动叶可调轴流风机前后级叶轮单叶片非同步调整时的内流特征

Internal Dynamics of a Variable-pitch Axial Flow Fan During Non-synchronous Adjustment of Single Blade on the First-or Second-stage Impeller

对某两级动叶可调轴流风机进行了整机三维定常数值模拟,研究了不同工况下第一、第二级叶轮单叶片安装角发生非同步调整对风机整机、单级叶轮以及异常叶片周围流场的影响.结果表明:叶片安装角发生小角度偏离时,风机的全压和效率均变化不大,随着偏离度Δβy的增大,风机性能显著恶化;第一级叶轮异常时风机的整体性能、单级叶轮的总压升能力和异常叶片自身的做功性能以及前后级导叶效率均劣于第二级叶轮异常时,尤其是负向偏离时表现更显著,仅Δβy=12°时优于第二级叶轮异常时;正向偏离时,第一、第二级叶轮的熵产率和流线分布呈相似规律,均在异常叶片吸力面侧尾缘形成高熵产率区和分离涡,其大小随Δβy增大而增大;负向偏离时,第一级叶轮异常时在异常叶片的压力面侧为高损失区,而第二级叶轮异常时则对相邻叶片的吸力面产生影响,并在其尾部形成分离涡.

Three-dimensional steady numerical simulation was carried out to a two-stage variable-pitch axial flow fan,so as to study the effects of non-synchronous adjustment of single blade fixed on the first-or second-stage impeller on the flow field around the fan,single impeller and the abnormal blade.Results show that the full pressure and efficiency of fan show little change when the blade installation angle deviates slightly;the fan performance deteriorates obviously with the increase of deviation degreeΔβy;in the case the abnormal blade is on the first-stage impeller,the overall fan performance,the total pressure rise capability of single-stage impeller,the work capability of abnormal blade itself,and the guide blade efficiency will all be inferior to those in the case the abnormal blade is on the second-stage impeller,especially with negative deviation of installation angles,exceptΔβy=12°;for positive deviations of abnormal blade,the entropy generation rate and streamlines of both the first-and second-stage impeller present similar distri-butions,with high entropy generation region and detached eddy forming in the trailing edge on suction side of abnormal blade,which expand with growingΔβy;in the case of negative deviation,when the abnormal blade is on the first-stage impeller,high loss region will occur on the pressure side of abnormal blade,whereas when the abnormal blade is on the second-stage impeller,detached eddy will generate in the trailing edge on suction side of adjacent blades.