Effect of a swirl flow on transient phenomena in a draft tube during a load rejection

T. Nonoshita, Y. Matsumoto, H. Ohashi, T. Kubota, M. Fujita

Research output: Contribution to journalArticle


In water turbines, a swirl flow is generated in a draft tube during a load rejection. Moreover, water turbines tend to be operated at a partial load condition because they bear the role of load followers for electric power network. Under this condition, a swirl flow exists in a draft tube and tailrace before the load rejection. In order to investigate the effect of the swirl flow on the transient phenomena during a load rejection, especially on the water column separation in the draft tube, experiments were conducted using a model turbine. The results revealed the following: The swirl flow promotes a gas release from water due to the increase of the interfacial area between water and vapor, and the released gas affects the transient phenomena. The released gas makes the pressure rise at the rejoin of the separated water column lower and the period of the pressure pulsation longer. The amount of the released gas depends on the initial swirl rate and the dissolved air content in the water. (A)

Original languageEnglish
Journal[No source information available]
Publication statusPublished - 1 Jan 1990


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