Analysis of Coupled Water Hammer Vibration Equation of Improvement

2014 ◽  
Vol 926-930 ◽  
pp. 2986-2991
Author(s):  
Jian Bing Zhu ◽  
Zhi Min Su ◽  
Zhi Fang Tian ◽  
Xue Lu ◽  
Cheng Jie Jiang
Keyword(s):  
Continuity Equation ◽  
Fluid Structure Interaction ◽  
Water Hammer ◽  
Coupling Vibration ◽  
Fluid Structure ◽  
Vibration Equation ◽  
Structure Interaction ◽  
Continuity Equations

This paper further analyzes some existent problems of coupling vibration equations of water hammer, based on the improved continuity equation, it is derived simply for calculating coupled water hammer vibration, comparison with continuity equation that is to be used widely, the new continuity equation is basically consistent with commonly used continuity equations, so, the improved continuity equation can be used to calculate water hammer based on fluid-structure interaction (FSI).

Two-Way Coupling Fluid–Structure Interaction Analysis and Tests of Shaft Vibration and Clearance Flow Across Plain Annular Seal

2019 ◽  
Vol 86 (10) ◽  
Author(s):  
Kenjiro Miyake ◽  
Tsuyoshi Inoue ◽  
Yusuke Watanabe
Keyword(s):  
Continuity Equation ◽  
Fluid Structure Interaction ◽  
Rotor System ◽  
Design Stage ◽  
Coupling Analysis ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Annular Seal ◽  
Clearance Flow ◽  
Shaft Vibration

Shaft vibration caused by rotor dynamic (RD) fluid force generated by the seal clearance flow has caused several problems. Because such vibration is a coupled phenomenon of clearance flow and shaft vibration, a coupling analysis is essential to solve these problems. In this study, a two-way coupling fluid–structure interaction (FSI) analysis of the seal clearance flow and shaft vibration of a rotor system was conducted and verified through experiments. The rotor system used was a vertical, flexible rotor system with a plain annular seal. In the numerical analysis of the seal clearance flow, the continuity equation and momentum equations, which were averaged across the film thickness, were numerically solved. To suppress the numerical instability, which is unique to the coupling analysis, and improve its numerical stability, a method of successively correcting pressure and shaft acceleration values was adopted so that the continuity equation and rotor equations of motion could be satisfied at every time step. By performing the coupling simulation, the frequency response characteristics of whirling amplitude and leakage flow were investigated. In regard to the stability of the system, the rotational speeds at which self-excited vibration occurs (onset speed of instability: OSI) in its increasing condition and ceases (onset speed of dropdown: OSD) in its decreasing condition were investigated. The coupling analysis results reasonably agree with the experimental results, which demonstrate the validity of the analysis method. In addition, the influence of static eccentricity and whirling amplitude on stability (OSI and OSD) was clarified, which are useful in the design stage of turbomachinery.

Numerical Simulation of Fluid-Structure Interaction with Water Hammer in a Vertical Penstock Subjected to High Water Head

2013 ◽  
Vol 860-863 ◽  
pp. 1530-1534
Author(s):  
Hong Ming Zhang ◽  
Li Xiang Zhang
Keyword(s):  
Interaction Analysis ◽  
Fluid Structure Interaction ◽  
Shell Element ◽  
Water Source ◽  
High Water ◽  
Water Hammer ◽  
Curvilinear Coordinates ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Weakly Compressible

The theoretical model of weakly compressible coupling water hammer was established and a FSI program code was developed for coupled weakly compressible water with penstock movement. It combines the weakly compressible water source CFD code and FEM shell element code. The shell element based on orthogonal curvilinear coordinates was completed in FEAP. Meanwhile, the turbulence model in OpenFoam class library was called by using object-oriented technology. This code takes into account both the weak compressibility of water and fluid turbulence characteristics. Using this code, a fluid structure interaction analysis with water hammer was completed. The numerical results agree well with the field test results.

scholarly journals Fluid-Structure Interaction Response of a Water Conveyance System with a Surge Chamber during Water Hammer

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1025 ◽  
Author(s):  
Qiang Guo ◽  
Jianxu Zhou ◽  
Yongfa Li ◽  
Xiaolin Guan ◽  
Daohua Liu ◽  
...  
Keyword(s):  
Dynamic Pressure ◽  
Fluid Structure Interaction ◽  
Water Hammer ◽  
Equation Model ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Water Conveyance ◽  
Junction Coupling ◽  
Poisson Coupling ◽  
Volume Method

Fluid–structure interaction (FSI) is a frequent and unstable inherent phenomenon in water conveyance systems. Especially in a system with a surge chamber, valve closing and the subsequent water level oscillation in the surge chamber are the excitation source of the hydraulic transient process. Water-hammer-induced FSI has not been considered in preceding research, and the results without FSI justify further investigations. In this study, an FSI eight-equation model is presented to capture its influence. Both the elbow pipe and surge chamber are treated as boundary conditions, and solved using the finite volume method (FVM). After verifying the feasibility of using FVM to solve FSI, friction, Poisson, and junction couplings are discussed in detail to separately reveal the influence of a surge chamber, tow elbows, and a valve on FSI. Results indicated that the major mechanisms of coupling are junction coupling and Poisson coupling. The former occurs in the surge chamber and elbows. Meanwhile, a stronger pressure pulsation is produced at the valve, resulting in a more complex FSI response in the water conveyance system. Poisson coupling and junction coupling are the main factors contributing to a large amount of local transilience emerging on the dynamic pressure curves. Moreover, frictional coupling leads to the lower amplitudes of transilience. These results indicate that the transilience is induced by the water hammer–structure interaction and plays important roles in the orifice optimization in the surge chamber.

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