Investigation of Leading Edge Tubercles with Different Wavelengths in an Annular Compressor Cascade

Abstract

Abstract Humpback whales possess bumpy tubercles on the leading edge of their flippers. Due to these leading edge tubercles, whales are able to produce high degree of maneuverability. Inspired by the flippers, this paper applies sinusoidal-like tubercles to the leading edge of blades in an annular compressor cascade, and presents a numerical investigation to explore the effects of tubercles with the aim of controlling the corner separation and reducing losses. Steady 3D RANS simulations are performed to investigate the aerodynamic performance and behavior of the corner separation in compressor cascades with and without leading edge tubercles. A crucial geometry parameter of the tubercles, wavelength, is varied to obtain different configurations. Results show that a smaller wavelength (more wave number) corresponds to a larger loss reduction and the maximum loss reduction reaches to 46.0%. Also, it is found that leading edge tubercles result in a stall delay and the maximum stall angle improvement reaches to 28.1%. Flow visualizations show that leading edge tubercles could induce the formation of counter-rotating streamwise vortices. The interaction between the streamwise vortices and corner separation is thought to be the primary flow mechanism generated by leading edge tubercles in an annular compressor cascade.