Detecting Rotating Stall Precursors in Axial Compressors via Perturbations Part 1: Theory

You are here: Homepage > Search

Detecting Rotating Stall Precursors in Axial Compressors via Perturbations Part 1: Theory

Dong, Wanjing / Wang, Yong

The nonlinear dynamics of fluid instabilities such as rotating stall and surge in axial compressors are typically modeled as subcritical Hopf bifurcations with hysteresis. In this paper, nonlinear dynamical systems with subcritical Hopf bifurcations under periodic forcing are analyzed, and the theoretic results are applied to prediction of rotating stall precursors. Depending on the forcing amplitude and frequency, there are possibly two types of features for the periodic solutions as the bifurcation parameter approaches the critical values. For the first type, the sensitivity of the amplitude of the periodic orbits to the bifurcation parameter becomes infinitely large while the amplitude itself remains finite, which corresponds to the double-cycle bifurcation of the periodic orbits, whereas, in the second case, though the sensitivity is not as steep, there are secondary resonant peaks in the power spectrum in addition to those of the multiples of periodic orbits. These secondary resonant spikes correspond to the Neimark–Sacker bifurcation of periodic orbits, which typically leads to quasi-periodic orbits. These two types of prominent features can serve as precursors to subcritical Hopf bifurcations. The theoretic results are applied to the Moore–Greizter model for rotating stall in axial compressors. In the second part of the paper, experiments are carried out on a single-stage low-pressure axial compressor with inlet circumferential distortions, and it is demonstrated that the theory can yield identification of rotating stall precursors much earlier than the case without distortions.