离心压缩机级间加气的出口流场特性

Effect on the Next Stage Inlet Flow of the Complementary Gas Flow Between Centrifugal Compressor Stages

为了使离心压缩机中间某级加气后出口流场特性不影响其后所有级的运行及整机效率,以数值模拟的方式对离心压缩机的中间级加气结构内部三维流场进行了详细的研究.采用修改回流器叶型、增加叶片数目、增加叶片长度、修改叶片尾部型线为直线等方法消除了回流器叶片的分离与回流.同时,采用修改回流器子午流道型线及扭叶片代替直叶片的方法保证了出口流场的均匀性,使混合段出口气流角沿径向变化范围缩小了近20°.结果表明,依照上述方法对各部分加气结构进行合理设计及结构优化,得到了较为均匀的级间加气出口流场,可有效解决下一级进口流场畸变问题.该研究工作为设计高性能的中间级加气式离心压缩机提供了依据.

3-D internal flow of a centrifugal compressor with complementary gas added in space between stages was studied to improve the uniformity of the flow at the inlet of the next stage so that the performance of the stages thereafter and thus the efficiency of the whole unit were not affected adversely. Blade profiles, blade numbers, cord of the blade, and the straight line extension of the trailing edge were simulated numerically for the return channel blades in an attempt to avoid flow separation. The twist blades were designed and the meridian flow path was modified to reach a uniform flow field at the end of the mixing of the complementary gas with the main flow. The variation of the flow angles at the inlet of the next stage was reduced by nearly 20 degrees. Numerical results indicate that the final structure design can effectively solve the problem of the next stage inlet distortion.