Numerical Study of the Air Bleeding Caused Non-Uniformity in Axial Compressor

Bleeding in the compressor is getting more and more attractive because the increasing demand of bleeding rate as the temperature of the first stage of turbine gets higher and needs more cooling air. Though plenty of work has been done about bleeding, however, most of the work is studied with a single passage or ignoring the real structure of the bleeding system. In the present study, multi-passage calculation was used through ANSYS CFX to consider the finite duct holes in the whole blade row, and the effect of the axial location of bleeding slot on the non-uniformity of the blade passage was investigated, and the non-uniform could maintain a low level when bleeding at the front part of the blade passage and the non-uniformity would become large when moving the bleeding slot much further downstream. Afterward, the air bleeding mass flow rate was studied. It's found that the non-uniformity of air bleeding mass flow is small when bleeding at a low mass flow rate in each passage and results in relatively uniform flow field in the passage. However, the non-uniformity increases significantly as the bleeding mass flow rate increases. Some flow field details were also given to study how the flow field changes when bleeding non-uniformly.