An Investigation of Post Stall Transients and Recoverability of Axial Compression Systems: Part II — Numerical Simulations

Using the method developed in part I, the calculations of limited parameters, recovery behaviors from stalled flow, and the effect of compression system parameters on the recoverability from rotating stall have been carried out in the present paper. It is shown that the response mode of unstability, rotating stall, classic surge or deep surge, depends not only on the parameter B, but also on the compressor axisymmetrical characteristics and the final throttle setting or the stalled equilibrium operating point, and the critical combination values of (B*H/W) or, which determines whether ultimate oscillation is deep surge, or classic surge (or rotating stall), are very similar for different compressor axisymmetrical characteristic. The calculations of transient recovery behaviors from stalled flow, surge or rotating stall, are carried out to present that the method can be used to investigate these problems, and then the effect of system parameters on the recoverability is investigated to show that the parametre B, the compressor length to radius ratio lc, and the compressor duct parameter in all have little effect on the recoverability at the compression system, but the reciprocal time-lag parameter of blade passage a and compressor axisymmetrical characteristic have strong effect on it. It has been found that decreasing the value of [H/W] can decrease the recovery hysteresis from rotating stall and improves the recoverability of the compressor. The results are consistent with experience.