Experimental And Numerical Investigations On The Aerodynamic Characters Of Turbine Cascades With Curved Blades And A Single-Stage Axial Fan With Meridional Acceleration

Experimental and numerical investigations are carried out on the three-dimensional flow fields in a classical turbine stator cascade with curved blades and a single-stage axial fan with meridional acceleration. The experiments are done in the linear cascade wind tunnel and the axial fan rig, respectively, in Institute of Engineering Thermophysics, Chinese Academy of Sciences. The numerical simulations are conducted by three-dimensional viscous software Fine/Turbo. This thesis is composed of two parts:Part I presents the experimental and numerical results of the effects of blade curving on the flow fields in a classical turbine stator cascade with low aspect ratio. The outlet flow fields and static pressure on blade surfaces of six sets of cascades with different spanwise curving angles, -10\, -20\, 0\(straight), +10\, +20\ and +30\, are measured in details. The three-dimensional viscous flow fields of six sets of cascades are numerically simulated.! On the base of detailed comparisons of outlet flow fields and static pressure distributions between experimental and numerical results, the effects of blade curving on secondary flow, losses, static pressure on blade surfaces, load of blades, flow structure near endwall, vortices are analyzed. The experimental and numerical results consistently show that, the performance of cascades flow fields are not improved by blade curving although the "C" shape distribution of static pressure on blade surfaces is obtained. When the positive curving angle increases, the total losses of cascades increase, the outlet flow angles vary acutely along the spanwise, the intensity and size of outlet trailing vortex increase obviously, however the intensity and scale of outlet passage vortex vary slightly, secondary flow at both midspan and endwall increase and the total averaged kinetic energy of secondary flow increases. . For the turbine stator cascade, the negative curving of blade can not improve the performance of the cascades as well, the total losses of straight cascade are the lowest.Part n presents the experimental and numerical results of a single-stage axial fan with meridional acceleration. The performance parameters at the design speed are measured in the experiments. 11 cases with different geometry models, different inlet conditions and different flow rate are numerically simulated. The influences of hub leakage and inlet boundary layer on the performance and flow fields of the fan are analyzed in details. The results show that the performance of numerical model with inlet boundary layer and without hub leakage is most close to design parameters and the performance of numerical model with inlet boundary layer and with hub leakage is most close to experimental results.