不同攻角下压气机叶栅涡流噪声辐射特性的研究

Research on Vortex Noise Radiation of Compressor Cascade Under Different Attack Angle

采用大涡模拟模型和边界元方法对压气机叶栅的非定常流场与声场进行了分析,研究了来流攻角对叶栅尾缘非定常涡脱落及其噪声辐射特性的影响.结果表明:压气机叶栅流场中存在着尾缘涡脱落现象,尾缘涡脱落的强度随着攻角的变化而变化.在较大的正攻角下,吸力面存在的分离涡与下游的尾涡相互影响,引起较大的升力脉动,使得噪声辐射增强;而在较大负攻角下,压力面的分离涡同样影响尾缘涡的脱落,噪声辐射水平也有增强趋势.来流攻角对噪声辐射的指向性影响不大.声压级的最小值出现在阻力系数最小的攻角下.

In order to investigate the influence of attack angle of compressor cascades on unsteady vortex shedding at trailing edge and the noise radiation,large eddy simulation model and boundary element method were used to analyze the unsteady flow and acoustic field.Results show that unsteady vortex shedding exists at the trailing edge of compressor cascade,and the shedding strength varies with attack angles.The vortex separation on suction side with large positive attack angle affects the downstream trailing vortex,which causes large lift fluctuation and strengthens the noise radiation;whereas the separation on pressure side with large negative attack angle also influences the trailing-edge vortex shedding and strengthens the noise radiation.However,the attack angle of coming flow has little impact on directivity of noise radiation.The minimum value of sound level appears at an attack angle of least drag.