[Objective] Large‑capacity multi‑stage steam axial compressors used in mechanical vapor recompression(MVR) systems operate under high temperature-rise conditions

under which severe hub corner separation is prone to occur in the stator hub annulus wall region. The associated secondary flow structures concentrate aerodynamic losses

deteriorate stage efficiency and thus reduce the overall efficiency of the compressor. This study aims to address the performance degradation caused by hub corner separation in such machines and to evaluate the effectiveness of bowed stator blades in mitigating annulus wall losses while maintaining the required overall total pressure ratio. [Methods] A five-stage steam axial compressor serving a typical industrial MVR system is selected as the research object. On the basis of the baseline design

appropriate positive circumferential bow angles are applied to the stator blades of each stage to form a bowed-stator configuration

while the original straight-stator arrangement is retained as the reference case. A validated three-dimensional steady Reynolds-averaged NavierStokes numerical method

together with suitable turbulence modelling is employed to carry out CFD simulations for both configurations. The calculations are performed under the design operating condition

and the overall performance parameters as well as detailed flow-field data are obtained for comparative analysis. [Results] The numerical results show that

with the bowed‑stator design

the overall total pressure ratio of the compressor at the design point is essentially unchanged and still satisfies the MVR process requirement. Under this constraint

the overall efficiency of the bowed‑stator configuration is increased by 6.1% compared with the straight‑stator baseline. Stage‑wise performance analysis indicates that both pressure ratio and stage efficiency are generally improved for the middle stages when bowed stators are adopted. Flow‑field analysis further reveals that the bowed blades modify the radial distribution of blade‑surface aerodynamic loading and transfer part of the high loading originally concentrated near the annulus wall region towards the more efficient mid‑span region. At the same time

the annulus wall loading gradient is beneficially adjusted

which weakens the reverse helical motion and the intensity of secondary flows in the hub corner region

leading to smoother and more uniform flow near the hub annulus wall and a significant reduction in annulus wall losses. [Conclusion] Appropriately designed positively bowed stator blades can effectively alleviate hub corner separation in large multi‑stage steam axial compressors

reduce annulus wall losses

and improve the overall isentropic efficiency while maintaining the total pressure ratio of the baseline scheme and enhancing the stable operating characteristics. The present work provides a useful reference for bowed‑stator design and performance improvement of multi‑stage steam axial compressors employed in MVR systems.