Flow Induced Vibration of a Steam Control Valve in Middle-Opening Condition

2005 ◽  
Author(s):  
Ryo Morita ◽  
Fumio Inada ◽  
Michitsugu Mori ◽  
Kenichi Tezuka ◽  
Yoshinobu Tsujimoto
Keyword(s):  
Pressure Fluctuation ◽  
3D Structure ◽  
Flow Characteristics ◽  
Control Valve ◽  
Piping System ◽  
Flow Induced Vibration ◽  
Valve Body ◽  
Weak Support ◽  
Side Load ◽  
Attached Flow

In some cases, a steam control valve in a power plant causes a large vibration of the piping system under partial valve opening. For rationalization of maintenance and management of a plant, it is favorable to optimize the valve geometry to prevent such vibration. However, it is difficult to understand the flow characteristics in detail only from experiments because the flow around a valve has a complex 3D structure and becomes supersonic (M>1). Therefore, it is useful to combine experiments and CFD (Computational Fluid Dynamics) for the clarification of the cause of vibration and optimization of valve geometry. In previous researches involving experiment and CFD calculation using “MATIS” code, we found that an asymmetric flow attached to the valve body (named “valve-attached flow”) occurs and pressure increases where the valve-attached flow collides with the flow from the opposite side under the middle opening condition. This high-pressure region rotates circumferentially (named “rotating pressure fluctuation”) and causes cyclic side load on the valve body. However, because we assumed the valve support is rigid, we cannot clarify the interaction between the rotating pressure fluctuation and the valve vibration when the valve stiffness is small. Thus, in this paper, we conducted flow-induced vibration experiments on a valve with a very weak support and investigated the characteristics of the vibration mode under the middle-opening condition. As a result, under the specific lift condition of the region where rotating pressure fluctuation occurs, lock-in phenomena between the rotating pressure fluctuation and the valve vibration occur and large-amplitude vibration can be seen.

CFD Simulations and Experiments of Flow Fluctuations Around a Steam Control Valve

2006 ◽  
Vol 129 (1) ◽  
pp. 48-54 ◽  
Author(s):  
Ryo Morita ◽  
Fumio Inada ◽  
Michitsugu Mori ◽  
Kenichi Tezuka ◽  
Yoshinobu Tsujimoto
Keyword(s):  
Three Dimensional ◽  
Control Valve ◽  
Piping System ◽  
Cfd Simulations ◽  
Valve Body ◽  
Side Load ◽  
Flow Fluctuations ◽  
Partial Opening ◽  
Attached Flow ◽  
High Pressure Region

Under certain opening conditions (partial opening) of a steam control valve, the piping system in a power plant occasionally experiences large vibrations. To understand the valve instability that is responsible for such vibrations, detailed experiments and CFD calculations were performed. As a result of these investigations, it was found that under the middle-opening (partial opening) condition, a complex three-dimensional (3D) flow structure (valve-attached flow) sets up in the valve region leading to a high pressure region on a part of the valve body. As this region rotates circumferentially, it causes a cyclic asymmetric side load on the valve body, which is considered to be the cause of the vibrations.

CFD Calculation and Experiments of Unsteady Flow on Control Valve

2004 ◽  
Author(s):  
Ryo Morita ◽  
Fumio Inada ◽  
Michitsugu Mori ◽  
Kenichi Tezuka ◽  
Yoshinobu Tsujimoto
Keyword(s):  
Compressible Flow ◽  
Pressure Fluctuation ◽  
Flow Characteristics ◽  
Control Valve ◽  
Tvd Scheme ◽  
Small Scale ◽  
Benchmark Tests ◽  
Attached Flow ◽  
Valve Opening ◽  
Type Pressure

A steam control valve causes vibrations of piping when the opening is in the middle condition. For the rationalization of maintenance and management in a plant, valves should be improved, but it is difficult to understand the flow characteristics in detail experimentally because the flow around the valve has a complex 3D structure and becomes supersonic (M>1). Therefore, it is necessary to clarify the cause of vibration and to develop improvements both experimentally and through CFD (Computational Fluid Dynamics) calculation. First, small-scale air experiments are performed. In this experiment, a spike-type pressure fluctuation that rotates circumferentially is observed in a middle valve opening. This fluctuation sometimes changes its rotation direction suddenly, or sometimes stays at the same position. Because of this randomness, FFT analysis cannot reproduce this peak frequency. However, another peak caused by the 1st-mode resonance in the pipe-diameter direction can be seen. After some experiments, a high-precision 3D CFD code for compressible flow, “MATIS”, was developed. This code can calculate an unsteady 3D compressible flow steadily and accurately, with TVD scheme, LU-SGS implicit scheme and inner iterative calculation. This code also includes LES turbulence model for compressible fluid in order to reproduce turbulence flow accurately. To validate this code, first, some benchmark tests such as karman vortex calculation and the calculation of a detached shock position on a sphere are performed. After benchmark tests, CFD calculation of the valve is performed under several valve opening conditions. The mesh number is about 600 thousand and y+ is about 3. CFD results agree well with those of the experiment qualitatively and quantitatively. Therefore, the validation of MATIS is confirmed. Detailed flow characteristics around the valve in a middle valve opening are investigated. Under this condition, the jet after the throat travels the valve (named “attached flow”) and strikes the jet coming from the opposite side. This phenomenon generates a high-pressure region and a pair of vortices; this region rotates circumferentially and causes cyclic side load on the valve body. CFD calculation clarifies that a circumferentially propagating spike-type pressure fluctuation is caused by attached flow along the valve, and this is though to be the cause of vibration.

scholarly journals Flow-Induced Vibration on the Control Valve with a Different Concave Plug Shape Using FSI Simulation

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Akram Zeid ◽  
Mohamed Shouman
Keyword(s):  
High Efficiency ◽  
Complex Structure ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Flow Simulation ◽  
Control Valve ◽  
Low Noise ◽  
Flow Induced Vibration ◽  
Nonlinear Characteristics ◽  
Flow Phenomena

Control valves have always been recognised as being among the most crucial control equipment, commonly utilised in versatile engineering applications. Hence, the need has arisen to identify the flow characteristics inside the valve, together with the incurred vibration induced as a result of the flow passing through the valve. Thanks to the tangible and fast progress made in the field of the flow simulation and numerical techniques, it has become possible to better observe the behavior of the flow passing inside a valve with view to examining its performance. Hence, the paper at hand is mainly concerned with introducing the modeling and simulation of a control valve. On the contrary, the flow system in a control valve is marked by a complex structure and nonlinear characteristics. The reasons for those qualities could be attributed to its construction as well as the fluid flow phenomena associated with it. It is especially for the sake of investigating and observing the flow characteristics, pertaining to a control valve equipped with different concave plug shapes and different openings, that the three-dimensional FSI simulation is conducted. In addition, it would be possible to make use of the obtained results relating to the three-dimensional analysis to achieve low noise and high efficiency improvement. Furthermore, all results will be validated on experimental grounds.

Pressure Fluctuations Around Steam Control Valve: Steam Experiments and CFD Calculations

2007 ◽  
Author(s):  
Ryo Morita ◽  
Fumio Inada
Keyword(s):  
Power Plant ◽  
Pressure Fluctuations ◽  
3D Structure ◽  
Flow Characteristics ◽  
Control Valve ◽  
Working Fluid ◽  
Complex Flow ◽  
Piping Systems ◽  
The Difference ◽  
Complex Flow Structure

In some cases, a steam control valve (figure 1) in a power plant causes large vibrations in piping systems that can be attributed to pressure fluctuations generated in the valve under the partial-valve-opening (middle-opening) condition. For the maintenance and the management of the plant, the valve system needs to be improved to prevent the onset of hydrodynamic instabilities. However, in the case of the steam control valve, it is difficult to understand the flow characteristics in detail experimentally because the flow around the valve has a complex 3D structure and becomes supersonic (M>1). For these reasons, the details of the flow around the valve are not fully understood before, and CFD simulations are required to understand the underlying complex flow structure associated with the valve. In our previous researches, a mechanism of the pressure fluctuations in the middle opening condition, named “rotating pressure fluctuations”, were clarified and a suppression shape were developed by experiments and CFD calculations. However, as we used air as a working fluid in our previous researches instead of steam that is used in the power plant, we couldn’t consider effects of condensation and difference of change of the state quantities between air and steam. In this report, we have conducted steam experiments and CFD calculations by original code to clarify the effects of the difference of the fluids. As a result, in the middle opening condition, we have observed spike-type pressure fluctuations and their rotation in the experiment, and valve-attached flow and local high-pressure region in the CFD result. These results indicate the pressure fluctuations observed in steam experiments and CFDs are the same as rotating pressure fluctuations observced in air researches.

scholarly journals Experimental and Numerical Research on Flow-Induced Vibration in Valves

2017 ◽  
Vol 13 (2) ◽  
Author(s):  
Asmaa Ali Hussein
Keyword(s):  
Finite Element ◽  
Flow Rate ◽  
Vortex Shedding ◽  
Flow Characteristics ◽  
Operating Mode ◽  
Structural Vibration ◽  
Piping System ◽  
Flow Induced Vibration ◽  
Finite Element Software ◽  
Operation Conditions

Abstract   All central air conditioning systems contain piping system with various components, sizes, material, and layouts. If such systems in operating mode, the flow in piping system and its component such as valves can produce severe vibration due to some flow phenomenon’s. In this research, experimental measurements and numerical simulation are used to study the flow-induced vibration in valves. Computational fluid dynamics (CFD) concepts are included with one-way and two-way fluid-structure interaction concepts by using finite element software Package (ANSYS 14.57). Detection analysis is performed on flow characteristics under operation conditions and relations with structural vibration. Most of real geometrical, operational, and boundary conditions are simulated to obtain best similarity with real operation conditions. Comparisons performed between experimental data and numerical results (one-way and two-way simulation) to verify the results. The main conclusion was drawn from the study that the dominant source of vibration for valve is the water pulsation in addition to amount of water hammering. In addition, the main source of water pulsation in globe valve is the vortex shedding and pressure difference between upstream and downstream of valve. The vibration amplitude was increased with increasing flow rate until to be maximum when the flow rate around 30% and then decreased until flow rate reaches to around 85% and then trends to be constant. Keywords: Flow-induced vibration, vortex shedding, pressure pulsation, valve, finite element, ANSYS, fast Fourier transform (FFT).

Pressure Fluctuation Characteristics of Complex Turbulent Flow in a Single Elbow With Small Curvature Radius for a Sodium-Cooled Fast Reactor

2010 ◽  
Vol 132 (11) ◽  
Author(s):  
Shinji Ebara ◽  
Yuta Aoya ◽  
Tsukasa Sato ◽  
Hidetoshi Hashizume ◽  
Yuki Kazuhisa ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Fast Reactor ◽  
Pressure Fluctuation ◽  
Scale Model ◽  
Curvature Radius ◽  
Piping System ◽  
Flow Induced Vibration ◽  
Good Correspondence ◽  
High Reynolds

A multi-elbow piping system is adopted for the Japan sodium-cooled fast reactor (JSFR) cold-legs. Flow-induced vibration (FIV) is considered to appear due to complex turbulent flow with very high Reynolds number in the piping. In this study, pressure measurement for a single elbow flow is conducted to elucidate pressure fluctuation characteristics originated from turbulent motion in the elbow, which lead potentially to the FIV. Two different scale models, 1/7- and 1/14-scale simulating the JSFR cold-leg piping, are tested experimentally to confirm whether a scale effect in pressure fluctuation characteristics exists. A distinguishing peak can be seen in each power spectrum density (PSD) profile of pressure fluctuation obtained in and downstream of the flow separation region for both scaled models. When nondimensionalized, the PSD profiles show good correspondence regardless of scale model and even of Reynolds number simulated in this study.

Steam Plant Piping Vibration Study and Resolution

2007 ◽  
Author(s):  
Gregory Zysk ◽  
John Giamarino
Keyword(s):  
Flow Control ◽  
Distribution System ◽  
Dynamic Pressure ◽  
Control Valve ◽  
Piping System ◽  
Flow Control Valve ◽  
Flow Induced Vibration ◽  
Pressure Transducers ◽  
Equipment Operation ◽  
Generation Plant

The world’s largest district steam co-generation plant was successfully brought on line following major modifications in the spring of 2005. During the initial “shake-down” operation of the high pressure steam send-out system, piping vibrations were experienced, which disrupted flow meters and other equipment. Operation of one of five identical flow control valves, used in parallel to regulate steam flow to the street distribution system, resulted in the high vibration levels. To investigate the cause of the vibrations, a project was undertaken, which included testing of the piping system utilizing dynamic pressure transducers and accelerometers and engineering analysis of the acoustics and piping structural dynamics. Multiple combinations of open and closed valves were investigated, and the likely root cause was identified as flow-induced vibration originating at a tee in the system. A piping layout modification was designed. The modification consisted of rerouting the piping downstream of one flow control valve to bypass the source of the flow-induced vibration. Following the piping modification, further tests were conducted that showed the reconfiguration successfully mitigated the vibration.

Pressure Measurement Test of Single Elbow Simulating Na Cooled Fast Reactor Cold-Leg Piping

2010 ◽  
Author(s):  
Shinji Ebara ◽  
Yuta Aoya ◽  
Tsukasa Sato ◽  
Hidetoshi Hashizume ◽  
Kazuhisa Yuki ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Fast Reactor ◽  
Pressure Fluctuation ◽  
Pressure Measurement ◽  
Power Spectrum Density ◽  
Piping System ◽  
Complex Flow ◽  
Flow Induced Vibration ◽  
Spectrum Density ◽  
Very High

Regarding the Japan Sodium-cooled Fast Reactor, a multi-elbow piping system is adopted for its cold-legs. Flow Induced Vibration (FIV) is considered to be caused by complex flow with very high velocity in the elbows. In this study, pressure measurement test of a single elbow flow is conducted to find out pressure fluctuation characteristic which is related to the elbow turbulent flow and lead potentially to the FIV. Two types of experimental loops, that is, 1/7 and 1/15-scale setup simulating the JSFR cold-leg pipings, are used for pressure measurement, and a distinguishing peak can be seen in the power spectrum density profile of pressure fluctuation obtained where flow separation occurs and at the downstream from it. This characteristics of pressure fluctuation is obtained from the two different scale experiments, and the scale effect is not found in terms of the pressure fluctuation.

Acoustic Fatigue of a Steam Dump Pipe System Excited by Valve Noise

2001 ◽  
Vol 123 (4) ◽  
pp. 461-468 ◽  
Author(s):  
Suzanne Michaud ◽  
Samir Ziada ◽  
Henri Pastorel
Keyword(s):  
Control Valve ◽  
Primary Source ◽  
Scale Model ◽  
Dynamic Strain ◽  
Small Scale ◽  
Piping System ◽  
Frequency Noise ◽  
Valve Body ◽  
Pipe System ◽  
Valve Stem

The steam dump system in Gentilly Nuclear Power Plant consists of four parallel steam pipes, each of which comprises a steam control valve. Two pipes of this system experienced high-cycle fatigue damage. In-situ vibration and dynamic strain measurements were therefore conducted to identify the cause of the damage and formulate suitable counter-measures. The test results pointed to the high-frequency noise of the valve as the primary source causing the fatigue failure. By means of small-scale model tests, using a compressed air network, a new valve stem was developed, which produces a substantially lower noise level than that generated by the original valve stem. Implementing this new stem in the plant, without any other modifications in the valve body or the piping system, significantly reduced the dynamic stresses of the piping, but increased the vibration level of the valve itself. An alternative valve stem, which is a simpler version of the new design, was therefore tested and found to reduce the pipe stresses sufficiently while not increasing the level of valve vibration.

Experimental Study of Two-Phase Flow Induced by Cavitation Through a Safety Relief Valve

2013 ◽  
Author(s):  
Jorge Pinho ◽  
Patrick Rambaud ◽  
Saïd Chabane
Keyword(s):  
Local Minimum ◽  
Two Phase Flow ◽  
Flow Characteristics ◽  
Control Valve ◽  
Recovery Factor ◽  
Phase Flow ◽  
Relief Valve ◽  
Two Phase ◽  
Blow Down ◽  
Choked Flow

The goal of this study is to understand the behavior of a safety relief valve in presence of a two-phase flow induced by cavitation, in which the mass flux tends to be reduced. Two distinct safety relief valves are tested: an API 2J3 type and a transparent model based on an API 1 1/2G3 type. Instead of using a spring, the design of both valves allows the adjustment of the disk at any desired lift. Tests are conducted with water at ambient temperature. Results show a similar influence of cavitation on the flow characteristics of both valves. The liquid pressure recovery factor FL, which is normally used to identify a choked flow condition in a control valve, is experimentally determined in a safety relief valve. The existence of a local minimum located at a height position L/D = 0.14 indicates in this position, a change on the flow characteristics of both valves. It is verified that the existence of a local minimum in the liquid recovery factor is related to the minimum cross section of the flow, which does not remain constant for every lift positions. Furthermore, it is remarked that in the case of the 2J3 safety valve, the blow down ring adjustment has significant influence on the location of the minimum cross sections of the flow.

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