The best efficiency point of an axial fan at low-pressure conditions

Abstract

In the current work, the objective is to determine the best efficiency point (BEP) of an axial fan using CFD. Analyzing the performance of the fan based upon the parameters chosen can lead to the optimal design of an axial flow fan for aerospace applications where the ambient pressure varies rapidly. The 2-bladed fan chosen for the study is the Propimax 2L which is considered the base fan used for comparison of all the results of the work. The set of parameters tested were fan rotational speed, ambient pressure conditions, blade count, and the airfoil design. All the performance measures were based on overall fan efficiency. The results yield the following: an increased rotational speed led to higher efficiencies, the most efficient ambient pressure of which the fan can perform is 0.7 atm, a 5-bladed fan configuration produced the highest efficiency, and airfoil selection is critical for fan efficiency enhancements. The results demonstrated that at 0.7 atm the fan efficiency is the highest due to the changes in power consumption to the density effect. A key finding in the work is that higher blade counts do not necessarily lead to higher performing axial fans. A high cambered airfoil provided a higher flow rate at free delivery than that of the Propimax 2L design, but the rotorcraft airfoil did not yield favorable results. The analysis is focused on the fan design of cooling of the electromechanical actuators (EMAs).