NUMERICAL-SIMULATION OF THE FLOW-FIELD NEAR AN AXIAL-FLOW FAN OPERATING UNDER DISTORTED INFLOW CONDITIONS

The results of numerical solutions of the Navier-Stokes equations, augmented by the k-epsilon model of turbulence, for an axial flow fan operating under distorted inflow conditions are presented. The fan is of the low solidity/low hub-to-tip ratio type: this type of fan has attained some importance with the advent of large directly air-cooled power stations in certain arid regions of the world. The numerical model is the SIMPLEN algorithm, which has been published by one of the authors previously. In the numerical predictions, blade element theory is used to model the thrust and torque exerted by the fan blades on the air. Experiments have shown that flow across the intake of a fan has a detrimental effect on its performance in that an increased amount of power is necessary to deliver the same flow rate as with no crossflow. The numerical results generally confirm the results of the experiment, although the increase in power is underestimated: an increase of only approximately half of the measured increase is predicted.