scholarly journals Effects of Surge Tank Geometry on the Water Hammer Phenomenon: Numerical Investigation

2021 ◽  
Author(s):  
Mohammad Mahmoudi-Rad ◽  
Mohammad Najafzadeh
Keyword(s):  
Transient Flow ◽  
Pressure Fluctuations ◽  
Cost Effective ◽  
Initial Section ◽  
Water Hammer ◽  
Surge Tank ◽  
Head Pressure ◽  
Tank Design ◽  
Pressurized Pipelines ◽  
Tank Diameter

Abstract A surge tank, as one of the most common control facilities, is applied to control head pressure level in long pressurized pipelines during the water hammer occurrence. The cost-effective operation of surge tank is highly affected by its characteristics (i.e., surge tank diameter and inlet diameter of surge tank) and can effectively reduce the repercussion of water hammer. This investigation utilized the method of characteristics (MOC) in order to simulate the behavior of transient flow at surge tank upstream and head pressure fluctuations regime for hydraulic system of a hydropower dam. The various types of boundary conditions (i.e., sure tank, reservoir, branch connection of three pipes, series pipes, and downstream valve) were applied to numerically investigate the simultaneous effects of the surge tank properties. In this way, all the simulations of water hammer equations were conducted for nine various combinations of surge tank diameter (D) and inlet diameter of surge tank (d). Results of this study indicated that, for the surge tank design with D=6m and d=3.4m, head pressure fluctuations reached minimum level in the large section of pipeline here is surge tank upstream. Additionally, occurrence of water hammer phenomenon was probable at the initial section of pipeline.

scholarly journals Surge Tank Analysis for Water Hammer Remedy for Long Distance Pipeline

2018 ◽  
Vol 11 (3) ◽  
pp. 47-53
Author(s):  
Nisreen J. Rasheed
Keyword(s):  
Friction Factor ◽  
Method Of Characteristics ◽  
Transient Flow ◽  
Water Hammer ◽  
Pipeline System ◽  
Surge Tank ◽  
Governing Equations ◽  
Long Distance ◽  
Several Variables ◽  
The Impact

Various protection methods can be used for protecting the pipeline system from the impact of water hammer. Which includes the use of special materials for supporting the pipeline and the installation of special devices such as surge tanks, relief valves, and air chambers. In this study, to protect the pipeline system and reduce the effect of water hammer, surge tank has been used. Governing equations of transient flow with and without surge tank is numerically simulated using MATLAB software. Sensitivity analysis was investigated using several variables such as pipe diameter, wave’s velocity and friction factor. Method of characteristics (MOC) was implemented in this study. It was found that the diameter and friction factor of pipe have a significant impact on the results of transient flow and surge tank compared to the effect of wave’s velocity. It has been reached that the capacities of surge tanks at diameter (1m), are (1475m3) at first, second and fourth stages, (1360m3) at third and fifth stages and (570m3) at sixth stage. And at diameter (1.2m), the capacities are (1700m3), (1530m3) and (1475m3) at first, second and third stages respectively. But at diameter (1.4m), the capacities are (1590m3) at first and second stages. For all values of wave’s velocity, the capacities of surge tanks are (1760m3), (1530m3) and (1420m3) at first, second and third stages respectively. But the capacities of surge tanks at friction factor (0.007) are (1810m3), (1585m3) and (1245m3) at first, second and third stages respectively. However, for the capacity of surge tanks at the friction factor (0.008), it was mentioned when the surge tanks capacity of the diameter (1.2m) was mentioned. And when the friction factor is (0.009), the capacities are (1460m3) at first stage, (1415m3) at second and third stages and (570m3) at fourth stage

scholarly journals Damping Pressure Pulsations in a Wave-Powered Desalination System

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Brandon J. Hopkins ◽  
Nikhil Padhye ◽  
Alison Greenlee ◽  
James Torres ◽  
Levon Thomas ◽  
...  
Keyword(s):  
Constant Pressure ◽  
Low Cost ◽  
Pressure Fluctuations ◽  
Cost Effective ◽  
Coastal Communities ◽  
Pressure Pulsations ◽  
Pressure Flow ◽  
Reliable Source ◽  
Effective Option ◽  
Elastic Pipes

Wave-driven reverse osmosis desalination systems can be a cost-effective option for providing a safe and reliable source of drinking water for large coastal communities. Such systems usually require the stabilization of pulsating pressures for desalination purposes. The key challenge is to convert a fluctuating pressure flow into a constant pressure flow. To address this task, stub-filters, accumulators, and radially elastic-pipes are considered for smoothing the pressure fluctuations in the flow. An analytical model for fluidic capacitance of accumulators and elastic pipes are derived and verified. Commercially available accumulators in combination with essentially rigid (and low cost) piping are found to be a cost-effective solution for this application, and a model for selecting accumulators with the required fluidic-capacitance for the intended system is thus presented.

Influence of Surge Tank and Relief Valve on Transient Flow Behaviour in Hydropower Stations

2011 ◽  
Author(s):  
Alireza Riasi ◽  
Ahmad Nourbakhsh
Keyword(s):  
Power Plants ◽  
Transient Flow ◽  
Flow Analysis ◽  
Internal Boundary ◽  
Transient Condition ◽  
Maximum Pressure ◽  
Surge Tank ◽  
Small Hydropower ◽  
Relief Valve ◽  
Hydropower Stations

Unsteady flow analysis in water power stations is one of the most important issues in order to predict undesirable pressure variations in waterways and also probable changes in rotor speed for the power plants safe operation. Installation of surge tank and relief valve is the two main methods for controlling of hydraulic transient. The relief valve is used in several medium and small hydropower stations instead of the surge tank and mounted on the penstock near the powerhouse. The recent generation of relief valves are reliable and beneficial and consist of fully control system that directly conducted by governor. This paper presents a numerical method for transient flow in hydropower stations using surge tank and relief valve. For this purpose the governing equations of transient flow in closed conduit are solved using the method of characteristics (MOC) using unsteady friction. Hydraulic turbine, surge tank and relief valve are considered as internal boundary conditions. The influence of surge tank and also relief valve on the maximum pressure in spiral case and turbine over speed has been studied for a real case. The results show that the transient condition is considerably improved by using a relief valve and this device can be mounted in lieu of an expensive surge tank.

Numerical Simulation of Start-Up Jets in a Mixing Chamber

2010 ◽  
Author(s):  
Chenzhou Lian ◽  
Dmytro M. Voytovych ◽  
Guoping Xia ◽  
Charles L. Merkle
Keyword(s):  
Transient Flow ◽  
Three Dimensional ◽  
Cost Effective ◽  
Grid Refinement ◽  
Mixing Process ◽  
Quantitative Estimates ◽  
Start Up ◽  
Mixing Chamber ◽  
Parametric Analyses ◽  
Transient Mixing

Numerical simulations of a transient flow of helium injected into an established background flow of nitrogen were carried out to identify the dominant features of the transient mixing process between these two dissimilar gases. The geometry of interest is composed of two helium slots on either side of a central nitrogen channel feeding into a ‘two-dimensional’ mixing chamber. Simulations were accomplished on both two- and three-dimensional grids using an unsteady DES approach. Results are compared with experimental measurements of species distributions. Unsteady 2-D solutions give a reasonable qualitative picture of the transient mixing process in the middle of the chamber and enable cost-effective parametric analyses and grid refinement studies. The 2-D solutions also provide quantitative estimates of representative characteristic times to guide the 3-D calculations. The 3-D solutions give a reasonable approximation to span-wise events.

Investigations on Flow Characteristics in Diffuser-Discharge-Channel of Volute Casing

2018 ◽  
Author(s):  
Yandong Gu ◽  
Ji Pei ◽  
Shouqi Yuan ◽  
Jinfeng Zhang ◽  
Ernst Nikolajew ◽  
...  
Keyword(s):  
Cross Sections ◽  
Discharge Channel ◽  
Transient Flow ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Centrifugal Pumps ◽  
Discharge Pipe ◽  
Hydraulic Design ◽  
Flow Loss ◽  
Two Sides

The volute casing used in centrifugal pumps is efficient for the transformation of kinetic energy into pressure energy, however, its asymmetric hydraulic design makes the flow in diffuser-discharge-channel (DDC) inhomogeneous, resulting in unsatisfactory flow patterns. In this study, the unsteady numerical simulations are carried out to investigate the transient flow characteristics in DDC. The accuracy of numerical results is found to agree well with experimental performance and pressure fluctuations. It is observed that the flow in DDC is significantly uneven. At the elbow of DDC, the static pressure on the volute left side (VL) is larger than the volute right side (VR) due to the flow impact and flow separation respectively. Thereby, this high-pressure gradient induces the secondary flow on the cross sections of DDC. Further, there is an obvious dependency of pressure fluctuations in the discharge pipe on the strong interaction between the impeller and tongue, in which four small peaks and four large peaks can be observed. At each moment, the pressure on VL gradually decreases from the inlet of discharge pipe to the pump outlet, while it increases on VR, finally, two sides tend to be the same. The pressure fluctuation intensity gradually becomes equivalent-distributed. In particular, it should be noticed that the energy loss in the diffuser part is larger than the discharge pipe, which requires a redesign concerning hydraulic performance. This study can help to better understand the transient flow characteristics and provide guidance for reducing flow loss in the volute casing.

Surge Tank Design for Storage-Tunnels

2019 ◽  
Vol 109 (S1) ◽  
pp. 72-76
Author(s):  
Wolfgang Richter ◽  
Helmut Knoblauch ◽  
Gerald Zenz
Keyword(s):  
Surge Tank ◽  
Tank Design

scholarly journals Holistic Design Approach of a Throttled Surge Tank: The Case of Refurbishment of Gondo High-Head Power Plant in Switzerland

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3440
Author(s):  
Mona Seyfeddine ◽  
Samuel Vorlet ◽  
Nicolas Adam ◽  
Giovanni De Cesare
Keyword(s):  
Power Plant ◽  
Transient Flow ◽  
Holistic Approach ◽  
Head Loss ◽  
Surge Tank ◽  
3D Numerical Modeling ◽  
Head Loss Coefficient ◽  
Loss Coefficients ◽  
High Head ◽  
Modeling Strategy

In order to increase the installed capacity, the refurbishment of Gondo high-head power plant required a modification of the existing surge tank by installing a throttle at its entrance. In a previous study, the geometry of this throttle was optimized by physical modeling to achieve the target loss coefficients as identified by a transient 1D numerical analysis. This study complements previous analyses by means of 3D numerical modeling using the commercial software ANSYS-CFX 19 R1. Results show that: (i) a 3D computational fluid dynamics (CFD) model predicts sufficiently accurate local head loss coefficients that agree closely with the findings of the physical model; (ii) in contrast to a standard surge tank, the presence of an internal gallery in the surge tank proved to be of insignificant effect on a surge tank equipped with a throttle, as the variations in the section of the tank cause negligible local losses compared to the ones induced by the throttle; (iii) CFD investigations of transient flow regimes revealed that the head loss coefficient of the throttle only varies for flow ratios below 20% of the total flow in the system, without significantly affecting the conclusions of the 1D transient analysis with respect to minimum and maximum water level in the surge tank as well as pressure peaks below the surge tank. This study highlights the importance of examining the characteristics of a hydraulic system from a holistic approach involving hybrid modeling (1D, 3D numerical and physical) backed by calibration as well as validation with in-situ measurements. This results in a more rapid and economic design of throttled surge tanks that makes full use of the advantages associated with each modeling strategy.

Reinforcement Analysis of a Slab Tank

2005 ◽  
Author(s):  
Yogeshwar Hari
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Side Member ◽  
Short Side ◽  
Channel Section ◽  
Finite Element Software ◽  
Head Pressure ◽  
Tank Design ◽  
Critical Requirement ◽  
Static Head

The objective of this paper is to reduce the stresses and deflection of an existing slab tank [2]. The slab tank is to store various criticality liquids used in today’s industry. The preliminary overall dimensions of the slab tank are determined from the capacity of the stored liquids. The slab tank design is broken up into (a) two long side members, (b) two short side members, (c) top head, and (d) bottom head. The slab tank is supported from the bottom at a height by a rectangular plate enclosure. The deflection of the linear space is a critical requirement. The deflection is controlled by providing external supports from the bottom at a height by adjustable bolts. The analysis of the slab tank showed excessive stresses at the concentrated supports. The slab tank was modified by providing reinforcement on the long side members. Several reinforcement arrangements were considered. The slab tank is subjected to two conditions. First, vacuum condition, the long side plates will deflect inwards. Second, internal pressure condition the design pressure consists of working internal pressure plus static head pressure. For this the long side plates will deflect outwards. The heads are designed for internal pressure at the bottom where the pressure is the maximum. The vacuum pressure is not critical. The dimensioned slab tank is modeled using STAAD III finite element software. The slab tank showed excessive stresses. The concentrated supports were removed. The long side member was reinforced by a Channel section. The slab tank analysis was simplified by modeling a single long side member and three cases of Channel section reinforcement were considered. The reinforced arrangement was analyzed by STAAD III finite element software. Further analysis by changing the Channel section by plate reinforcement was found to be better.

scholarly journals Water Hammer Control Analysis of an Intelligent Surge Tank with Spring Self-Adaptive Auxiliary Control System

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2527 ◽  
Author(s):  
Wuyi Wan ◽  
Boran Zhang ◽  
Xiaoyi Chen ◽  
Jijian Lian
Keyword(s):  
Control Function ◽  
Water Hammer ◽  
Control Device ◽  
Control Analysis ◽  
Surge Tank ◽  
Transient Pressure ◽  
Supply Pipe ◽  
Proposed Model ◽  
Vertical Size ◽  
Self Adaptive

The water hammer can cause great risks in water supply pipe systems. A surge tank is a kind of general water hammer control device. In order to improve the behavior of the surge tank, a self-adaptive auxiliary control (SAC) system was proposed in this paper. The system can optimize the response of the surge tank according to the transient pressure. The numerical model and the matched boundary conditions were established to simulate the improved surge tank and optimize the SAC system. Then, various transient responses were simulated by the proposed model with different parameters set. The proposed system is validated by comparing the water hammer process in a river-pipe-valve (RLV) system with and without SAC. The results show that the SAC can greatly improve the water hammer control of the pipeline and the water level oscillation of the surge tank. With the SAC system, the required vertical size of the surge tank can be significantly reduced with the desired water hammer control function.

scholarly journals 1-D Modelling and 3-D Simulation of Confined Bubble Formation and Pressure Fluctuations During Flow Boiling in a Microchannel With a Rectangular Cross-Section of High Aspect Ratio

2009 ◽  
Author(s):  
S. Gedupudi ◽  
Y. Q. Zu ◽  
T. G. Karayiannis ◽  
D. B. R. Kenning ◽  
Y. Y. Yan
Keyword(s):  
Aspect Ratio ◽  
Cross Section ◽  
High Aspect Ratio ◽  
Transient Flow ◽  
Flow Boiling ◽  
Rectangular Cross Section ◽  
Computing Time ◽  
Pressure Fluctuations ◽  
Design Tool ◽  
D Model

A simple 1-D model with low requirements for computing time is required to investigate parametric influences on the potentially adverse effects of pressure fluctuations driven by confined vapour bubble growth in microchannel evaporative cooling systems operating at high heat fluxes. A model is developed in this paper for the particular conditions of a channel of rectangular cross-section with high aspect ratio with a constant inlet flow rate (zero upstream compressibility). (The model will later be extended to the conditions of finite upstream compressibility that lead to transient flow reversal). Some parametric trends predicted by the model are presented. The simplifying assumptions in the model are examined in the light of a 3-D simulation by a commercial CFD code, described in an accompanying paper by the same authors. The predictions of pressure changes are in reasonable agreement. It is suggested that the 1-D model will be a useful design tool.

Sign in / Sign up

Export Citation Format

Share Document