Efficiency Improvements for eVTOL Based on Vented Duct Geometry

In reality, eVTOL aircraft have substantial promise in revolutionizing transportation within cities and other short distances due to their ability to take off in confined spaces and the low emissions and noise generated with eVTOL aircraft. However, eVTOL aircraft are still limited by battery technology. Current battery systems draw inspiration from the automotive sector and are capable of ranges of up to 150 miles. Continuing to increase efficiency will be beneficial to allow eVTOL aircraft to be used in applications where greater range is needed, e.g., search and rescue and in the general UAM application to further shorten downtime experienced for charging. In this study, a novel vented duct geometry utilizing entrainment is investigated and found to have doubled thrust generated. The test and reference duct were constructed utilizing a modified NACA airfoil and tested with Simscale CFD software. The vented duct geometry was found to produce a significant thrust increase over a reference duct. Nevertheless, the need was found for optimizing the vent geometry as eddy currents were observed to appear and thus limit the amount of air entrained. Other analysis methods including PIV were suggested to optimize the geometry to prevent eddy currents. Adopting the geometry would allow for increases in range without the need for complex additional energy stores (e.g., hydrogen), decreasing cost and complexity needed to optimize efficiency of eVTOL aircraft. Successfully implementing this propulsor geometry would unlock applications like regional routes and longer endurance/range operations.