Multistage Turbine Simulations With Vortex-Blade Interaction

The average passage approach of Adamczyk et al (1990) has been used to simulate the multistage environment of the General Electric E³ low pressure turbine. Four configurations have been analyzed and compared to test data. These include the nozzle only, the first stage, the first stage and a half and the first two stages. A high casing slope on the first stage nozzle causes the secondary flow vortex to separate off the casing and enter the downstream rotor. The detrimental effect on performance due to this vortex interaction has been predicted by the above approach whereas isolated blade row calculations cannot simulate this interaction. The unsteady analysis developed by Chen et al (1994) has also been run to understand the unsteady flow field in the first stage rotor and compare with the average passage model and test data. Comparisons of both the steady and unsteady analyses with data are generally good, although in the region near the casing of the shrouded rotors, the predicted loss is lower than that shown by the data.