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.

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.

Control of Internal Corrosion Of a Products Pipe Line System

CORROSION ◽  
1955 ◽  
Vol 11 (6) ◽  
pp. 31-36
Author(s):  
P. L DeVERTER ◽  
A. W. JASEK
Keyword(s):  
Internal Corrosion ◽  
Line System ◽  
Pipe Line

scholarly journals Research solutions technical - water technology to reduce the water loss for water supply system of Hochiminh city

2013 ◽  
Vol 16 (1) ◽  
pp. 49-57
Author(s):  
Tuan Anh Vo
Keyword(s):  
Water Supply ◽  
Water Loss ◽  
Salt Water ◽  
Treatment Plant ◽  
Water Treatment Plant ◽  
Supply System ◽  
Water Supply System ◽  
The Sustainable Development ◽  
Pipe System ◽  
Pipe Line

The HCMC water supply system have built from the French Colonial period, and developed without planning and systematic study during the war time. In the beginning, this system used for the small town Saigon- Gia Dinh. Today, the capacity of water supply system is 1,85 million m3/day and will increase up to 2,5 million in next few year and up to 4-5 million m3/day according with the HCMC water supply system planning approved by Government. The climate change issues, salt water lever increase, polution... affect directly into the raw water resource of the existing and future water treatment plant. Beside that, the big size water supply transmission pipe line and the distribution water supply system of 06 hydrolique zone in HCMC damaged according with time : bad quality and No- update information of pipe system… It bring the real water loss level in HCMC so high up to 40% - 50% .The acceptable technologies & techniques solution to find the leak, optimal management for the water supply system to reduce the water loss is extremely essential, to support the clean water resources for the sustainable development of the HCM City.

An Experimental Study on the Influence of Structural Damping on Internal Fluid Pressure During a Transient Flow

1990 ◽  
Vol 112 (3) ◽  
pp. 284-290 ◽  
Author(s):  
D. D. Budny ◽  
F. J. Hatfield ◽  
D. C. Wiggert
Keyword(s):  
Experimental Study ◽  
Transient Flow ◽  
Traditional Approach ◽  
Dynamic Pressure ◽  
Fluid Pressure ◽  
Piping System ◽  
Internal Dynamic ◽  
Structural Damping ◽  
Pipe System ◽  
Internal Fluid

The traditional approach to designing a piping system subject to internal dynamic pressure is to restrain the piping as much as possible, and the approximation made in the analysis is to assume no contribution of structural energy dissipation. To determine the validity of this concept and approximation, an experimental study of a piping system was performed to measure the influence of structural damping. A pipe system was designed with a loop that could be turned so that its natural frequency would match that of the contained liquid. It was discovered that a properly sized damper on the piping loop greatly accelerates the decay of the fluid pressure transient. The damper absorbs some energy from the piping, reducing the resulting rebound fluid pressure. When the loop is subjected to forced steady-state vibration, there is a fluid pressure response. The amplitude of that pressure can be reduced by installing an external damper: the stiffer the damper the more effective it is in reducing dynamic pressure.

Comparisons of CFD and Traditional Solutions for Steam Hammer Events

2017 ◽  
Author(s):  
Alex Mayes ◽  
Kshitij P. Gawande ◽  
Dennis K. Williams
Keyword(s):  
Pressure Wave ◽  
Power Plants ◽  
Peak Load ◽  
Critical Length ◽  
Pressure Change ◽  
Piping System ◽  
Valve Closure ◽  
Pipe System ◽  
Closure Time ◽  
Pressure Changes

Sudden pressure changes in the piping system of power plants are inevitable, and thus potential serious damage to large components, piping system, and piping supports is possible. To protect valuable components from such events, abrupt valve closure is employed to restrict the flow and prevent significant incidents and the resulting plant downtime. Unfortunately, when a valve is suddenly closed to prevent damage caused by unexpected events, a pressure wave within the flow is created, which travels upstream and impacts at the pipeline elbows. These events, involving sudden changes in pressure, are known as steam hammer. This steam hammer pressure wave, traveling through the pipe system, is capable of producing significant transient loads and stresses, which can disrupt the piping supports. As such there is a need for further investigation. The pressure wave depends on the characteristics of the flow, valve closure time, the elbow-to-elbow pipe section lengths, and the piping system flexibility. The present study performs a CFD analysis of the fluid experiencing such a sudden pressure change. OpenFOAM is used for this analysis and considers all the flow parameters, valve closure time, and critical length of the straight pipe. The study intends to provide a means of calculating the transient steam hammer loads applied on the pipe elbows, which consequently allows appropriate pipe support selection based upon the resulting peak loads. This computational analysis is compared to analytical methods for peak load determination such as rigid column theory, the Joukowsky method, and the steam hammer method explained by Coccio (1967) and Goodling (1989).

Bolt Strength in Sectional Body Construction of Valves

2019 ◽  
Author(s):  
Bhaskar Shitolé
Keyword(s):  
Rigid Bodies ◽  
Bolted Joints ◽  
Terminal Point ◽  
Piping System ◽  
Valve Body ◽  
Section Modulus ◽  
Creep Characteristics ◽  
Body Construction ◽  
Minimum Requirements ◽  
Body Joints

Abstract ASME B16.34-2017 Section 6.4.2 provides requirements for valves with bolted body joints and threaded body joints. The section states that valves with bodies of sectional construction such that bolted or threaded body joints are subject to piping mechanical loads in addition to the pressure rating for which the valve is designed, shall satisfy the following requirements. For bolted joints, the requirement is a simple formula where the product of pressure rating class designation and ratio of area bounded by the effective outside periphery of a gasket or O-ring or other seal-effective periphery and total effective bolt tensile stress area are less than a certain constant. For bolts of strength less than 137.9 MPa, the value of constant reduces as a multiple of 50.76 times the bolt tensile strength in MPa required or provided in a sectional construction. Section 6.4.3 cautions that the minimum requirements of ASME B16.34 may fall short in scenarios due to valve design, special gaskets, high temperature service, creep characteristics etc. This paper reviews and studies this ASME B16.34 requirement which was triggered by failure of a valve with section body construction in the field. Traditionally valves have been considered as rigid bodies when analyzing a piping system for stresses, support loads, terminal point loads and deflections. The rigid modelling assumes the strength of the valve is much higher than an equivalent straight length of pipe. Some computer programs have a provision that permits modeling the valve as a multiple like 3- or 4-times pipe section modulus. This paper compares the strength of piping and valves based on inherent valve body thickness, body sectional bolting provided and strength of the equivalent piping flanges. The paper makes conclusions for the user to be aware of so that pre-emptive actions can be taken when using valves with sectional body construction.

Phenomenon of labyrinth seal with low static pressure difference and large clearance

2004 ◽  
Vol 7 (1) ◽  
pp. 63-75 ◽  
Author(s):  
K. Shimada ◽  
K. Kimura ◽  
S. Ichikawa ◽  
H. Ohta ◽  
K. Aoki
Keyword(s):  
Pressure Difference ◽  
Static Pressure ◽  
Labyrinth Seal ◽  
Static Pressure Difference

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.

Acoustic Resonance in a Reservoir-Double Pipe-Orifice System

2012 ◽  
Author(s):  
Arris S. Tijsseling ◽  
Qingzhi Hou ◽  
Bjørnar Svingen ◽  
Anton Bergant
Keyword(s):  
Wave Reflection ◽  
Large Diameter ◽  
Acoustic Resonance ◽  
Mode Shapes ◽  
Nonlinear Excitation ◽  
Pipe System ◽  
Fundamental Frequencies ◽  
Supply Pipe ◽  
Constant Head ◽  
Double Pipe

Acoustic resonance in a two-pipe system is simulated with four different models for the periodic excitation. Analytical solutions are provided in full for the three linear excitations. Exact numerical results are presented for the nonlinear excitation. The influence of a large-diameter supply pipe (instead of a constant-head reservoir) on the system’s fundamental frequencies and mode shapes is studied. The peculiar behaviour of wave reflection at an orifice is fully explained.

Sign in / Sign up

Export Citation Format

Share Document