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.

Numerical Analysis of Contraction Geometry Effects on Cavitation Choking in a Piping System

2019 ◽  
Author(s):  
Motohiko Nohmi ◽  
Shusaku Kagawa ◽  
Tomoki Tsuneda ◽  
Wakana Tsuru ◽  
Kazuhiko Yokota
Keyword(s):  
Static Pressure ◽  
Sudden Expansion ◽  
Piping System ◽  
Valve Body ◽  
Line System ◽  
Pipe System ◽  
Flow Fluctuation ◽  
Supply Pipe ◽  
Static Pressure Difference ◽  
Pipe Line

Abstract There is a contraction portion in the water supply pipe line system, and cavitation may occur in the contraction when the flow velocity is increased. Such a situation occurs widely in the throat of the fluid machineries and in the vicinity of the valve body of the valve. In operation of the valve, it is well known that a phenomenon occurs in which the flow rate does not increase even if the static pressure difference upstream and downstream of the valve is increased due to the growth of cavitation in the contraction, which is well known as choking . It is not clear what phenomena occurs when cavitation surge occurs in the pipe system in the situation where choking is occurring in the contraction. In this study, cavitation CFD was performed on pipes those have three different geometry contractions. It was revealed that choking occurred when cavitation occurred in any shape. Also, in the case with the sharp contraction part and the sudden expansion, the flow fluctuation at the upstream of the contraction is much weaker than that at the downstream, but in the contraction with the bent part where the centrifugal force acts on the flow, the flow fluctuation at the upstream was found to be strong.

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.

Experimental and Numerical 3D Study of Flow-Sound Interaction in a Steam-Line Gate Valve

2013 ◽  
Author(s):  
Romain Lacombe ◽  
Philippe Lafon ◽  
Frédéric Daude ◽  
Fabien Crouzet ◽  
Samir Ziada ◽  
...  
Keyword(s):  
Shear Layer ◽  
Gate Valve ◽  
Companion Paper ◽  
Acoustic Mode ◽  
Scale Model ◽  
Small Scale ◽  
Piping System ◽  
Tonal Noise ◽  
3D Geometry ◽  
Piping Systems

Piping systems conveying gases at high pressure often generate high level of vibration and noise. These phenomena, in many cases, are initiated by the coupling between an unstable separated flow and an acoustic mode of the piping system. Various types of cavities in pipe flow are among the flow geometries which are known to be liable to the generation of tonal noise. Flow over cavities in ducts and piping systems has been investigated extensively for two and three dimensional situations. In this case, the feedback loop which generates the tonal noise is caused by the coupling between the instability of the shear layer forming at the cavity opening and an acoustic mode. This paper presents a study of tonal noise generation by subsonic pipe flows over a cavity formed inside a fully open gate valve. Previous 2D and 3D studies, presented in a companion paper, have shown that the presence of the valve-seat cavity is responsible for the generation of acoustic tonal noise. In this paper, the full 3D geometry of the valve, on a small scale model, is studied with experiments and using an unsteady compressible flow solver developed at EDF. Experimentally, the evolution of the fluid acoustic coupling in term of frequency and amplitude with the flow velocity is studied. Also, a modal analysis have been done to identify the frequency of acoustic mode of the valve. Numerically, the complex 3D geometry is meshed and computation is performed. The results show an acoustic tonal noise in a frequency range compatible with that experimentally. The study is underway, future analysis of the velocity and acoustic fields in the simulation may help to identify the shear layer and acoustic modes and to identify how they couple together.

scholarly journals Investigation on Seismic Damage Model Test of a High Concrete Gravity Dam Based on Application of FBG Strain Sensor

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Mingming Wang ◽  
Jianyun Chen ◽  
Hai Wei ◽  
Bingyue Song ◽  
Weirong Xiao
Keyword(s):  
Strain Gauge ◽  
Safety Evaluation ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Model Material ◽  
Gravity Dam ◽  
Scale Model ◽  
Dynamic Strain ◽  
Small Scale ◽  
Small Scale Model

A 203-m-high gravity dam being built in earthquake-prone areas needs to be investigated very carefully to determine its dynamic responses, damage mechanism, and safety evaluation. The dynamic characteristics, seismic responses, failure mode, and safety evaluation of the above structure are presented through dynamic fracture test for small-scale model on shaking table. Because the strength of the model material is very low, the traditional strain gauge is also not easy to be glued to the surface of model. It is difficult to measure the accurate strain data of small-scale model during testing. Therefore, Fiber Bragg Grating (FBG) strain sensor is presented to obtain the strain of small-scale model during testing, due to its high sensitivity. The dynamic strain and residual strain are obtained with the FBG sensors embedded in model. The FBG sensor is adhered to model material completely and shows advantages of ease for installation, high sensitivity, and reliability compared with traditional resistance strain gauge. The model during testing is submitted with earthquake wave from the Chinese Code. In the experiment, the peak ground acceleration (PGA) of the first crack in the model indicates the safety level of the gravity dam. The crack locations and forms determine the damageable part of gravity dam under intense earthquake. After the final analysis, the safety evaluation result of the gravity dam under strong earthquake is given in order to guide the implementation of the project.

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.

RANCANG BANGUN PERANGKAT EKSPERIMENTASI PROSES PIROLISIS BIOMASA GELOMBANG MIKRO

2013 ◽  
Vol 14 (2) ◽  
Author(s):  
Noor Fachrizal
Keyword(s):  
Large Scale ◽  
Continuous Model ◽  
Biomass Energy ◽  
Scale Model ◽  
Small Scale ◽  
Laboratory Apparatus ◽  
Liquid Form ◽  
Large Scale Model ◽  
Bio Oil ◽  
Pyrolysis Of Biomass

Biomass such as agriculture waste and urban waste are enormous potency as energy resources instead of enviromental problem. organic waste can be converted into energy in the form of liquid fuel, solid, and syngas by using of pyrolysis technique. Pyrolysis process can yield higher liquid form when the process can be drifted into fast and flash response. It can be solved by using microwave heating method. This research is started from developing an experimentation laboratory apparatus of microwave-assisted pyrolysis of biomass energy conversion system, and conducting preliminary experiments for gaining the proof that this method can be established for driving the process properly and safely. Modifying commercial oven into laboratory apparatus has been done, it works safely, and initial experiments have been carried out, process yields bio-oil and charcoal shortly, several parameters are achieved. Some further experiments are still needed for more detail parameters. Theresults may be used to design small-scale continuous model of productionsystem, which then can be developed into large-scale model that applicable for comercial use.

scholarly journals Experimental Study on the Behavior of Existing Reinforced Concrete Multi-Column Piers under Earthquake Loading

2021 ◽  
Vol 11 (6) ◽  
pp. 2652
Author(s):  
Jung Han Kim ◽  
Ick-Hyun Kim ◽  
Jin Ho Lee
Keyword(s):  
Seismic Performance ◽  
Seismic Design ◽  
Bridge Piers ◽  
Scale Model ◽  
Inertia Force ◽  
Small Scale ◽  
Lap Splice ◽  
Existing Structures ◽  
Seismic Design Code ◽  
Seismic Force

When a seismic force acts on bridges, the pier can be damaged by the horizontal inertia force of the superstructure. To prevent this failure, criteria for seismic reinforcement details have been developed in many design codes. However, in moderate seismicity regions, many existing bridges were constructed without considering seismic detail because the detailed seismic design code was only applied recently. These existing structures should be retrofitted by evaluating their seismic performance. Even if the seismic design criteria are not applied, it cannot be concluded that the structure does not have adequate seismic performance. In particular, the performance of a lap-spliced reinforcement bar at a construction joint applied by past practices cannot be easily evaluated analytically. Therefore, experimental tests on the bridge piers considering a non-seismic detail of existing structures need to be performed to evaluate the seismic performance. For this reason, six small scale specimens according to existing bridge piers were constructed and seismic performances were evaluated experimentally. The three types of reinforcement detail were adjusted, including a lap-splice for construction joints. Quasi-static loading tests were performed for three types of scale model with two-column piers in both the longitudinal and transverse directions. From the test results, the effect on the failure mechanism of the lap-splice and transverse reinforcement ratio were investigated. The difference in failure characteristics according to the loading direction was investigated by the location of plastic hinges. Finally, the seismic capacity related to the displacement ductility factor and the absorbed energy by hysteresis behavior for each test were obtained and discussed.

Wave Energy Hyperbaric Device for Electricity Production

2007 ◽  
Author(s):  
Segen F. Estefen ◽  
Paulo Roberto da Costa ◽  
Eliab Ricarte ◽  
Marcelo M. Pinheiro
Keyword(s):  
Power Generation ◽  
Wave Energy ◽  
Experimental Results ◽  
Electricity Production ◽  
Scale Model ◽  
Small Scale ◽  
Regular Waves ◽  
Hyperbaric Chamber ◽  
Small Scale Model

Wave energy is a renewable and non-polluting source and its use is being studied in different countries. The paper presents an overview on the harnessing of energy from waves and the activities associated with setting up a plant for extracting energy from waves in Port of Pecem, on the coast of Ceara State, Brazil. The technology employed is based on storing water under pressure in a hyperbaric chamber, from which a controlled jet of water drives a standard turbine. The wave resource at the proposed location is presented in terms of statistics data obtained from previous monitoring. The device components are described and small scale model tested under regular waves representatives of the installation region. Based on the experimental results values of prescribed pressures are identified in order to optimize the power generation.

scholarly journals Roughness Lengths for Momentum and Heat Derived from Outdoor Urban Scale Models

2007 ◽  
Vol 46 (7) ◽  
pp. 1067-1079 ◽  
Author(s):  
M. Kanda ◽  
M. Kanega ◽  
T. Kawai ◽  
R. Moriwaki ◽  
H. Sugawara
Keyword(s):  
Wind Direction ◽  
Roughness Length ◽  
Scale Dependence ◽  
Scale Model ◽  
Small Scale ◽  
Physical Scale ◽  
Scale Models ◽  
Roughness Lengths ◽  
Urban Sites ◽  
Obstacle Height

Abstract Urban climate experimental results from the Comprehensive Outdoor Scale Model (COSMO) were used to estimate roughness lengths for momentum and heat. Two different physical scale models were used to investigate the scale dependence of the roughness lengths; the large scale model included an aligned array of 1.5-m concrete cubes, and the small scale model had a geometrically similar array of 0.15-m concrete cubes. Only turbulent data from the unstable boundary layers were considered. The roughness length for momentum relative to the obstacle height was dependent on wind direction, but the scale dependence was not evident. Estimated values agreed well with a conventional morphometric relationship. The logarithm of the roughness length for heat relative to the obstacle height depended on the scale but was insensitive to wind direction. COSMO data were used successfully to regress a theoretical relationship between κB−1, the logarithmic ratio of roughness length for momentum to heat, and Re*, the roughness Reynolds number. Values of κB−1 associated with Re* for three different urban sites from previous field experiments were intercompared. A surprising finding was that, even though surface geometry differed from site to site, the regressed function agreed with data from the three urban sites as well as with the COSMO data. Field data showed that κB−1 values decreased as the areal fraction of vegetation increased. The observed dependency of the bulk transfer coefficient on atmospheric stability in the COSMO data could be reproduced using the regressed function of Re* and κB−1, together with a Monin–Obukhov similarity framework.

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