An Actuator-Disk Model Augmentation for Low-Pressure Axial Fan Simulation

Actuator-disk rotor models are important simulation tools for cost-effective industrial axial fan system analysis. Actuator-disk fan model performance, however, is constrained by the conventional use of two-dimensional airfoil coefficient input data, which limits the accuracy of the models to a narrow operating range free from significant radial blade flow. Radial blade flow is characteristic of off-design fan operation, which is often unavoidable within typical industrial fan system environments, so the enhancement of actuator-disk model performance for these conditions is desired. This paper accordingly presents a new means of robustly determining actuator-disk model coefficient inputs that are suitable for a wide range of fan operating conditions. The proposed augmented actuator-disk method (AADM) capitalizes on new insights into the unique aerodynamic behavior of low-pressure axial fan rotors. The performance of the AADM is evaluated for two different industrial cooling fans and is shown to outperform existing actuator-disk coefficient formulations through computational fluid dynamics simulations. The AADM is shown to better predict key fan performance metrics, spanwise blade force distributions, and to produce flow fields that are more physically representative (an important feature for industrial heat exchanger studies where the AADM is anticipated to be commonly applied). The AADM has been developed to be easily adopted in generic industrial fan analyses and is expected to serve as a valuable springboard for future actuator-disk fan model developments.