Influence of a Wavy Blade-End Applied in an Axial Compressor Cascade on the Secondary Flow of the Passage

Abstract

To improve the compressor performances at variable conditions, in this research, we used numerical simulation software to analyze and discuss the effects of three kinks of a wavy blade-end on an axial compressor cascade. One of the wavy blade-ends was a traditional structure with a wavy leading edge and a trailing edge (WBE_P). The other two wavy blades were new structures with a straight trailing edge and a wavy leading edge (WBE_R, WBE_S). The difference between WBE_R and WBE_S was that the blade profile used to form the wavy blade was different. For WBE_R, we obtained the wavy leading edge by rotating the element at different heights, and the trailing edge was the center of a circle. For WBE_S, we obtained the wavy leading edge by using a new element with a different camber angle. Because of the new geometry involving some discussions of a variety of parameters, we further discussed the geometric parameters and structure to guide the design and optimization of the blade. We drew some conclusions at the stable condition (6° incidence). For the first case (WBE_P), when the wavelength of the wavy blade-end was increased to 0.3 times the blade height, the total pressure loss was enhanced. When the wavelength was 0.2 times the blade height, the amplitude was 0.06 times the pitch, the minimum area of blocked range (Ab) and the total pressure loss coefficient ζ could be obtained, and the ζ and Ab were decreased by 5.49%, and 12.72% compared with the baseline. Furthermore, to weaken the influence of changed blade profile on the exit airflow angle, we proposed WBE_P and WBE_R with new structures. We further improved the flow-field characteristics of WBE_P by WBE_R, and the ζ and Ab decreased by 5.84% and 13.79% compared with the baseline. Additionally, the stall point was delayed from 7.5° to 7.7° incidence. Therefore, the wavy blade-end applied in the leading edge had a greater contribution to improving the flow characteristic, and the straight trailing edge was beneficial to maintaining the exit flow angle. WBE_S with a smoother blade surface did not show an advantage compared with WBE_R. WBE_R with a wavy blade-end leading edge and a straight trailing edge showed an advantage in improving the cascade performance, which was suitable for use in the stator from the last stage of a high-load axial compressor.

Keywords

• wavy blade-end
• corner separation
• axial compressor cascade
• secondary flow
• flow control