Steam Bubble Collapse And Water Hammer In Piping Systems

Author : Robert Lawrence Gruel
Publisher :
ISBN 13 :
Total Pages : 81 pages
Book Rating : 4.:/5 (692 download)

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Download or read book Steam Bubble Collapse, Water Hammer and Piping Network Response written by Robert Lawrence Gruel and published by . This book was released on 1980 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction: Conventional and nuclear power steam systems require the transport of high pressure, high temperature steam and water through complex piping networks. During transient phases of operation, steam and subcooled water can be present simultaneously in a variety of piping and reservoir configurations. Under certain conditions, instabilities in the two phase flows can give rise to water hammer events. Most notable are the water hammers experienced in the feed pipes to steam generator spargers in pressurized water nuclear reactors. Little is currently known about the mechanisms involved in the evolution of water hammer. Creare (1977) offers a possible description of how instabilities in the feed water pipe of a PWR steam generator can lead to the formation of an isolated steam bubble between two columns of subcooled water. Under such conditions, the steam inside the bubble rapidly condenses, causing bubble collapse and impact of the two water columns. This leads to the formation of high amplitude pressure waves which propagate through the piping network, causing deflections and possible damage to the pipes and their supports. This study combined with the work done by Gruel (1980) attempts to analyze the events which occur after the formulation Of an isolated steam vapor bubble. Experimental and theoretical models are developed to investigate the condensation process leading to steam bubble collapse, the mechanisms involved in the propagation of pressure waves through pipes, and the resultant fluid-structure interactions. The focus of this study is on experiments run with a small scale water hammer generator (Gruel 1980) which can be used to form an isolated steam bubble between two columns of water under stable conditions. By opening a valve, the steam is brought into contact with cold water. The steam bubble collapses and a water hammer transient results. The subsequent wave propagation and structural interactions can be measured in a length of pipe connected to the water hammer generator. Three theoretical models are developed to help understand three separately defined processes involved in the experiments. The first is a model of the condensation and initial collapse of the steam bubble. Gruel (1980) uses this model in the analysis of data taken for this phase of the study. The second model uses the method of characteristics (Wylie & Streeter 1978) to describe the propagation of pressure waves through the experimental piping network. Finally, a simple deflection model is used to help understand the fluid-structural interactions associated with the water-hammer transient.