Numerical Simulation and Analysis of Hydraulic Excitation System Based on Water Hammer by the Method of Characteristics

2011 ◽  
Vol 295-297 ◽  
pp. 2210-2215 ◽  
Author(s):  
Hui Xian Zhang ◽  
Zi Ming Kou ◽  
Juan Wu ◽  
Chun Yue Lu
Keyword(s):  
Numerical Simulation ◽  
Method Of Characteristics ◽  
Experimental System ◽  
Water Hammer ◽  
Vibration Exciter ◽  
Transient Pressure ◽  
Excitation System ◽  
The Method Of Characteristics ◽  
System Pressure ◽  
Excitation Pressure

To study artificially produced and actively controlled water hammer wave caused by hydraulic vibration exciter, a mathematical model was established and an experimental system was designed to verify it. Through the given partial differential equations, a computer code based on the method of characteristics was developed to calculate transient pressure distributed along the pipe under different rotational frequency of vibration exciter. The numerical simulation indicates that there is a simple harmonic vibration rising at the cross sections along the pipe, corresponding to different excitation pressure at every cross section. In addition, the excitation pressure can also be adjusted by system pressure via overflow valve. So, this work is expected to serve for the optimum design of the hydraulic excitation system and play a theoretical guiding role to experimental research in future.

Numerical Simulation and Experimental Analysis of an Active Hydraulic Excitation System Based on Pulsating Flow

2011 ◽  
Vol 295-297 ◽  
pp. 2216-2222 ◽  
Author(s):  
Zi Ming Kou ◽  
Hui Xian Zhang ◽  
Juan Wu ◽  
Chun Yue Lu
Keyword(s):  
Numerical Simulation ◽  
Frequency Converter ◽  
Experimental System ◽  
Computer Code ◽  
Hydraulic Cylinder ◽  
Pulsating Flow ◽  
Vibration Exciter ◽  
Rotary Speed ◽  
Vibration Wave ◽  
Vibration Parameters

A vibration wave generated actively by hydraulic vibration exciter was studied, and an experimental system based on the theory of water hammer was designed. The new developed vibration exciter is driven by the motor whose rotary speed can be adjusted by frequency converter, by means of which transient pulsating flow is generated regularly. Consequently the piston of hydraulic cylinder is driven periodically with the rotation of vibration exciter. Furthermore, mathematical model was established by the method of characteristics and computer code was developed to calculate numerical solution. The simulation results show that there are different flow velocities distributed at every cross section along the pipe. Measured data is basically consistent with the numerical simulation, which indicates that the vibration parameters of hydraulic cylinder can be controlled effectively.

Numerical Simulation on Dynamic Analysis for Pipe Vibration Control Based on an Actively Generated Hydraulic Excitation Force

2012 ◽  
Vol 490-495 ◽  
pp. 2328-2332 ◽  
Author(s):  
Juan Wu ◽  
Hui Xian Zhang ◽  
Zi Ming Kou ◽  
Chun Yue Lu
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Method Of Characteristics ◽  
Computer Code ◽  
Vibration Exciter ◽  
Lateral Vibration ◽  
System Pressure ◽  
Excitation Force ◽  
Pulsating Fluid ◽  
Pipe Vibration

In order to study dynamic characteristics of fluid filled pipe under hydraulic excitation force generated actively by a new developed vibration exciter, at first mathematical model of pulsating fluid was established and a computer code based on the method of characteristics (MOC) was developed. Then the excitation force calculated by MOC was forced upon the corresponding nodes of finite element of pipe, meanwhile, the nodes of fluid by MOC were assured to coincide with that of the pipe by the method of finite element (FEM). Finally, using Newmark’s method, the dynamic response at every cross section of pipe was solved. The numerical simulations show that a simple harmonic motion arises at every cross section of the pipe. The lateral vibration amplitude of every node along the pipe increases as the rising system pressure. So, this work is expected to provide some theoretical and exploratory basis for studying two dimensional vibration characteristics of fluid filled pipe.

Comparison of computed water hammer pressures with test results for the Çatalan power plant in Turkey

2004 ◽  
Vol 31 (1) ◽  
pp. 78-85 ◽  
Author(s):  
Bülent Selek ◽  
M Salih Kirkgöz ◽  
Zeliha Selek
Keyword(s):  
Power Plant ◽  
Method Of Characteristics ◽  
Water Hammer ◽  
Francis Turbine ◽  
Test Results ◽  
Transient Pressure ◽  
Governing Equations ◽  
Test Procedures ◽  
Conservation Of Momentum ◽  
Pressure Water

The closure of a flow control mechanism at the end of a penstock may cause significant transient pressures. The governing equations of this unsteady flow phenomenon, the conservation of mass and conservation of momentum, are solved by the method of characteristics using various computational schemes. A study was carried out to compare the computational results of the transient pressures with measured prototype data for the Çatalan Power Plant in Turkey. Prototype data were collected during the closure of the wicket gates of a Francis turbine from the test procedures of "load rejection", "emergency shut down", and "quick stop". The numerical results for the transient pressures just upstream of the turbine are compared with the measured data. The general agreement between the theoretical and experimental results is found to be quite reasonable.Key words: transient pressure, water hammer, power plant, Francis turbine, penstock, method of characteristics.

Fundamental Research on Method of Characteristics Based on Cubic Interpolated Profile Scheme in Water Hammer Analysis

2016 ◽  
Author(s):  
Yoshikazu Tanaka ◽  
Akie Mukai ◽  
Hiroyuki Taruya ◽  
Kazuhiko Tsuda
Keyword(s):  
Method Of Characteristics ◽  
Spline Interpolation ◽  
Basic Research ◽  
Linear Interpolation ◽  
Water Hammer ◽  
Interpolation Error ◽  
Computational Grids ◽  
Interpolation Scheme ◽  
Courant Number ◽  
The Method Of Characteristics

This paper introduces basic research conducted to develop a numerical analysis technique for water hammer analysis. The CIP (Cubic Interpolated Profile) scheme was applied to obtain more accurate results without greatly causing a spatial interpolation error depending on the Courant number in the method of characteristics. Regarding this technique, the authors derived a well-formed error formula by applying a linear stability analysis. Characteristics of the interpolation error were clarified by comparing existing interpolation schemes with the method of characteristics. The interpolation error of CIP scheme was superior to the Spatial Linear Interpolation Scheme, was approximately equal to the Time Linear Interpolation Scheme and the cubic spline interpolation scheme with sufficient number of computational grids. The calculation efficiency of the CIP scheme was superior to the other schemes excepting the Spatial Linear Interpolation Scheme.

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