Recent research on the flow through turbine blade rows.

Abstract

Recent research on the flow through turbine blade rows covers the following regions : (i) theoretical analyses of inviscid and viscous compressible flow through cascades or turbine stage, (ii) experimental investigations of the cascades and turbine stages, (iii) secondary flow, (iv) unsteady flow, (v) design methods, (vi) wet steam flow, and (vii) special turbines. In this review, research carried out over the past five years was dealt with. As regards the development in computing methods of internal flow, a time-marching method of viscous compressible transonic flow through a stage and an inviscid unsteady flow calculation was explained. As for secondary flow, theoretical analysis has been improved significantly as of late. However, more information on the turbulence structure of blade boundary layers and on the mixing process in the downstream of blade rows and the effect of leading edge vortices are necessary. Unsteady flow in a blade row due to the wake of the upstream blade row can be well described, but the more important unsteady flows in the low pressure stages, caused by non-uniform flow at low flow rate conditions or due to the fluctuation of the shock wave location, remain unsolved.