The effect of the blended blade and end wall three-dimensional profiling design on cascade

Abstract

Blended Blade and End Wall (BBEW), a passive control method, has been employed in the turbomachinery field and verified to improve compressor performance effectively. In this paper, a new profiling method, based on suction surface parameterization, is proposed to enhance the flexibility and three-dimensional characteristics of BBEW profiling. The new profiling method is applied to a high subsonic-speed and highly loaded compressor cascade. The aim is to investigate effective flow control rules and practical design guidelines under multi-operating conditions. First, the design method for the experiential formula is established, and the relationship between the profiling control mechanism and the profiling geometry feature is investigated in the entire three-dimensional design space. Then, comparing different radian pattern profilings on design and stall conditions, a series of quantitative analyses and flow field analyses are conducted to discuss flow control mechanism. The numerical results verify that the three-dimensional BBEW design brings a more positive effect on corner separation. The primary flow control rule is enhancing the driving force at the blade root, which can effectively increase the kinetic energy of the low-energy fluid in the corner region and reduce loss. However, design and stall conditions also have specific differences in the mechanism of loss reduction. It mainly focuses on the aggravation of mixing loss when the low-energy fluid obtains more kinetic energy on design condition, but the problem hardly exists in stall condition. Thus, a larger radian pattern is beneficial to controlling the flow on design condition, but the stall condition is the opposite.