performed to verify the validity of the algorithm. The calculated results are then compared with experimental data. The difference between the two is acceptable and the conclusions are consistent. In addition, the influence of the vortex in the slot on the flow field and the vibration of the gate are investigated. It is feasible to replace the experiment with the fluid-structure coupling computational method, which is useful for studying the flow-induced vibration mechanism of plane gates.

Lattice Vibration of Layered GaTe Single Crystals

The effect of interlayer interaction on in-layer structure of laminar GaTe crystals was studied according to the lattice vibration using micro-Raman analysis. The results were also confirmed by the first principle calculations. Accordingly, the relationship between lattice vibration and crystal structure was established. Ten peaks were observed in the micro-Raman spectra from 100 cm−1 to 300 cm−1. Eight of them fit Raman-active vibration modes and the corresponding displacement vectors were calculated, which proved that the two modes situated at 128.7 cm−1 and 145.7 cm−1 were related to the lattice vibration of GaTe, instead of impurities or defects. Davydov splitting in GaTe was identified and confirmed by the existence of the other two modes, conjugate modes, at 110.7 cm−1 (∆ω = 33.1 cm−1) and 172.5 cm−1 (∆ω = 49.5 cm−1), indicates that the weak interlayer coupling has a significant effect on lattice vibrations in the two-layer monoclinic unit cell. Our results further proved the existence of two layers in each GaTe unit cell.

Flow-induced vibration of a radial gate at various opening heights

ABSTRACTThis study proposes a method for mitigating the flow-induced vibration of a radial sluice gate to ensure operational safety and long-term stability. To this end, a supplementary plate was attached to the lower rear surface of the gate and its effect on vibration reduction is investigated using a fluid–structure interaction (FSI) analysis. Specifically, a three-dimensional finite-element method (FEM) model of the gate partially submerged in water was constructed and then validated by comparing the numerical responses of the gate with experimental results under the conditions of steady-state discharge. The FSI analysis showed that the vertical vibration acceleration of the gate diminished by 70% after the supplementary plate was attached, thereby reducing the swirling strength calculated from the vortex shedding behind the gate. The Strouhal number describing the intensity of the gate vibration in the flowing fluid was also reduced by 57% after the supplementary plate was attached. The results of this study can be used to inform the design and development of radial gates, as well as maintenance plans for their economical operation.

High-Frequency Noises and Low-Frequency Vibrations of Water Intake Sluice Gates

High-Frequency Noises and Low-Frequency Vibrations of Water Intake Sluice Gates

Flow-induced horizontal and vertical vibration of sluice gates

The present study focuses on out-of-plane and in-plane vibrations of sluice gates due to the fluid–structure interaction based on numerical modelling, using the finite-element method. Primarily, the vibration of the gate was restricted to a single direction, detaching the horizontal and vertical vibrations of the gate so as to exclude their interaction. Results indicated that, if the edge of the gate is bevelled at an angle of 45°, the lowest amplitudes of horizontal vibrations are obtained. Whereas the maximum horizontal vibrations are associated with the uppermost values of the reduced velocities, for example vr > 3·5, as well as the gate's normalised opening height δ/d of about 0·8, the maximum vertical vibrations are attained for intermediate values of vr, at about 3, and δ/d = 0·8. If both the horizontal and vertical vibrations are mutually considered, the two-dimensional reduced velocities vrx and vry and the structural natural frequencies fx and fy become relatively different compared to these of single-way vibrations. Results also indicated that the amplitudes of the horizontal vibrations in the authors' previous analyses were considerably greater than those of single-way horizontal vibrations. The maximum amplitude of the horizontal vibrations was observed to be close to the out-of-plane natural frequency, when 3·5 < vrx < 7 and vry > 10. For vibration frequencies close to the vertical natural frequency fy, however, the dominant vertical vibrations occur for 2 < vry < 4.