Characterization of the low-noise drone propeller with serrated Gurney flap

Abstract

Drones, which have become increasingly popular in recent years, produce a lot of noise due to the movement of their propellers. When flying near humans, especially as in urban situations, noise suppression is critical. It has been demonstrated that noise can be minimized by increasing propeller lift per unit rotation speed and decreasing propeller rotation speed by expanding propeller area or designing the airfoil shape. This study developed a new structure, serrated Gurney flap, by merging the Gurney flap, which is the trailing-edge structure of an airfoil, and the serration, which is the low-noise structure found in an owl feather, and studied its performance through experiments and numerical simulations. The results indicated that the structure can boost the propeller’s lift coefficient while reducing the vortex separation induced by the Gurney flap and suppress propeller noise by slowing the propeller. Further modification of its structure may result in improved efficiency as well as decreased noise level.

Proposal of Practical Sound Source Localization Method Using Histogram and Frequency Information of Spatial Spectrum for Drone Audition

“…The second is the development of SSL methods. To suppress the decline of localization performance due to the ego-noise of drones, low-noise propellers have been developed [13][14][15]. The third is the development of high-performance SSL methods.…”

Near- and Far-Field Acoustic Characteristics and Sound Source Localization Performance of Low-Noise Propellers with Gapped Gurney Flap

“…In our previous study, we conducted research to apply Gurney flaps to drone propellers with the aim of achieving broadband noise reduction by reducing rotational speeds, tone noise reduction by reducing wing tip speeds [27,28], and high-frequency band noise reduction by interfering with vortices shed from the trailing edge. As a result, we developed a low-noise propeller inspired by Gurney flaps for drone applications [29]. One objective of this study is to comprehensively evaluate the effect of the developed low-noise propellers on noise characteristics.…”

Microfiber coating for propeller noise reduction

“…Passive means, such as the use of engineered surfaces, materials, or coatings, are particularly advantageous as they do not require an external power source or mechanical/electrical installation 7 . Serrated leading or trailing edges have been used for noise reduction [8][9][10][11][12] . Alternatively, a furry or a velvet-like surface can be applied to the propeller blade [13][14][15] .…”

“…Based on these findings, it is hypothesized that the microfiber-induced flow of these features can play a role in reducing propeller noise. Here, the sources of the propeller noise are schematically described in Figure 1 7,12,[21][22][23] . These are (A) the interaction of the turbulent boundary layer and the trailing edge known as the turbulent boundary layer trailing-edge noise (TBLTE), (B) vortex shedding associated with the laminar boundary layer known as the laminar boundary layer vortex-shedding noise (LBLVS), (C) the interaction of the propeller blade and the blade-tip vortex known as the blade vortex interaction noise (BVI), and (D) the interaction of the propeller blade and the turbulent wake formed by a preceding blade known as the blade wake interaction noise (BWI).…”