Present Trends in Surge Tank Design

Abstract

The author summarizes the well-known theory of surges in surge tanks, dealing chiefly with the fundamental equations and introducing some preliminary remarks on the stability of surges. He then describes the different types of surge tanks, ordinary cylindrical tanks, tanks with variable section and expansion or reservoir chambers, tanks with restricted orifices, and differential surge tanks, with special mention of surge tanks in conjunction with underground power stations. The loading conditions to be adopted are discussed and the reason why load changes on the electrical grid are the prime cause of surges is explained. The basic assumptions adopted for surge calculations by Italian, Swiss, French, and British engineers are reviewed, and it is shown that, in spite of many apparent disparitiés on special points, there is widespread agreement on fundamental questions. The interaction of surges, water hammer, and turbine governing is discussed in the light of the most recent tests on large power stations and of the results of modern theories, and the importance of the influence of water hammer on surge tank design is considered together with the special case of surge tanks connected to feeder canals.