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Condensation Induced Water-Hammer, CIWH, has been an historical problem for the nuclear power industry over the past 2 decades. It has caused damage to plant systems, and considerable anguish to plant operators. This thesis has embarked on an attempt to characterize the fluid motion, heat transfer, mixing, and stability of a horizontal, stratified flow of steam over subcooled water. A literature review was conducted to determine the state of numerical and analytical methods which have been applied to this problem. The result of the review has led to the implementation of new analytical interfacial stability models. Information from the review has also led to the development of correlations for wave frequency and amplitude on the phase interface. A numerical model has been developed to estimate the temperature profile on the phase interface. Also, the model will construct, by use of the above correlations, an estimate of the interface wave structure. This wave structure is then evaluated against a non-linear model for interface stability to determine the onset of slug formation. The numerical model has been used to evaluate two known CIWH events. The results indicate that the onset of slug formation is necessary, but not sufficient, to ensure a water-hammer event. The results imply that there is the possibility that once a slug has formed, it may break up before a trapped steam void can fully collapse. The model also indicates that CIWH in steam generator, feedwater nozzle sections is not due to the formation of slug on an unstable phase interface. Rather, CIWH may occur when the liquid level inside of the feedwater nozzle is above the top of the feedring, thus creating an isolated steam pocket. The rapid condensation of the trapped steam in the causes CIWH. This particular result implies that it may be possible to completely avoid CIWH in the feedwater nozzle altogether. / Graduation date: 1991

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The transient flow in pipe networks is represented by a pair of quasi-linear hyperbolic partial differential equations. The method of characteristics is used to transform these equations to a set of ordinary differential equations, which are then solved, by a first order finite difference technique using suitable boundary conditions. The main purposes of these investigations are: 1) To derive suitable boundary conditions or boundary condition equations for valves, sprinklers, surge tanks and air chambers, and 2) To investigate the effect of these boundary conditions on the transient flow in pipe systems. Several numerical examples are solved on the digital computer using the method of characteristics. The results are compared with those obtained by the graphical method. Although in this thesis the developed boundary conditions are used to study the transient response of the irrigation pipe systems, the boundary conditions, without any modification, can be used to determine the transient conditions in water supply pipe networks or in pipes carrying other liquids. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

This thesis provides a comprehensive look at water hammer with an emphasis on home plumbing systems. The mathematics of water hammer are explained, including the momentum and continuity equations for conduits, system construction, and the four-point implicit finite difference scheme to numerically solve the problem. This paper also shows how the unsteady momentum and continuity equations can be used to solve water distribution problems instead of the steady-state energy and continuity equations, along with the examples problems which show that an unsteady approach is more suitable than the standard Hardy-Cross method. Residential plumbing systems are examined in this paper, household fixtures are modeled for their hydraulic functions, and several water hammer simulations are run using the Water Hammer and Mass Oscillation program (WHAMO). It is determined from these simulations that the amount of air volume in the system is a key factor in controlling water hammer. Abnormal pump operation is clearly explained including a description of the four quadrants and eight zones of operation as well as the mathematics and a numerical scheme for computation. Low pressures caused by transients can lead to intrusion and contamination of the drinking water supply. Several scenarios are simulated using the WHAMO program and cases are provided in which intrusion occurs. From the intrusion scenarios, key factors for intrusion to occur during transients include the starting energy in the system, the magnitude of the transient, the hydraulics of the intrusion opening, and the external energy on the pipe (the level of the groundwater table). A primer for using WHAMO is provided as an appendix as well. / Master of Science

A new closed-loop frequency-domain model is developed to incorporate the water hammer effect with pump rotordynamics, in order to investigate the sub-synchronous instability problem observed in a field pump. Seal flow-rate perturbations due to eccentricity are calculated from Soulas and San Andres's seal code. A complete transfer function matrix between rotor motion and reaction force due to pressure perturbation is developed in detail. Stability analysis with transfer-function'add-in' modules is conducted in XLTRC2. Seal clearances and the reaction force angle are found to be important in shifting natural frequencies and damping. The sub-synchronous instability observed in field is duplicated successfully with double-clearance seals.

A new closed-loop frequency-domain model is developed to incorporate the water hammer effect with pump rotordynamics, in order to investigate the sub-synchronous instability problem observed in a field pump. Seal flow-rate perturbations due to eccentricity are calculated from Soulas and San Andres's seal code. A complete transfer function matrix between rotor motion and reaction force due to pressure perturbation is developed in detail. Stability analysis with transfer-function'add-in' modules is conducted in XLTRC2. Seal clearances and the reaction force angle are found to be important in shifting natural frequencies and damping. The sub-synchronous instability observed in field is duplicated successfully with double-clearance seals.