Axial Compressor Performance Restoration by Blade Profile Control

Abstract

One major source of increased compressor losses is imperfection in blade shape. These imperfections exist for new blades, and as an engine wears in service, the blade shapes become further distorted due to erosion. These imperfections cause an aerodynamic performance penalty in the form of decreased engine capability and increased fuel consumption. A simple numerical blade element panel method, combined with a integral boundary layer technique, has been used to make an aerodynamic analysis of the effect of imperfections in blade shape for compressor blading. This analysis indicated what blade shapes would give increased profile losses, and what kind of reshaping allows restoration of nominal performance. The results of this study were tested by a series of engine cell tests with JT8D engines. These tests indicate that new or used blades that have been sorted, properly re-shaped, and matched allow a superior recovery of performance compared with traditional blade refurbishment practices.