Engineers have figured out how to design an electric aircraft propeller that is both quiet and efficient. article about it published in aviation.
In the last decade, many airplanes with electric motors have been created. They emit no harmful emissions and contain no jet or piston engine noise. However, it is not possible to completely silence the air currents around the wings. The more blades on the propeller, the less noise there is, but at the same time efficiency drops, which reduces the aircraft’s range.
Scientists at Chalmers University of Technology were able to isolate and study the noise produced at the tips, or “tip vortices,” of propeller blades. This is the least understood source of propeller noise. By isolating this noise, the researchers were able to understand its role relative to other noise sources. As a result, the scientists were able to achieve a better compromise between efficiency and noise by adjusting a number of propeller parameters, such as angle of attack, blade bearing chord length and number of blades.
“Modern propellers typically have two to four blades, but we have found that using six blades designed using our optimization scheme you can design a relatively efficient and quiet propeller. The resulting propeller is 5-8 with a thrust reduction of only 3.5% compared to three-bladed propellers. decibels provides a noise reduction,” the authors explain.
The authors hope that their technology will make it possible to create an electric aircraft suitable for regular flights over residential areas.