低噪声无人机螺旋桨前缘锯齿设计与分析

DESIGN AND ANALYSIS OF SERRATED LEADING EDGE OF LOW NOISE UAV PROPELLERS

胡海涛

11849153

硕士

力学

刘宇

2020-05-28

2020-06-08

哈尔滨工业大学

深圳

多旋翼无人机目前在很多领域都运用广泛，如测绘、航拍、救援、快递服务等等。但是，无人机的气动噪声却是制约其民用的一个关键因素之一，因此降低无人机螺旋桨的噪声非常有意义。受猫头鹰静音飞行和前缘锯齿在二维翼型研究的启发，这里将前缘锯齿应用于无人机螺旋桨。通过选择一系列参数，即不同高度和宽度的前缘延伸式锯齿螺旋桨，对前飞工况不同转速下的这些螺旋桨进行气动及噪声测试，探究锯齿参数对于螺旋桨前飞过程中的气动及噪声性能的影响，并寻找降噪规律以及最佳的锯齿参数设计。前缘锯齿结构减小了螺旋桨前飞过程中的推力，增大了扭矩和消耗功率，因而造成整体气动性能的降低，且螺旋桨的推力随锯齿高度的增大先增大后减小，随锯齿宽度增大而减小，扭矩和消耗功率则随锯齿高度增大不断增大，随锯齿宽度增大而减小。而针对相同高宽比的锯齿螺旋桨的分析，发现二者表现出相似的气动力学性能。在噪声性能方面，前缘锯齿结构显著降低了螺旋桨前飞过程的中高频宽频噪声，且中高频宽频降噪量对于锯齿宽度相对于高度更敏感，当锯齿宽度越小，宽频降噪量越大，而纯音噪声主要取决于不同锯齿螺旋桨的气动性能。此外，锯齿螺旋桨的频谱降噪量在达到最大值之前与降噪频率存在明显的线性对数规律。工业界判断锯齿设计是否有效的标准往往是当产生同等推力的情况下螺旋桨总噪声的大小，因此，前缘锯齿虽然降低了螺旋桨的气动性能，但却提升了其噪声性能，综合来看，产生同等推力的情况下，前缘锯齿实现了螺旋桨的降噪，且高度最大的锯齿螺旋桨降噪量最大，7200 rpm转速下降噪量达到将近3 dB。具有相同高宽比的锯齿螺旋桨的气动-噪声综合性能也相似，因此，高宽比可能是决定螺旋桨气动-噪声性能的更关键因素，后面可以对其进行参数化研究。

Multi-copters are currently widely applied in many applications, such as mapping, aerial photography, rescue operations, logistics and so on. However, the aerodynamic noise of UAV is one of the key factors restricting its civil application, so reducing the noise of propellers can help UAV manufacturers design more competitive products. Inspired by the silent flight of the owls and the research of the serrated leading edge in the two-dimensional airfoils, the serrations were applied on the propeller of a commercial quadcopter. By choosing different parameters of serrations, i.e. the height and wavelength, the aerodynamic and noise tests of these propellers at different rotational speeds were conducted. The parameter is chosen in such a way so as to explore the aerodynamic and aeroacoustic performance of isolated multi-copter propellers at the forward flight condition, and to search the law of sound pressure lever reduction (∆SPL) and the best designed propeller of the serration parameters. The serrations reduce the thrust during the forward flight of the propeller, and increase the torque and power consumption, thereby reduce the overall aerodynamic performance. The thrust of the propeller increases and then decreases while increasing the height of the serration. However, the thrust decreases monotonically while increasing the wavelength. The torque and power consumption increase while increasing height of the serration, and decrease while increasing the wavelength. The analysis of data from the serrated propellers with the same aspect ratio shows that the two propellers are similar in aerodynamic performance. In terms of aeroacoustic performance, the leading edge serrations significantly reduce the mid and high frequency broadband noise during the forward flight, and the mid and high frequency broadband noise reduction is more sensitive to the wavelength than the height. The smaller the wavelength of serration is, the larger the broadband noise reduction will be. The tonal noise mainly depends on the aerodynamic performance of different serrated propellers. In addition, the sound pressure level reduction of the serrated propeller has a significant linear logarithmic law with the frequency before reaching the maximum. From the application perspective of UAV and propeller manufacturers, the noise emission is compared when the two propellers generate the same thrust. Therefore, although the leading edge serrations reduce the aerodynamic performance of the propeller, they improve propeller’s acoustic performance. When generating equal thrust, the leading edge serrations reduce the noise emission, and the propeller with the highest serrations has the largest noise reduction. The aerodynamic-aeroacoustic performance of serrated propellers with the same aspect ratio is also similar. Therefore, the aspect ratio may be a more critical factor determining the aerodynamic-aeroacoustic performance of the propeller, which is recommended for future study.

无人机螺旋桨 前缘锯齿 气动性能 噪声性能

UAV propeller serrated leading edge aerodynamic performance aeroacoustic performance

中文

联合培养

南方科技大学

胡海涛. 低噪声无人机螺旋桨前缘锯齿设计与分析[D]. 深圳. 哈尔滨工业大学,2020.