The Blended Blade and Endwall(BBEW)technique has proven to be effective in control-ling the intersection of boundary layer in corner region of the compressor endwall.In this study,the experiment and analysis of two di...The Blended Blade and Endwall(BBEW)technique has proven to be effective in control-ling the intersection of boundary layer in corner region of the compressor endwall.In this study,the experiment and analysis of two different BBEW designs are emphasized.First,based on a linear cas-cade with 0.7 Mach number inflow,two different configurations,BBEW 1 and BBEW 2,are well conducted.Then,according to the experimental result,control effects of these two BBEW configu-rations are validated and compared subsequently under various working conditions.The results demonstrate a reduction in total pressure loss of 12.8%and 29%at the design point for BBEW 1 and BBEW 2,respectively.Consequently,the BBEW technique proves effective in suppressing the development of the boundary layer and preventing corner separation.Followed by detailed numerical analysis,improvements around the corner region,especially for the boundary layer,are extracted to show the mechanisms and distinctions between the two configurations.The results indicate that BBEW 1 significantly restrains the development of boundary layer before separation occurs,while BBEW 2 directly controls the strength and scale of the corner separation.展开更多
In the current state-of-the-art,high-loss flow in the endwall significantly influences compressor performance.Therefore,the control of endwall corner separation in compressor blade rows is important to consider.Based ...In the current state-of-the-art,high-loss flow in the endwall significantly influences compressor performance.Therefore,the control of endwall corner separation in compressor blade rows is important to consider.Based on the previous research of the Blended Blade and End Wall(BBEW)technique,which can significantly reduce corner separation,in combination with a nonaxisymmetric endwall,the full-BBEW technique is proposed in this study to further reduce the separation in endwall region.The principle of the unchanged axial passage area is considered to derive the geometric method for this technique.Three models are further classified based on different geometric characteristics of this technique:the BBEW model,Inclining-Only End Wall(IOEW)model,and full-BBEW model.The most effective design of each model is then found by performing several optimizations at the design point and related numerical investigations over the entire operational conditions.Compared with the prototype,the total pressure loss coefficient decreases by 7%–9%in the optimized full-BBEW at the design point.Moreover,the aerodynamic blockage coefficient over the entire operational range decreases more than the other models,which shows its positive effect for diffusion.This approach has a larger decrease at negative incidence angles where the intersection of the boundary layer plays an important role in corner separation.The analysis shows that the blended blade profile enlarges the dihedral angle and creates a span-wise pressure gradient to move low momentum fluid towards the mainstream.Furthermore,the inclining hub geometry accelerates the accumulated flow in the corner downstream by increasing the pressure gradient.Overall,though losses in the mainstream grow,especially for large incidences,the full-BBEW technique effectively reduces the separation in corners.展开更多
基金the National Major Science and Technology Project of China (No.2019-II-0003-0023).
文摘The Blended Blade and Endwall(BBEW)technique has proven to be effective in control-ling the intersection of boundary layer in corner region of the compressor endwall.In this study,the experiment and analysis of two different BBEW designs are emphasized.First,based on a linear cas-cade with 0.7 Mach number inflow,two different configurations,BBEW 1 and BBEW 2,are well conducted.Then,according to the experimental result,control effects of these two BBEW configu-rations are validated and compared subsequently under various working conditions.The results demonstrate a reduction in total pressure loss of 12.8%and 29%at the design point for BBEW 1 and BBEW 2,respectively.Consequently,the BBEW technique proves effective in suppressing the development of the boundary layer and preventing corner separation.Followed by detailed numerical analysis,improvements around the corner region,especially for the boundary layer,are extracted to show the mechanisms and distinctions between the two configurations.The results indicate that BBEW 1 significantly restrains the development of boundary layer before separation occurs,while BBEW 2 directly controls the strength and scale of the corner separation.
基金sponsored by the National Natural Science Foundation of China(Nos.51676015 and 51976010)National Major Science and Technology Project of China(Nos.2017-II0006-0020 and 2017-II-0001-0013)Beijing Institute of Technology Research Fund Program for Young Scholars,China。
文摘In the current state-of-the-art,high-loss flow in the endwall significantly influences compressor performance.Therefore,the control of endwall corner separation in compressor blade rows is important to consider.Based on the previous research of the Blended Blade and End Wall(BBEW)technique,which can significantly reduce corner separation,in combination with a nonaxisymmetric endwall,the full-BBEW technique is proposed in this study to further reduce the separation in endwall region.The principle of the unchanged axial passage area is considered to derive the geometric method for this technique.Three models are further classified based on different geometric characteristics of this technique:the BBEW model,Inclining-Only End Wall(IOEW)model,and full-BBEW model.The most effective design of each model is then found by performing several optimizations at the design point and related numerical investigations over the entire operational conditions.Compared with the prototype,the total pressure loss coefficient decreases by 7%–9%in the optimized full-BBEW at the design point.Moreover,the aerodynamic blockage coefficient over the entire operational range decreases more than the other models,which shows its positive effect for diffusion.This approach has a larger decrease at negative incidence angles where the intersection of the boundary layer plays an important role in corner separation.The analysis shows that the blended blade profile enlarges the dihedral angle and creates a span-wise pressure gradient to move low momentum fluid towards the mainstream.Furthermore,the inclining hub geometry accelerates the accumulated flow in the corner downstream by increasing the pressure gradient.Overall,though losses in the mainstream grow,especially for large incidences,the full-BBEW technique effectively reduces the separation in corners.
