scholarly journals Discussion: “Rigid Water-Column Theory in Water-Hammer Problems” (Swiecicki, Ignacy, 1964, ASME J. Basic Eng., 86, pp. 583–588)

1964 ◽  
Vol 86 (3) ◽  
pp. 588-588
Author(s):  
C. G. Smallridge
Keyword(s):  
Water Column ◽  
Water Hammer

scholarly journals Impact pressure on an orifice plate by a rising water column driven by an air pocket in a vertical riser

2020 ◽  
Vol 81 (5) ◽  
pp. 1029-1038 ◽  
Author(s):  
Yu Qian ◽  
David Z. Zhu
Keyword(s):  
Water Column ◽  
Peak Pressure ◽  
Current Model ◽  
Strong Relationship ◽  
Water Hammer ◽  
Orifice Plate ◽  
Minor Effect ◽  
Initial Water ◽  
Air Pocket ◽  
Riser Height

Abstract Occurrences of storm geyser events have attracted significant attention in recent years. Previous studies suggest that using an orifice plate can reduce the intensity of a geyser event but may induce a water-hammer type of pressure on the orifice plate. This study was conducted to explore the factors that influence the pressure transients when an orifice plate was installed in a vertical riser. A novel model was developed to simulated the movement of a rising water column driven by an air pocket in a vertical riser with an orifice plate on the top. Water-hammer type of pressure occurs when the water column reaches the orifice plate. The current model accurately simulates the dynamics of the water column considering its mass loss due to the flow along the wall of the riser (film flow) and the existence of the orifice plate. It was found that the initial water column length and the driving pressure, as well as the riser material, have a strong relationship with the peak pressure. The riser diameter and riser height have minor effect on the peak pressure. The water-hammer induced peak pressure reaches the maximum when the orifice opening is around 0.2 times the diameter of the vertical riser.

Charts for water hammer in pipelines with air chambers

1977 ◽  
Vol 4 (3) ◽  
pp. 293-313 ◽  
Author(s):  
Eugen Ruus
Keyword(s):  
Water Column ◽  
Pipe Wall ◽  
Water Hammer ◽  
Wall Friction ◽  
Low Resistance ◽  
Discharge Line ◽  
Air Chamber ◽  
Basic Parameters ◽  
Computer Studies

Upsurges and downsurges are calculated and plotted for a simple pump discharge line provided with an air chamber. Basic parameters such as pipeline constant, air chamber parameter, pipe wall friction, and orifice resistance are used. The results of this paper can be used to determine the necessary volume of the air chamber. Computer studies indicate that the assumption of the rigid water column and the concentration of pipe friction at the pump end of the pipeline yields reasonably good results at the pump end; however, because of these assumptions, large errors in estimation of both upsurges and downsurges occur at the midpoint and particularly at the quarter point of the pipeline. Pipe friction has a substantially different effect on surges than that of the orifice resistance; these two effects should therefore be considered separately. A differential orifice is recommended and considered; this orifice should have a low resistance to flow out of the chamber.

Analysis of Passive Water Hammer

1999 ◽  
Author(s):  
Syed M. Husaini ◽  
Asif H. Arastu ◽  
Riyad Qashu
Keyword(s):  
Flow Velocity ◽  
Water Column ◽  
Power Plants ◽  
Cold Water ◽  
Water Hammer ◽  
Saturated Water ◽  
Pipe Segment ◽  
Pressure Surge ◽  
Active Flow

Abstract This paper presents a methodology for the calculation of the severity a type of water hammer called “passive water hammer”. The passage of a cold water column followed by hot saturated water through a restricting orifice causes a reduction in flow velocity and a corresponding increase in pressure. The term passive water hammer was given to this mechanism because there is no active flow intervention required for its initiation. This type of water hammer has been observed in heater drain systems of power plants. An example is given for the calculation of pressure surge and pipe segment forces due to this mechanism.

Rigid Water-Column Theory in Water-Hammer Problems

1964 ◽  
Vol 86 (3) ◽  
pp. 583-588 ◽  
Author(s):  
Ignacy Swiecicki
Keyword(s):  
Water Column ◽  
Pressure Rise ◽  
Water Hammer

Equations and charts for solving pressure-rise problems by the rigid water-column theory are presented with an example of their application. These are compared with the elastic water-column theory and the merits of both are discussed.

Charts for Determining Size of Surge Suppressors for Pump-Discharge Lines

1961 ◽  
Vol 83 (1) ◽  
pp. 43-45
Author(s):  
Carl W. Lundgren
Keyword(s):  
Water Column ◽  
Water Hammer ◽  
Column Separations

Surge suppressors are often used for the control of water-hammer pressures which occur in pump-discharge lines subsequent to power interruptions. This paper includes charts for determining the size of the required suppressors when water-column separations do not occur.

scholarly journals Numerical modelling of pipelines with air pockets and air valves

2016 ◽  
Vol 43 (12) ◽  
pp. 1052-1061 ◽  
Author(s):  
Vicente S. Fuertes-Miquel ◽  
P. Amparo López-Jiménez ◽  
F. Javier Martínez-Solano ◽  
Gonzalo López-Patiño
Keyword(s):  
Numerical Modelling ◽  
Water Column ◽  
Water Hammer ◽  
Extreme Conditions ◽  
Residual Velocity ◽  
Air Pocket ◽  
Air Valve ◽  
Air Pockets

This work considers the behaviour of air inside pipes when the air is expelled through air valves. Generally, the air shows isothermal behaviour. Nevertheless, when the transient is very fast, it shows adiabatic behaviour. In a real installation, an intermediate evolution between these two extreme conditions occurs. Thus, it is verified that the results vary significantly depending on the hypothesis adopted. To determine the pressure of the air pocket, the most unfavourable hypothesis (isothermal behaviour) is typically adopted. Nevertheless, from the perspective of the water hammer that takes place when the water column arrives at the air valve and abruptly closes, the most unfavourable hypothesis is the opposite (adiabatic behaviour). In this case, the residual velocity with which the water arrives at the air valve is higher, and, consequently, the water hammer generated is greater.

Guide-Vane Closing Schemes for Pump-Turbines Based on Transient Characteristics in S-shaped Region

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Wei Zeng ◽  
Jiandong Yang ◽  
Jinhong Hu ◽  
Jiebin Yang
Keyword(s):  
Water Column ◽  
Guide Vane ◽  
Water Hammer ◽  
Rate Of Change ◽  
Transient Processes ◽  
Transient Characteristics ◽  
Storage Station ◽  
Transitional Processes ◽  
Pumped Storage ◽  
Column Pressure

During the transitional processes of load rejection in a pumped-storage station, the S-shaped characteristics of the pump-turbines can result in relatively large water-hammer and pulsating pressures. These pressures and the high runaway speed during transient processes may directly damage the penstocks and shorten the life of the turbine. In this study, different guide-vane closing schemes for reducing the maximum transient pressures, including the water-hammer and pulsating pressures, and runaway speed were investigated, and the principles for improving the closing schemes were theoretically analyzed based on the transient characteristics in the S-shaped region. First, an analytical expression for the rate of change of relative water head during the transitional processes was deduced based on a simplified mathematical model. It reveals the relationship between the slopes of the trajectory at the pump-turbine operating points (defined as trajectory slopes) and the rigid water-column pressure, which approximates the water-hammer pressure considering compressibility. Then, based on the characteristics of the rigid water-column pressure during the transient process and the effects of guide-vane closure on the trajectory slopes, the selection method for a two-phase guide-vane closing scheme was proposed. The method included the technique for choosing the coordinates of the turning point and the closing speed of the guide vane. Furthermore, the pulsating pressures of pump-turbines were discussed under different working regions and guide-vane openings (GVOs). Considering the characteristics of the pulsating pressures and the runaway speed during the transient processes, the advantage of three-phase valve-closing schemes in controlling the pulsating pressures and the runaway speed was clarified. Finally, a series of model tests were conducted on a pumped-storage station model and the measured data fully validated the correctness of our analyses in this work.

scholarly journals Study on Judgment and calculation method of two water column separation water hammer

2018 ◽  
Vol 208 ◽  
pp. 012118
Author(s):  
Li Zhao ◽  
Yusi Yang ◽  
Tong Wang ◽  
Zhangchi Song ◽  
Faming Qin
Keyword(s):  
Water Column ◽  
Calculation Method ◽  
Water Hammer ◽  
Column Separation
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