Research on variation mechanism of three-dimensional blade tip clearance of aero-engine

Abstract

Turbine blade tip clearance of aero-engine is of great significance for its efficiency, fuel consumption, running state and detection of faults. Previous researches on operation state monitoring and faults diagnosis of aero-engine turbine vane based on the measurement of blade tip clearance only focused on one-dimensional blade tip radial clearance. But the turbine blade tip clearance manifested as parameters with three-dimensional space characteristics when faults occurred. One-dimensional blade tip radial clearance couldn't fully reflect the faults information. Three-dimensional blade tip clearance is proposed in this work. A simplified three-dimensional rotational symmetric finite element model of a blisk was established to simulate and analyze the three-dimensional characteristic parameters of the vane tip clearance under loads such as centrifugal force, thermal stress and pneumatic pressure. A crack was added to the model, and the variation feature of the three-dimensional blade tip clearance of the model with typical faults was researched. Results show that the uneven blade deformation under various loads leads to variation of the three-dimensional blade tip clearance; axial offset, circumferential offset and torsion appear on the turbine blade tip surface. Compared with the blade radial clearance, the three-dimensional blade tip clearance of the blade can reflect faults information more clearly and accurately.