To develop a high efficiency volute pump in the very low n s range, two kinds of test results at n s =60 are summarized, the optimization of impeller using 11 impellers and the optimization of volute casing changing volute design parameters are done, and new test is added to reveal the flow interference between inpeller and volute tongue.

Influence of rock resistance and temperature difference on the spiral casing structure of large-sized hydropower station;

Theory study on reinforcing steel bar for spiral case structure in high head pumped-storage station;

In the nonlinear computation of the spiral case structure of Three Gorge Power Station,damage mechanics is introduced to study the concrete cracks from microcosmic to macrocosmic scope.

It is confirmed that crack width restriction should be the requirement for the reinforcement of spiral case structure.