Abstract: Considering distortions of the stream surface and through the search for suitable axial velocity distributions in controlled vortex design stage, a 1.5-stage subsonic axial flow turbine is designed by controlled vortex design method with the given pressure distributions to resolve circulation distributions. The turbine blades are then obtained through parameterization design and are numerically studied through 3D viscous simulation finally. The results show that this controlled vortex design method relieves the transverse pressure gradient in cascade passage to keep the low-energy fluid from moving towards the blade suction. Also, it removes the negative pressure gradient along radial direction which could reduce the passage vortex core energy. Compared with free vortex design, the controlled vortex design turbine efficiency is increased by 0.67%, and the power, 3.47%. The results also indicate that the pressure controlled vortex design method not only enhances the stage match but also prevents the blade outlet flow parameters from non-uniform to reduce mixing losses to the greatest extent.

Key words: turbine, turbine design, blade modeling, controlled vortex design, pressure controlled vortex, numerical simulation