Numerical simulation was performed to investigate the tip clearance flow structures in ultra-highly load turbine cascades. Flow details of leakage vortex

tip separation vortex and upper passage vortex were analyzed

then on this basis

the effects of clearance height on flow characteristics and blade loads were analyzed. Results show that

there are several forms of flow separation in tip clearance region of ultra-highly load turbine cascades

leakage flow is very strong

which not only affects the formation and development of upper passage vortex directly and makes passage vortexes move to blade root

but also causes some of leakage flow to enter into the lower passage vortex. As clearance height increases

tip separation vortex and leakage vortex get stronger

blade load especially tip load decreases.