Multistage Centrifugal Compressor Surge Analysis: Part II—Numerical Simulation and Dynamic Control Parameters Evaluation

Abstract

This paper describes, from a theoretical point of view, the behavior of compression systems during surge and the effect of passive and active control devices on the instability limit of the system. A lumped parameter model is used to simulate the compression system described in Part I of this work (Arnulfi et al., 1999), based on an industrial multistage centrifugal compressor. A comparison with experimental results shows that the model is accurate enough to describe quantitatively all the features of the phenomenon. A movable wall control system is studied in order to suppress surge in the compressor. Passive and active control schemes are analyzed; they both address directly the dynamic behavior of the compression system to displace the surge line to lower flow rates. The influence of system, geometry and compressor speed is investigated: the optimum values of the control parameters and the corresponding increase in the extent of the stable operating range are presented in the paper.

Multistage Centrifugal Compressor Surge Analysis: Part I — Experimental Investigation

“…Surge oscillations are observed when VAR 5 26°/., but at VAR values of 26% and 24% the phenomenon is not periodic, any reverse flow is absent and the instability oscillations of the now velocities are very small when compared with the flow rate and pressure ones. As it is demonstrated in Part II (Arnulfi at al., 1998), such conditions correspond to virtually stable operating points, the equilibrium steady-state flow coefficients being slightly greater than the stall limit value. However, a small perturbation is sufficient to cause a pronounced, but temporary, system instability.…”

“…Detailed measurements in surge instability conditions were performed on a low-pressure compression system. The analysis of the flow rate and pressure measurements in the plant and of the flow velocities signals in the diffusers of the multistage centrifugal compressor allowed the unsteady system behaviour to be fully operating range of the compressor through suppression of surge (Arnulfi et al, 1998).…”

“…1). Different configurations of this multi-stage compressor were investigated in previous works, by performing flow velocity measurements both in steady conditions (Arnulfi et al, 1995) and during rotating stall (Arnulfi et al, 1996).…”

“…This compressor offers the possibility of varying its configuration, so allowing the influence of the geometry on surge features to be investigated. Detailed measurements of pressure, flow rate and instantaneous velocities in the compressor diffusers have been performed in order to understand the instability behaviour in more details and to collect experimental data to be used for validating the theoretical model of the compression system described in the part II of the present work (Arnulfi et al 1998).…”

Stability Improvement of High-Pressure-Ratio Turbocharger Centrifugal Compressor by Asymmetrical Flow Control—Part II: Nonaxisymmetrical Self-Recirculation Casing Treatment

“…A lot of research has been done to improve the flow range of high-pressure-ratio centrifugal compressors [7][8][9][10]. Generally there are two types of stability enhancement.…”