Abstract
To investigate the influence of blade-tip height deviations caused by machining errors and overhaul wear on compressor aerodynamic performance, numerical simulations are performed on the transonic axial compressor NASA Rotor 37. With a fixed average tip clearance, ten circumferentially non-uniform tip clearance cases are designed and classified into three categories: globally reduced clearance, globally increased clearance, and mixed clearance variation. The results reveal that the circumferential distribution direction of non-uniform tip clearance has a remarkable impact on both the compressor stability margin and aerodynamic efficiency. The clearance distribution pattern that decreases gradually against the rotor rotation direction outperforms the increasing pattern in terms of both aerodynamic performance and stability margin. For the mixed clearance cases with the same average clearance as the baseline compressor, the scheme with clearance decreasing against the rotation direction achieves a 0.24% higher peak efficiency than the baseline, with nearly unchanged stability margin. Unlike casing-deformation-induced non-uniform clearance, this work targets tip-height inconsistency from manufacturing and overhaul. Internal flow analysis indicates that the compressor stability margin is governed by the blade passage with the maximum flow blockage. The abrupt deceleration of leakage flow propagating from a large-clearance sector to an adjacent small-clearance sector is the primary cause of aggravated local blockage and stall onset. This work provides numerical guidance for blade assembly sequencing of transonic axial compressors.