基于CFD的挖掘机冷却风扇及导风罩降噪研究

Noise reduction of excavator cooling fan and wind scooper based on CFD

针对某型挖掘机在工作过程中冷却风扇出口端噪声水平严重超标的问题,对风扇在旋转过程中的气动性能进行了研究。首先,建立了风扇与导风罩所形成的流体域有限元模型。基于CFD理论,运用Fluent软件对其流场进行了稳态数值模拟。分别探究了风扇与导风罩相关结构参数对其风量大小与噪声水平的影响。结合厂商提供的散热系统选型软件Optimiser,兼顾风量与噪声要求,得到了最适合该挖掘机的风扇及导风罩型号。优化结果表明,在提供相同风量的前提下,优化后的风扇噪声比原风扇的噪声降低了1.5 d B左右。随后,对该流体域进行了瞬态仿真,分析了风扇噪声的频率特性。仿真结果表明,风扇旋转噪声主要集中在低频段,为企业有针对性地对该频段噪声采取降噪措施提供了指导。

Aiming at the problem that the noise level on the outlet side of the cooling fan exceeded the national standard seriously during the working process of an excavator, researches on the aerodynamic performances of revolving fan were carried out. Firstly, the finite element model of the fluid domain which was formed by the fan and the wind scooper was established. Steady-state numerical simulations for the flow field were conducted by using Fluent based on CFD theory. The effects of relevant structural parameters of fan and wind scooper on their blo- wing rate and noise level were explored respectively. Taking account of both wind and noise requirements, the most suitable type of fan and wind scooper for the excavator were obtained by using Optimiser,a cooling system selection software provided by the manufacturer. The opti- mization results indicate that the noise of optimized fan reduced 1.5 dB compared to that of original one under the premise that it can provide the same wind as before. Then, transient simulations for the flow field were done to analyze the frequency performances of fan noise. The sim- ulation results indicate that the rotation fan noise concentrates mainly on low frequency stage which guided the company to take noise reduction measures for this frequency band noise specifically.