Preliminary Study on Forward Loaded Cascades Designed With Inverse Method for Low Pressure Turbine

Abstract

To reduce the number of the turbine vanes or the solidity as far as possible without increasing energy loss, the preliminary study on so called forward loaded turbine cascades had been done. These new cascades were designed for the typical velocity diagrams of the first and the second stage of a jet engine low pressure turbine. With regard to the design procedures, the improved inverse method based on the channel flow method and also boundary layer analysis technique were employed to optimize the surface velocity distributions, and then, compute the cascade geometry. These forward loaded cascades, and the stage-of-the-art aft loaded conventional ones designed for almost equivalent velocity diagrams had been tested in the High Speed Cascade Wind Tunnel of KHI’s Technical Institute. These forward loaded cascades had shown the lower kinetic energy loss coefficient characteristics and the wider useful incidence ranges over the wider region extended to the high subsonic regime comparing with the aft loaded ones, in spite of its higher loading. In addition to some main parts of the design procedures, theoretical and experimental results are discussed.