Impact Evaluation of Full-Span Slot and Blade-End Slot on Performance of a Large Camber Compressor Cascade

It has been proved that suitable slot structure of compressor slotted blade can generate high-momentum jet flow through pressure difference between the pressure and suction surface, the slot jet flow can reenergize the local low-momentum fluid to effectively eliminate the flow separation. In order to investigate and evaluate the impact of full-span slot and blade-end slot on the performance of the post-loaded blade, which has serious flow separation on the suction surface both near blade midspan and endwall, a diffusion stator cascade with large camber angle is selected as the research object. Firstly, the blade-end slotted scheme and the full-span slotted scheme are set up. Then the performance of datum cascade and two slotted cascades is computed in the wide incidence angle range of -8º to 6º at the Mach number of 0.7, the corresponding blade-chord-based Reynolds number Re_c is 7.7×10⁵. Finally, the performance of the three cascades is analyzed and compared. The results show that, in the computational incidence angle range, both of the two slotted schemes can reduce the total pressure loss for datum cascade and enhance its pressure diffusing capability. However, compared with the blade-end slot, the full-span slot has a better comprehensive control effect on the corner separation and the boundary layer separation near blade midspan, hence, compared with those of blade-end slotted cascade, the total pressure loss coefficients and the static pressure coefficients of full-span slotted cascade are respectively further decreased and increased. Under the blowing effect of full-span slot jet, the total pressure loss coefficients of datum cascade are significantly decreased, ranging as high as 21.2%, 23.1%, 24.5% and 23.4% under the incidence angles of 0°, 2°, 4° and 6°, respectively. The full-span slotted scheme has a better adaptability to wide incidence angle range, it can effectively broaden the available incidence angle range for datum cascade.