This paper presents the results of a comparative experimental investigation of two turbine test cases with different second stage stator count. The objective is to investigate the possibility of reducing the product cost and weights by reducing stator count while improving overall turbine performance. The experiment was performed in a two-stage axial research turbine facility. The blade geometries under investigations are of typical of the high-pressure section of steam-turbines and the blade rows except the second stage stator are identical between the two test cases. The low solidity stator has 3/4 blades count of the high solidity stator while keeping the same axial chord length. Unsteady and steady data were obtained using the fast response probe and the miniature pneumatic probes at the exit of the first rotor, at the exit of the second stator and the second rotor. The prime interest is focused on the way that performance is changed by the different number of wakes and vortices transporting through the downstream blade rows. In the reduced blade count case, the unsteady flow interactions causes the larger distributions of all flow properties measured. A marked difference is observed near 10 to 35% span where the hub passage vortex is dominant. In the low solidity stator case, the time dependent vorticity variation was found to be 40% larger compared to the high solidity stator case. In correspondence to the vorticity variation, the loss coefficient also varies depending on time. Pneumatic measurements show that the difference of second rotor loss coefficient between the cases is within 1.5% except the tip area. However, unsteady loss variation differs between the test cases depending on the change of the flow structures. The mechanism of this unsteady loss variation is analyzed in detail.

This content is only available via PDF.
You do not currently have access to this content.