Highly Loaded Bifurcation Blade Design Methodology And Its Numerical Research On Aerodynamic Performance

On the flow instability problem caused by large scale flow separation in highly loaded compressor/fan cascade passage, a novel bifurcate compressor stator cascade has been designed according to pressure gradient control idea in cascade flow field. A novel variable solidity bifurcate blade concept and three-dimensional blade design technology have been integrated to achieve this design idea. Different models of low/high mach numbers are discussed to further verify the design methodology. Under high Mach number(Ma=0.72), when i=2o,5o,8o, the gain of total-pressure loss co-efficient is reduced by 11.79%, 15.39%, and 15.37%, respectively.The quantitative information of the flow field in the bifurcate cascade is obtained by numerical simulation method to investigate the separation flow structure and dynamic mechanism near wall and in wake area. Besides, applying the vortex dynamics theory, the complex influence of vortex structure evolution and the dynamic mechanism of low energy fluid redistribution control in boundary layer would be revealed. The law of design parameters has been explored in order to decrease aerodynamic loss, delay flow separation near wall/ corner of the cascade, restructure blade aerodynamic load, form smooth pressure gradient and diminish wake flow loss.The results indicate that although extra aerodynamic loss is inevitably generated by the geometric mutation of bifurcate section, the bifurcate blade effectively restrain the migration of high-entropy secondary flow in the shroud corner, thus substantially decrease the loss near endwall/ corner. This mechanism remarkably enhance the overall aerodynamic performance in comparison with conventional annual cascade. Moreover, the bifurcate blade skillfully remold the pressure gradient on the cascade surface as well as to promote total pressure after cascade.With the introduction of significant physical concepts and flow parameters in vorticity dynamics, the physical root and mechanism of gentle pressure gradient formation, wake flow structure and endwall/ corner separation reduction are further revealed. Moreover, the obvious double-wake characteristics are deeply studied by the discussion of wake feature parameters...