Investigation of the impact of distorted intake airflow on cooling fan performance and optimization of forced air-cooling scheme in high-power electric generator

Focusing on a high-power closed-type forced air-cooling electrically excited generator (HCFAEEG), this study investigates the impact of distorted intake airflow—characterized by radial inflow, flow turning, and contraction—on cooling fan performance within the HCFAEEG, and proposes an optimized air-cooling scheme based on the internal airflow path and fan design. The results show that distorted intake airflow significantly impairs the fan’s pressure rise capability and ventilation capacity: the operating flow rate decreases from 1.95 m 3 /s under ideal inlet condition to 1.65 m 3 /s under distorted inlet condition, representing a relative reduction of approximately 15.4%. The reduced airflow leads to excessive temperature rise in the HCFAEEG. To address these issues, a two-pronged optimization strategy is implemented. First, by optimizing the ventilation areas at the outlet and stator back yoke while balancing air resistance and thermal constraints, a more efficient internal airflow structure is achieved. Second, the cooling fan is comprehensively redesigned using a multi-parameter approach that integrates a slant-flow configuration, increased blade solidity, reduced tip clearance, and twisted blade profile. The optimized fan exhibits enhanced pressure generation and improved tolerance to inlet distortion, with the operating flow rate decreasing by only 6.9% under distorted inlet condition compared to ideal inlet condition. Finally, the integrated performance of the fully optimized air-cooling scheme—incorporating both the revised airflow path and the redesigned fan—is evaluated, and the results indicate that the temperature of the generator windings decrease significantly after implementing the optimized air-cooling scheme.