Waterhammer Analysis of Pump Discharge Line With Several One-Way Surge Tanks

1967 ◽  
Vol 89 (4) ◽  
pp. 621-627
Author(s):  
H. Miyashiro
Keyword(s):  
Water Column ◽  
Digital Computer ◽  
Pump System ◽  
Column Separation ◽  
Discharge Line ◽  
Fundamental Equations

In some pumping plants several one-way surge tanks are installed to prevent water-column separation in the discharge line caused by failure of power to pumps. This paper describes a method of analysis of waterhammer in a pump system of this type. The analysis is carried out by solving the fundamental equations by a digital computer. An example is calculated and the results are compared with the measurements.

Charts for water hammer in low head pump discharge lines resulting from water column separation and check valve closure

1984 ◽  
Vol 11 (4) ◽  
pp. 717-742 ◽  
Author(s):  
Eugen Ruus ◽  
Bryan Karney ◽  
Farouk A. El-Fitiany
Keyword(s):  
Water Column ◽  
Pressure Rise ◽  
Check Valve ◽  
Pressure Head ◽  
Maximum Pressure ◽  
Valve Closure ◽  
High Point ◽  
Column Separation ◽  
Discharge Line ◽  
Low Head

Maximum pressure head rises resulting from water column separation and check valve closure are calculated and plotted for a simple low head pump discharge line with one well-defined high point. Basic parameters such as pipeline constant, pipe wall friction, complete pump characteristics, pump inertia constant, and the relative location of the high point are accounted for in the analyses. The results of this paper can be used to determine (a) when water column separation is expected, (b) how to avoid water column separation, and (c) the necessary wall thickness in cases where no protection against water column separation is provided. Computer studies indicate that both the vertical and horizontal location of the high point as well as the pipe friction, the pipeline constant, and the pump inertia have a major effect on pressure head rises. Water column separation does not always constitute a danger to the pipeline. Key words: waterhammer, water column separation, check valve closure, pressure rise, pump discharge line, chart.

Transient Behavior of a Cavitating Centrifugal Pump at Rapid Change in Operating Conditions—Part 3: Classifications of Transient Phenomena

1999 ◽  
Vol 121 (4) ◽  
pp. 857-865 ◽  
Author(s):  
T. Tanaka ◽  
H. Tsukamoto
Keyword(s):  
Water Column ◽  
Centrifugal Pump ◽  
Rapid Change ◽  
Transient Behavior ◽  
Operating Conditions ◽  
Critical Conditions ◽  
Pump System ◽  
Column Separation ◽  
Cavitation Bubbles ◽  
Flow Mechanisms

Analytical studies were developed on the transient behavior of a cavitating centrifugal pump during the transient operations, including the sudden opening/closure of the discharge valve and the pump startup/shutdown. In order to investigate the mechanism of the low cycle oscillations of both the pressure and the flowrate at a rapid change of the pump system conditions, an unsteady flow analysis was made for the cavitating pump-system by assuming the transient pump performance to be quasi-steady. The calculated unsteady pressure and flowrate during the transient period agree with the corresponding measured time histories. It is shown that the fluctuations of delivery pressure and discharge flowrate at pump rapid startup or sudden valve opening are caused by peculiar oscillating cavitation dynamics inside the pump at rapid increase in flowrate, while the fluctuations at pump rapid shutdown or sudden valve closure are related to the collapse of cavitation bubbles or water column separation in the suction pipe at rapid decrease in flowrate. Moreover, the occurrence of transient fluctuations in pressure and flowrate was predicted by examining the critical condition which creates the occurrence of two different flow mechanisms i.e., (A) oscillating cavitation and (B) water column separation including also the collapse of the cavitation bubbles. These flow mechanisms were represented with two flow models i.e., (A) unsteady cavitating flow incorporating effects of cavitation compliance and mass flow gain factor and expressed by a set of ordinary differential equations solved with the Cardano Method and (B) water-hammer type model including Discrete Free Gas Model and solved with method of characteristics. The calculated critical conditions for the occurrence of the oscillating cavitation and water column separation agree qualitatively with measured ones.

A Lagrangian wave characteristic method for simulating transient water column separation

2009 ◽  
Vol 101 (6) ◽  
pp. 64-73 ◽  
Author(s):  
Bong Seog Jung ◽  
Paul F. Boulos ◽  
Don J. Wood ◽  
Christopher M. Bros
Keyword(s):  
Water Column ◽  
Characteristic Method ◽  
Wave Characteristic ◽  
Column Separation

Water-Column Separation at Two Pumping Plants

1968 ◽  
Vol 90 (4) ◽  
pp. 521-530 ◽  
Author(s):  
R. J. Brown
Keyword(s):  
Water Column ◽  
Detrimental Effect ◽  
Time History ◽  
Field Measurements ◽  
Measured Data ◽  
Operating Characteristics ◽  
Inherent Difficulty ◽  
Column Separation ◽  
History Of ◽  
Entrained Air

Results of field measurement of transients in two pump discharge lines show that the pressures were greater than had been predicted during design, and a theory and method of analysis are developed which explains the time-history of the transients measured. The field measurements were undertaken because of the complexity of the phenomena and because very little measured data were available. Results are presented graphically along with analytical solutions. Conclusions drawn were: (a) The inherent difficulty of prediction of water-column separation effects is further complicated by the uncertainty about complete pump operating characteristics and actual moment of inertia of pumps and motors; (b) the effects of air and gases entrained in solution in the water must be considered in the analytical solution; and (c) entrained air can have a detrimental effect on the water-hammer transient, i.e., larger pressure surges in the discharge line and higher reverse speeds of the pumps can be caused by its presence.

A Large-Volume Pump System for Studies of the Vertical Distribution of Fish Larvae Under Open Sea Conditions

1986 ◽  
Vol 66 (4) ◽  
pp. 845-854 ◽  
Author(s):  
R. P. Harris ◽  
L. Fortier ◽  
R. K. Young
Keyword(s):  
Water Column ◽  
Large Volume ◽  
Larval Fish ◽  
Fish Larvae ◽  
Physical Structure ◽  
Small Scale ◽  
Fine Scale ◽  
Pump System ◽  
Open Sea ◽  
Temporal And Spatial

A large-volume pump system (2.8 m3 min-1) for sampling fish larvae under open-sea conditions is described. Comparative efficiency trials by day and night showed that the pump was generally as efficient, or in some cases more efficient, in capturing larvae than vertically hauled 200 μm WP2 nets, though there was some evidence of visual avoidance by particular larval size classes during daylight. The pump system is particularly appropriate for investigating fine-scale vertical aggregations (1–10 m3) of larval fish in relation to the distribution of their food organisms.INTRODUCTIONStudies of the distribution of larval fish and their food organisms in relation to physical structure in the water column require sampling techniques capable of resolving fine-scale temporal and spatial distributions. As an alternative to conventional nets, large-volume pumps, sampling at rates in excess of 1 m3 min-1; provide such a capability. Major benefits of using large pumps in addition to temporal and spatial resolution are that a wide range of sizes of plankton including larval fish can be sampled simultaneously in relation to physical and chemical properties of the water column; there is reliable control of the volume of sample filtered and problems of clogging of towed nets are avoided; long series of sequential samples can be taken in studies of small-scale distribution; and instrumentation with in situ CTD and fluorometers at the intake enables real-time control of sampling in relation to physical structure.General engineering considerations for using such pumps have been reviewed in detail by Miller & Judkins (1981), and a particular area of application has been in power-plant entrainment studies in shallow fresh water (Portner & Rhode, 1977; Bowles & Merriner, 1978; Gale & Mohr, 1978; Ney & Schumacher, 1978; Elder et al. 1979; Leithiser, Ehrlich & Thum, 1979; Cada & Loar, 1982).

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.

Pressure Surges Following Water-Column Separation

1961 ◽  
Vol 83 (3) ◽  
pp. 456-458 ◽  
Author(s):  
J. T. Kephart ◽  
Kenneth Davis
Keyword(s):  
Water Column ◽  
Rapid Assessment ◽  
Column Separation ◽  
Water Columns ◽  
Pressure Surge

Equations have been derived using rigid-water-column theory which permit rapid assessment of pressure surge magnitude owing to rejoinder of water columns in pump-discharge lines subsequent to a water-column separation induced by failure of power to the pump drivers. The method is valid only for systems which are equipped with check valves at the pumps.

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