Flow in a Turbine Cascade: Part 1—Losses and Leading-Edge Effects

Abstract

An experimental investigation was conducted to study the effect of the leading-edge shape on the overall losses in a large-scale linear cascade of turbine blades. The leading-edge shapes used were a cylinder and a wedge. The cascade was designed to be geometrically similar to the cascade used by Langston et al. at United Technologies Research Center, with the same span/chord and pitch/chord ratios. Measurements of wall static pressure on the blades and of total pressure and flow direction downstream of the cascade showed only minor changes due to the alteration of the leading-edge shape. The measurements of the flow and loss distributions downstream of the cascade complement the results of Langston et al., which showed the flow development only within the cascade. The downstream flow is important, however, as apppoximately 50 percent of the losses occur downstream of the trailing edge. Regions of high loss were found near midspan at an axial location 40 percent of the axial chord downstream of the trailing edge. The sources of fluid in these regions are determined in Part 2.