Effects of the Inlet Boundary Layer Thickness on Rotating Stall in an Axial Compressor

Abstract

A three-dimensional numerical simulation was conducted to study an effect of the inlet boundary layer thickness on the rotating stall in an axial compressor. The inlet boundary layer thickness had significant effects on the hub-corner-separation in the junction of the hub and the suction surface. The hub-corner-separation grew significantly for the thick inlet boundary layer as the load was increased, while it was diminished to be indistinguishable from the rotor wake for the thin inlet boundary layer and a new corner-separation was originated near the casing. The difference in the internal flow at the near stall condition also had a large effect on characteristics of the rotating stall, especially the first asymmetric disturbance and the size of the stall cell. While a pre-stall disturbance arises firstly in the hub-corner-separation for the thick inlet boundary layer, an asymmetric disturbance was initially generated in the tip region because of the corner-separation for the thin inlet boundary layer. This disturbance was transferred to the tip leakage flow and grew to be an attached stall cell. When this attached stall cell reached a critical size, it moved along the blade row and became a short-length-scale rotating stall. The size of the stall cell for the thick inlet boundary layer was larger than that for the thin inlet boundary layer. The difference of the stall cell’s size affected the performance of the single rotor, causing large performance drop for the former case but a continuous performance change for the latter case.

Performance evaluation of a transonic axial compressor with circumferential casing grooves

“…Thus, this impact of flow instability on a whole system of gas turbine should be avoided. Many studies have been carried out to alleviate the stall and surge phenomena and to improve the operating stability of axial compressor through experiments and numerical analysis by many researchers together with the history of compressors [2][3][4][5].…”

Influence of the inlet boundary layer on non-axisymmetric endwall contouring effects in a linear compressor cascade

“…The loss characteristic and stall cell size were significantly influenced by the inlet boundary layer thickness according to Choi. 24,25 Wang 26 proposed that the thick inlet boundary layer reduced the working range and enhanced the secondary flow. As for the influence of the inlet boundary layer on CEW optimization, Li 27 found that there was a great difference in the optimal CEW geometry in cases with and without boundary layer skew.…”