ANNALYSIS OF WATER HAMMER IN PIPE NETWORKS

Abstract

The term water hammer describes the effects of unsteady flow of liquids in pipelines. It is accompanied by the rise and fall of pressure from the steady state condition. Therefore,it is necessary to analyse water hammer in a pipe network for economical design. The governing equations for water hammer are equation of continuity and motion. The "method of characteristics" based on Elastic Water Column theory has certain advantages over the other available methods. Attempts have been made since the seventeenth century for the analysis of water hammer. Mange in 1789, introduced "methods of characteristics". Korteweg determined the wave velocity considering the elasticity of both the pipe wall and the fluid. Allievi published the general theory of water hammer in 1902. Oniluka in 1983 analysed slow transients in pipe networks based on Rigid Water Column theory. In the present study an attempt has been made to analyse water hammer in an existing pipe network of the cooling water system of the Raighat thermal power station, New Delhi. The "method of characteristics" has been used. Transients caused due to various operations have been considered. Available computer programs for analysis of transients in single and branch pipe line have been modified to analyse transients in the pipe network. It is concluded from the results obtained that the most vulnerable location for the severe negative pressure is the downstream condenser water box in the pipe network. When a pump trips suddenly the head falls more rapidly than discharge and the pump speed. Transients due to closing of both the valves create rise of pressure and transients due to tripping of both the pumps create fall of pressure in pipe network.