波浪形前缘叶片对动车组牵引变压器冷却风机气动性能及噪声特性的影响

Effects of wavy blade leading edges on aerodynamic and aeroacoustic performances of fans used for cooling EMU traction transformers

对现有冷却风机噪声进行测试,并利用LES方法和FW-H方程,建立冷却风机的流场和气动噪声预测模型。利用验证后预测模型,参考驼背鲸鳍肢前缘凸起的波浪形结构,设计3款具有正弦曲线波浪形前缘结构的叶片并应用于出风口叶轮。对比分析装配原型叶片的风机模型和装配波浪形前缘结构叶片的风机模型间流场和远场气动噪声的差异。研究结果表明:现场测试与预测模型的一致性较好;与原型叶片相比,设计的3种叶片可使距出风口1 m处的噪声测点的A计权总声压级降低量达4.5 dB;使用具有波浪形前缘结构的叶片可以提高冷却风机的流量和效率;波浪形前缘结构通过改变叶片前缘的压力梯度分布、破坏前缘处的涡结构及降低叶顶泄漏流的强度可有效降低冷却风机的气动噪声,其中宽频噪声降噪显著,且波浪形前缘结构的波长越短,降噪性能越好。

The noise of cooling fan was tested,and the flow field and aerodynamic noise prediction model of cooling fan was established by using LES method and FW-H equation.Using the model which was verified,referring to the wavy structure of the fin front edge of humpback whales,three blades with wavy leading edge were designed and applied to the outlet blades.Differences in flow field and far-field aerodynamic noise were analyzed between the original design and the new design.The results show that the field test is in agreement with the prediction model.The new design can reduce the A-weighted noise level measured 1 m away from the air outlet by up to 4.5 dB.The flow rate and efficiency of the cooling fan can be improved by using blades with a wavy leadingedge structure.The wavy leading-edge structure can effectively reduce the aerodynamic noise of the cooling fan by changing the pressure gradient distribution at leading blade edges,destroying the vortex structure there,and reducing the intensity of the tip leakage flow,and the reduction of broadband noise is remarkable.The shorter the wavelength of the wavy leading-edgestructure is,the better noise reduction performance is.