Use of Blended Blade and End Wall method in compressor cascades: Definition and mechanism comparisons

Abstract

Modern turbomachinery design uses the endwall treatment method to prevent the corner flow from separating. This study presents the Blended Blade and End Wall (BBEW) method, a passive endwall treatment method, and draws the distinction between the flow mechanisms of BBEW and fillet cascades.The first part of the study conducts an experimental investigation on the flow mechanism of a BBEW cascade. The results show that BBEW technology can stretch the spanwise area of vortices, thus reducing losses at a lower spanwise position, slightly increasing losses at a higher position, and improving the corner separation.In the second part of the study, comparisons of the flow mechanisms of the BBEW and fillet cascades are conducted using numerical methods. The results show that the fillet cascades induce a pressure difference at nearly the full range of the chord. BBEW cascade induces a pressure difference at a certain chordwise position, and the magnitude of the pressure difference is larger. The pressure difference tends to move the low-energy fluid away from the corner and reduce the cross flow accumulation, which reduces the endwall losses.