齿形襟翼及跨度对风机气动性能影响的数值研究

Numerical Study on the Influence of Toothed Gurney Flap and Span on the Aerodynamic Performance of an Axial Fan

基于大涡模拟对采用不同跨度齿形襟翼(TGF)的动叶可调轴流风机进行了数值研究,探讨了襟翼及其跨度对风机性能、气动噪声和静压分布的影响,分析了噪声与涡结构分布的内在联系。结果表明:齿形襟翼可显著提高风机全压,且全压增幅与襟翼跨度成正比,襟翼跨度为0.9时的全压提高1 409 Pa;采用齿形襟翼后的风机降噪量随襟翼跨度的减小而增大,襟翼跨度为0.7时的降噪量达18.33 dB;齿形襟翼削弱了叶片尾迹强度,改善了叶根泡状涡尺寸,在襟翼顶部形成一较长管状涡,减弱了尾涡与叶顶泄漏流的相互作用;襟翼跨度越小,改善成效、降噪效果越显著;襟翼跨度为0.9时的齿形襟翼在改善全压、拓宽高效区和降噪等方面的综合性能最优,且在变安装角工况下可有效提升风机全压、改善大流量侧效率。

Based on large eddy simulation, a numerical study of a variable-pitch axial fan with different spans of toothed Gurney flap(TGF) was carried out. The effects of the TGF and span on fan performance, aerodynamic noise and static pressure distribution were explored, and the internal relationship between noise and vortex structure distribution was analyzed. Results show that the total pressure of the fan can be obviously increased with the TGF, its increase amplitude is proportional to the flap span, and the total pressure can achieve a rise of 1 409 Pa when the flap span is 0.9. The noise reduction of the fan with the TGF increases with the decrease of the flap span, when the latter is 0.7, the former reaches 18.33 dB. The TGF has a series of effects including weakening the wake strength of the blade, improving the root bubble vortex size, forming a longer tubular vortex at the top of the flap, and damping the interaction between the wake vortex and the tip leakage flow. The smaller the flap span, the more significant the effect of improvement and noise reduction. When the flap span is 0.9, the TGF has the best comprehensive performance in improving the total pressure, widening the high efficiency area and reducing noise, and it also has a notable improvement in the total pressure rise and the efficiency of large flow rate side under variable installation angles.