History of Water-Hammer

Water-hammer is the phenomenon of the transmission of pressure and velocity surges along a pipe or conduit when a change in either the velocity or the pressure is imposed at some section in the pipe or at its ends. This change maybe imposed by some mechanical device such as a valve or by a variation in the performance of some hydraulic machinery attached to the pipe, such as a pump or hydraulic turbine. This report traces the theoretical development of the phenomenon of water-hammer from the days of the natural scientists of the seventeenth century to the middle of the twentieth century. In the larger field of hydraulics, early development was based on problems of transportation of water, and on the measurement of flow for irrigation and for domestic use in the centres of population. This involved devices for pumping, for delivery along canals and conduits, and for the measurement of quantities used by individuals. The theory and designs had to do with hydrostatic pressures, friction losses, and discharge coefficients, most of which could be handled by experimental studies. There was no need to consider cases of unsteady flow, either in open channels or in closed pipes and conduits. The action of waves on shore lines, in bays and ports, and along canals, was the only problem similar to water-hammer known in early times, and the mathematical and physical knowledge in those days was unable to cope with this problem except by construction of breakwaters for protection of harbours and shipping. This branch of hydraulics, now designated as coastal engineering, which deals with tidal and surface waves, has become a very important field, particularly in this 20th century