Analysis on the Flow Stability of Streamlines in Axial-flow Compressors

In this paper, based on the general theory of the flow instability in turbomachinery, the streamline model is established. Using the proposed stability model and related calculation methods, the flow stability calculation of a typical axial-flow compressor is carried out. The calculation results show that the developed model can effectively capture the stability variation tendency of the streamlines at different spanwise locations and different operating conditions. On the theoretical calculation level, it reveals that the flow stability near the hub and shroud is worse than any other locations, especially the flow near the shroud, which determines the stability boundary of the system. In addition, according to the results of stability analysis and the observation of the velocity distribution at different spanwise locations and different operating conditions, the distribution of the flow velocity along the streamlines near the leading edge can be summarized into three forms: monotonous deceleration, acceleration first and then deceleration, and monotonous acceleration. From the stability point of view, the ideal velocity distribution is monotonous acceleration, followed by acceleration first and then deceleration, while the velocity distribution that ow begins to decelerate before arriving at the leading edge is detrimental to stability.