球面端壁造型变几何涡轮流场和性能数值研究

摘要

To investigate efficiency characteris-tics and loss mechanism of Spherical end wall VGT(variable geometry turbine),a spherical end wall VGT reformed from a one stage high pres-sure turbine was numerical simulated in this study. Both the spherical end wall profiling and,espe-cially,the vane end leakage would lead to a de-crease of turbine efficiency.With vanes closing, guide vane wake loss and secondary flow loss in-creases,and causes a rapid decrease of turbine effi-ciency.With vane open at low pressure ratio,tur-bine efficiency would increase because of lower guide vane wake loss and secondary flow loss. Blades wake loss increases with vane open at high pressure ratio,which finally causes the decrease of turbine efficiency.%为了研究球面端壁变几何涡轮的效率特性及损失机理，对在一单级高压涡轮基础上改造而来的球面端壁变几何涡轮进行数值模拟。结果显示，对原始涡轮的球面端壁改造和导叶端区间隙的存在都会导致涡轮效率降低，且后者的影响更加显著。涡轮导叶关闭时，导叶尾迹损失和动叶二次流损失增强，造成涡轮效率急剧下降。导叶打开时，在低压比状态下导叶尾迹损失和动叶二次流损失被削弱，使涡轮效率得到提高；高压比状态下，动叶尾迹损失增大，导致涡轮效率降低。