Abstract: A theoretical model that shows the correlation of geometry parameters of cooling fans， rotation speed and volume flow rate was established by using the classic blade element-momentum theory of wind turbines for the axial cooling fan of vehicles. This model revised the load direction on the blade element of blade element-momentum and the inlet and outlet boundary conditions and so on， based on the difference of energy transfer between cooling fans and wind turbines. Then， the experiment and simulation based on computational fluid mechanics were carried to test the precision of the theoretical model for the volume flow rate of cooling fans. The results showed that the theoretical computational method for volume flow rate of cooling fans not only reflects the change of volume flow rate with the rotation speed of fans， but also has high calculation precision. In the researched model， the average relative error between the theoretical calculation method and experiment is 3.57%， and the one between the theoretical calculation method and CFD is 5.03%.

Key words: cooling fan, volume flow rate, blade element-momentum theory, theoretical calculation method and validation