Axial Cascade Technology and Application to Flow Path Designs. Part I—Axial Cascade Technology

Abstract

Using established cascade criteria, such as the aerodynamic blade loading coefficient and the blade surface diffusion ratio, generalized relations for the losses in cascades of axial turbomachines are formulated. These relations have been evaluated numerically for incompressible media, assuming conventional Reynolds numbers. The results are presented in forms of diagrams showing profile, endwall, and clearance loss coefficients. The calculated data are compared with test data, revealing fair agreement, with the possible exception of “impulse” cascades. Extension of the “single cascade” data to “multiple row cascades” shows the operating regime where substantial performance improvements can be obtained by multiple row cascades.