Abstract: Aiming at the stall of axial-flow fan happened regularly in the heavy-duty locomotive， a three-dimensional numerical model was built to study the aerodynamic performance of the axial-flow fan and predict the stall point. The coupling equations of pressure and velocities were solved with the SIMPLE algorithm， and the RNG k-ε turbulence model was also applied to this simulation. The performance parameters under several different conditions were calculated， and the fan characteristic curves were drawn. Furthermore， the internal flow rules and stall behavior of axial-flow fan were analyzed. The results indicated that the fan characteristic curves show an unstable operation region， in which the inflection point exists. Compared with the working condition， the minimum value of static pressure in the impeller area is higher， and the static pressure gradient of the blades significantly drops under the stall condition. When the stall occurs， the curvature of streamline tends to be severe， and the whirlpool zone extends at the tail.Based on the results， the stall point is predicted when the flow coefficient value is 0.201.

Key words: axial-flow fan, flow field, stall point, stall behavior, numerical simulation