Vibration Experiments and Numerical Simulations of Pulsation Behavior in Actual Size Mock-Up Piping

2010 ◽  
Author(s):  
Akira Maekawa ◽  
Tsuneo Takahashi ◽  
Takashi Tsuji ◽  
Michiyasu Noda ◽  
Minoru Kato ◽  
...  
Keyword(s):  
Boundary Condition ◽  
Nuclear Power ◽  
Pressure Pulsation ◽  
Acoustic Resonance ◽  
Plunger Pump ◽  
Resonance Behavior ◽  
Inner Pressure ◽  
Opening Ratio ◽  
Valve Opening ◽  
Actual Size

Vibration experiments for pressure pulsation behavior were made using actual size mock-up piping of nuclear power facilities. The mock-up was a closed loop consisting of a three-strand plunger pump, tanks, piping and valves. It was 40 m long to allow interaction of the acoustic resonance frequency of fluid inside with the mechanical natural frequency of the piping. The influence of valve closing and opening operations to change inner pressure during pump operations on the pulsation boundary condition was investigated in this study. A drastic change in the boundary condition of the acoustic resonance behavior by using a slightly different valve opening ratio to set a different inner pressure was shown in the experimental results. The phenomenon was numerically simulated by using the method of characteristics. The simulation results showed that the boundary condition of the acoustic resonance changed from the closing-opening condition to the closing-closing condition when the valve opening ratio was changed slightly from 10% to 15%. This indicated that the boundary condition of the acoustic resonance had a pulsed change. Therefore, the boundary condition of the acoustic resonance was sensitive to a slight change of the valve opening ratio.

Experiment and Simulation on Pressure Pulsation Accompanied by Acoustic Resonance and Piping Vibration

2011 ◽  
Author(s):  
Takashi Tsuji ◽  
Akira Maekawa ◽  
Tsuneo Takahashi ◽  
Michiyasu Noda ◽  
Minoru Kato ◽  
...  
Keyword(s):  
Pressure Pulsation ◽  
Fluid Pressure ◽  
Control Valve ◽  
Acoustic Resonance ◽  
Pressure Control ◽  
Piping System ◽  
Knowing That ◽  
Opening Ratio ◽  
Pressure Control Valve ◽  
Improve Condition

To improve condition-based maintenance (CBM) techniques for operating plants, it is necessary to investigate, by experiments and numerical simulations, on the behavior of fluid inside piping system in detail. This study was conducted using the full-scale piping system under conditions that could seriously threaten the plant operation, by matching pressure pulsation, acoustic resonance and piping natural frequency. Although piping vibration is reported to influence fluid pressure pulsation, there were few examples of such influence in the conditions of this experiment. Knowing that the opening ratio of the pressure control valve affects the boundary condition for acoustic resonance, the experiment and numerical simulation at different opening ratios were conducted. It was suggested that there are cases in which a valve partially open at 25% or less shouldn’t be taken as a closed end. This finding conflicts with widespread design assumption.

Simulation of Flow-Induced Acoustic Resonance of Bluff Bodies in Duct Flow

2010 ◽  
Author(s):  
Erick Reyes ◽  
Shane Finnegan ◽  
Craig Meskell
Keyword(s):  
Boundary Condition ◽  
Rigid Body ◽  
Acoustic Field ◽  
Potential Flow ◽  
Acoustic Resonance ◽  
Acoustic Mode ◽  
Bluff Bodies ◽  
Duct Flow ◽  
Body Vibration ◽  
Spacing Ratio

It is well known that the periodic vortex shedding from bluff bodies in a duct can excite the transverse acoustic mode if the frequencies are comparable. There is a considerable body of experimental work investigating this phenomenon for multiple cylinders. Numerical studies are somewhat less common, partially because it is difficult to couple the acoustics and the hydrodynamic field. This paper implements a hydrodynamic analogy proposed by Tan et al. in which the acoustic field is represented by a velocity excitation of the incompressible hydrodynamics at the domain extents. Two alternatives to this boundary condition are considered: rigid body vibration and surface potential flow. In all three cases, the flow field for two tandem cylinders with a spacing ratio of 2.5D has been simulated with uRANS and an RSM turbulence model. It has been found that a rigid body vibration is not a good model of acoustic excitation. However, imposing a potential flow at the surface of the cylinders yields promising results. The success of the new boundary condition implies that the coupling between the acoustic field and the hydrodynamics is not reorganizing the wake directly, but rather simply modifying the generation of vorticity at the surface. Furthermore, it is envisaged that the new modeling approach will be easier to implement for complex geometries, such as tube arrays.

Feasibility Study for Flow-Induced Vibration in Stud Pipe Using Computational Fluid Dynamics

2020 ◽  
Author(s):  
Khac-Ha Nguyen ◽  
Won-Tae Kim ◽  
Seung-Pyo Hong ◽  
Haein Lee ◽  
Ahram Lee
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Vortex Shedding ◽  
Pressure Pulsation ◽  
Computing Time ◽  
Acoustic Resonance ◽  
Piping System ◽  
Turbulent Model ◽  
Relief Valve ◽  
Pipe Length

Abstract Piping systems in a nuclear plant can be damaged by high-cycle fatigue due to acoustic-induced vibration. Moreover, if the frequency of the vibration in the piping system is overlapped with a natural frequency of the piping, the magnitude of the amplitude will be increased resulting in many problems. For example, the damage is considered as flow-induced acoustic resonance at the branch pipes of the safety relief valve in the main steam lines. This study has investigated the Computational Fluid Dynamics (CFD) analysis methodology to predict and quantify the vortex shedding frequencies and the pressure pulsation magnitude in the dead-end piping system. In order to estimate the vortex shedding vibration, a high level turbulent model should be applied. Such a turbulent model, however, requires a substantial amount of computing time. Therefore, the purpose of the study is to investigate the effects of the main pipe length and the sublayer inflation rate on the vortex shedding frequency and pressure pulsation magnitude. The results for the effects will be able to reduce the size of the fluid domain so that the computing time can be significantly decreased in using the high resolution turbulent models.

Suppression Methods of Acoustic Noise Generated in Main Steam Stop Valve

2018 ◽  
Author(s):  
Shiro Takahashi ◽  
Eiji Ozaki ◽  
Atsuyuki Minenaga
Keyword(s):  
Pressure Loss ◽  
High Speed ◽  
Nuclear Power ◽  
Power Plants ◽  
Acoustic Noise ◽  
Acoustic Resonance ◽  
Stop Valve ◽  
Cfd Analyses ◽  
Main Steam Line ◽  
Main Steam

The main steam stop valve (MSSV) is installed in the main steam line in thermal and nuclear power plants. The MSSV is a safety valve that instantaneously shuts off the steam flowing into the steam turbine in an emergency. However, as high-speed steam flow goes through the MSSV during even the rated operation, acoustic sound or noise is generated in the MSSV. Moreover, there is a possibility that flow-induced acoustic resonance occurs in the MSSV. Flow-induced acoustic resonance must be suppressed to decrease the sound noise. Reducing the pressure loss of the MSSV is also an important issue that cannot be neglected with respect to the plant thermal efficiency. Therefore, we have developed the MSSV which can suppress the flow-induced acoustic resonance and its pressure loss. To develop this MSSV, we conducted scale air tests and computational fluid dynamics (CFD) analyses that are described in this paper. Mach and Strouhal number of the test conditions were the same as those of an actual plant. Reynolds number was sufficiently large to obtain the developed turbulent flow. An unsteady compressible CFD analysis was also conducted using large eddy simulation as a turbulence model. We developed new tilted triangular tabs and installed them in the MSSV to suppress the intense vortex generation and pressure loss. As a result, the sound noise due to the flow-induced acoustic resonance was completely attenuated and pressure loss was reduced compared to the case using the current tilted tabs. CFD results also showed that the tilted triangular tabs could suppress the generation of intense vortexes and the flow-induced acoustic resonance.

Determination of Thermal-Hydraulic Loads on Reactor Internals in a DBA-Situation

2006 ◽  
Author(s):  
Ville Lestinen ◽  
Timo Toppila ◽  
Antti Timperi ◽  
Timo Pa¨ttikangas ◽  
Markku Ha¨nninen
Keyword(s):  
Boundary Condition ◽  
Nuclear Power ◽  
Break Point ◽  
Mechanical Analysis ◽  
Element Analysis ◽  
Loss Of Coolant Accident ◽  
Design Basis Accident ◽  
Cfd Analyses ◽  
Reactor Internals

According to Finnish regulatory requirements, reactor internals have to stay intact in design basis accident (DBA) situations, so that control rods can always penetrate into the core. This is the basic motivation to study and develop more detailed methods for analyses of thermal-hydraulic loads on reactor internals during the DBA situation in the Loviisa Nuclear Power Plant (NPP) in Finland. In this work, the studied accident situation is Large Break Loss of Coolant Accident (LBLOCA). The objective of this work is to connect thermal-hydraulic and mechanical analysis methods with the goal to produce a reliable method for determination of thermal-hydraulic and mechanical loads on reactor internals in the accident situation. In the present model, the downcomer of a PWR is only included and the reactor internals will be added later. The tools studied are thermal-hydraulic system codes, computational fluid dynamics (CFD) codes and finite element analysis (FEA) codes. Both thermal-hydraulic and mechanical aspects are discussed in this paper. Firstly, the pressure boundary condition in the pipe break point was calculated with the system code. In the second step, CFD analyses were made. Finally, the full fluid-structure interaction coupling between the CFD and FEA codes was used. The codes used for development and simulations are APROS system code for boundary condition calculations, STAR-CD and FLUENT for CFD calculations and ABAQUS for FEA calculations.

scholarly journals Vibration Failure Analysis and Countermeasures of the Inlet Pipelines at a Gas Compressor Station

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Shuangshuang Li ◽  
Liwen Zhang ◽  
Chunyan Kong
Keyword(s):  
Finite Element Method ◽  
Vibration Analysis ◽  
Pressure Pulsation ◽  
Acoustic Resonance ◽  
Processing Capacity ◽  
Compressor Station ◽  
The Finite Element Method ◽  
Design Requirement ◽  
Structure Interaction ◽  
Load Conditions

A gas compressor station only had its about 35% design processing capacity as a result of the abnormal piping vibrations on the inlet pipelines. Characterization, diagnostics, analysis, and elimination of piping vibration were performed. The root causes and sources of the abnormal vibration were investigated by on-site measurements and analysis of vibration and pulsation under various load conditions of compressors. The results revealed that it was not mechanical resonance, but the high pressure pulsation and acoustic resonance occurred on the inlet pipelines, which resulted in the severe vibration. Three different modification models against vibration were proposed by shortening the length of the pipe to avoid acoustic resonance, enlarging the volume of the gathering manifold to buffer pressure pulsation, and adding supports to increase the stiffness. A better modification model was applied by performing modal analysis and fluid-structure interaction (FSI) vibration analysis using the finite element method. The effect of countermeasures was evaluated by vibration and pulsation measurements during operation after modifications, which results showed the level of piping vibration and pressure pulsation was within the allowable limits. The processing capacity of the gas station has reached its design requirement as a result of the desired reduction in vibrations.

scholarly journals Flow in the exit of open pipes during acoustic resonance

1980 ◽  
Vol 99 (2) ◽  
pp. 293-319 ◽  
Author(s):  
J. H. M. Disselhorst ◽  
L. Van Wijngaarden
Keyword(s):  
Boundary Layer ◽  
Mathematical Model ◽  
Boundary Condition ◽  
Acoustic Wave ◽  
Acoustic Waves ◽  
Acoustic Radiation ◽  
Acoustic Resonance ◽  
The Other ◽  
Open Tube ◽  
Theoretical Predictions

The flow near the mouth of an open tube is examined, experimentally and theoretically, under conditions in which resonant acoustic waves are excited in the tube at the other end. If the edge of the tube is round, separation does not occur at high Strouhal numbers, which enables us to verify theoretical predictions for dissipation in the boundary layer and for acoustic radiation. Observation with the aid of schlieren pictures shows that in the case of a sharp edge vortices are formed during inflow. The vortices are shed from the pipe during outflow. Based on these observations a mathematical model is developed for the generation and shedding of vorticity. The main result of the analysis is a boundary condition for the pressure in the wave, to be applied near the mouth. The pressure amplitudes in the acoustic wave measured under resonance are compared with theoretical predictions made with the aid of the boundary condition obtained in the paper.

Theoretical and Finite Element Analysis of Crosshead of Quintuple Cylinders Fracturing Pump

2011 ◽  
Vol 201-203 ◽  
pp. 253-256 ◽  
Author(s):  
Zhi Peng Lv ◽  
Si Zhu Zhou ◽  
Xiu Hua Ma
Keyword(s):  
Boundary Condition ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Maximum Force ◽  
Element Analysis ◽  
Plunger Pump ◽  
Load Handling ◽  
The Finite Element Model

According to the plunger pump movement principle, this paper analyzed the two kind of typical force situation of the crosshead, and obtained the theoretical maximum force. Established the finite element model of the crosshead, gave an analysis to the load handling and boundary condition. The last results of the node stress and displacement show that the crosshead can work safely.

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