固壁与固壁相交所成二面角对附近区域内附面层发展具有重要影响,尤其在风扇/压气机中,控制叶表与端壁相交二面角及其流向变化是调控角区分离的重要方向.本文以具有不同二面角的四种典型扩张管道(扩张角3°)为模型案例,采用数值方法研究了不同二面角角下扩张管道内附面层发展规律,印证了二面角原理,并由数值计算结果拟合得到了分离位置经验公式.“,”The dihedral angle between two intersected solid wall have great influence on the development of the boundary layers at the corner,especially on the fan or compressor.The controlling of the dihedral angle and it's development along the streamwise is an important method to limiting the corner separation.This paper make an numerical investigation on four kinds of diffusion pipes with different dihedral angles.Through the numerical method,the law of the boundary layer development at different dihedral angle was investigated,which confirmed the dihedral principle,and the dihedral principle is quantified through the investigation on diffusion pipes.