双螺旋浆干涉降噪试验研究

目的研究在机体两侧螺旋桨声波干涉状态下,机体假件表面的降噪效果。方法通过模拟双螺旋浆在机体两侧的分布结构,以壳体结构模拟机身壁板,两侧对称布置电机驱动的螺旋桨旋转台,搭建双桨干涉试验平台,控制螺旋桨运行状态,测量机身表面声压级分布,得到螺旋桨旋转平面内机身外表面的声压级分布规律。通过对比单桨运行状态与双桨干涉状态测点的声压级,验证双桨干涉对机体的降噪效果。结果双桨干涉具有明显的降噪效果,尤其是机体45°方向测点降噪效果最明显。与单桨运行状态相比,双桨对消状态下,最大降噪量为1.84 dB,靠近螺旋桨旋转中心测点(0°测点)声压级降低1.58 dB,机体最上方测点(90°)噪声略有上升,声压级增加0.29dB。结论双桨同时运行状态下,降低了机体表面一定区域的声压级,且对其余区域声压级增加较小,通过控制双桨运行状态能达到降噪的目的。

Experimental Investigation on Noise Reduction of Double Rotating Propellers

Objective To investigate the noise reduction of acoustic wave interference produced by double rotating propellers (AWIDRP) on airframe surface. Methods In this paper, an experimental platform was designed and build by simulating the symmetrically arrangement of two propellers on both sides of airframe. The airframe was approximated by a cylindrical shell and the propellers were driven by servo motors. When the propellers were rotating, sound pressure levels (SPL) on the airframe surface were measured. According to the measuring data, the SPL distribution law of airframe was obtained. By comparing the SPL of each measuring point under the condition of single-propeller rotation and double-propeller rotation, the noise reduction of AWIDRP on airframe surface was verified. Results The double-propeller rotation has apparent noise reduction effect, especially at the 45° measuring point of the airframe. Compare with single-propeller rotation, the SPL of the most areas on airframe surface was decreased in AWIDRP state. The max noise reduction was 1.84 dB at 45°measuring point. The SPL at 0° measuring point was re-duced by 1.58dB. The SPL at 90° measuring point on the airframe was increased by 0.29 dB. Conclusion In state of AWIDRP, the SPL in the main area on airframe surface is decreased, only increased in a few areas. The AWIDRP was effective in noise reduction on airframe.