Numerical simulation was carried out to study the influences of blade-bowing designs based on a highly loaded cascade with large turning angle, while the compound bowing design showed much lower endwall loss than the conventional design in this study. Generally, it showed that the increased turning angle would strengthen the adverse pressure gradient on the suction surface, so the side effect of negative blade bowing angle would be enhanced because of the reduced flow filed stability near suction–endwall corner. However, the positive corner bowing angle that applied in the compound bowing design would enhance the flow field stability near the suction–endwall corner by adjusting spanwise pressure gradient and velocity triangle, so the side effect of negative blade bowing angle would be suppressed and lead to weaker secondary flow. In detail, the blade bowing angle (as well as the corner bowing angle in the conventional bowed cascades) was varied from −5° to −30° in this study, while the reductions of the loss coefficient in the compound bowed cascades were about 0.662.16 times higher (the absolute differences were about 0.0067 0.0097) than the corresponding conventional bowed cascades. Moreover, the Reynolds number and Mach number at the outlet plane were kept at 2.4 × 105 and 0.6, respectively, during the bowing design to ensure the comparability.
The pitch-wise uniformity of inlet flow was proved by experiment in low-speed plane cascade, and simulations were performed for investigation and improvement in this study after that. The deflector, which was connected to the blade strictly, was proved to be the cause of the problem according to the simulation, and unexpected inflection of inlet flow were proved at the same time. It was also proved that a gap, which was placed between the blade and the deflector, could weaken the influence of deflector. However, the leakage that caused by the gap would also lead to some negative effects that attentions must be paid to. Finally, with cascade moved half-pitch along x-axis and one extra blade added, more acceptable result between 1 and 4 relative pitch-wise was showed in one of the improved cases (Case B). Better inlet condition with more periodic pressure distribution and acceptable incident angle were gained.
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