Active radial clearance design method based on customized linear expansion coefficient

Abstract

The active clearance control (ACC) technology for compressors in aero engines has slow deformation response, which is not suitable for military aero engines with drastic changes in throttle lever, and leads to the problem of excessive radial tip clearance in the compressors of military aviation engines during cruising. The thought and specific implementation method for the active radial clearance design of aircraft compressor clearance is studied. By utilizing the characteristic that the radial deformation of the compressor casing is mainly determined by thermal loads, the adjustable and positive design of the casing′s radial deformation is achieved by customizing the linear expansion coefficient of the casing. The design method is applied to the clearance design of the third-stage rotor of a certain compressor. The results show that the active radial clearance design method can achieve the design goal of reducing the clearance of the engine in several stable operating conditions such as cruising. Moreover, it is proposed that a larger difference in the linear expansion coefficient of the casing material between cruise conditions and the minimum clearance state is more conducive to reducing the radial tip clearance during cruise, which can provide a reference for casing material selection.

Keywords

• clearance design
• linear expansion coefficient
• casing material selection
• compressor
• multiple loading conditions