Subjected to an oscillating flow rate, a compressor may feed additional (excitational) energy into the attached piping system. The relation between this additional energy input and the instantaneous behavior of a centrifugal compressor stage is dealt in a first part. Modeling the stage behavior by taking into account either inertia of the enclosed fluid mass or a first-order transient element or transient stall in any component leads to a different energy input. The energy input at a flow rate oscillation of given frequency and amplitude was calculated as a function of the slope of the characteristic and the reduced frequency applying a previously published model to describe the instantaneous behavior of the stage. In this model transient stall in the diffuser is taken into account. At reduced frequencies above unity the energy input of the diffuser was reduced by a considerable amount due to the specified instantaneous behavior of the diffuser. This indicates a potential to reduce the additional energy input of the diffuser either by increasing the time constant of the stall process or by increasing the mild surge frequency. For the investigated diffuser size the required reduced frequencies imply mild surge frequencies in a range being too high for industrial application (>200 Hz). Still, this method turned out to give useful insight into the link between the instantaneous behavior of the compressor and its energy input. In a second part for the same centrifugal compressor the energy contribution of several stage segments during mild surge oscillations was determined from detailed instantaneous measurements. As a result, the contribution of each stage segment to the conservation of the mild surge pulsation emerges. Although at the investigated mild surge frequencies the stage segments no longer behave strictly quasi-steadily, their contribution to the additional energy input is found to be mainly determined by the slope of their quasi-steady characteristic.

Abdel-Hamid, A. N., 1985, “Dynamic Response of a Centrifugal Blower to Periodic Flow Fluctuations,” ASME Paper No. 85-GT-195.
Bons, J. P., 1994, “Dynamic Surge Behavior of a Centrifugal Pumping System,” ASME Paper No. 94-GT-150.
Clements, W. W. and Artt, D. W., 1987, “The Influence of Diffuser Channel Geometry on the Flow Range and Efficiency of a Centrifugal Compressor,” Proceedings, Inst. IMachE, Vol. 201 No. A2 (C41/8).
Bloch, G. S. and O’Brien, W. F., 1992, “A Wide-Range Axial-Flow Compressor Stage Performance Model,” ASME Paper No. 92-GT-58.
Davies, M. W. Jr., Owen, A. K., O’Brien, W. F., and Cousins, W. T., 1995, “Joint Dynamic Airbreathing Propulsion Simulations Partnerships (JDAPS),” ASME Paper No. 95-GT-279.
Fink, D. A., Cumpsty, N. A., and Greitzer, E. M., 1991, “Surge Dynamics in a Free-Spool Centrifugal Compressor System,” ASME Paper No. 91-GT-31.
Greitzer, E. M., 1975, “Surge and Rotating Stall in Axial Flow Compressors: Part 1—Theoretical Compression System Model,” ASME Paper No. 75-GT-9.
E. M.
, “
The Stability of Pumping Systems—The Freeman Scholar Lecture
ASME Journal of Fluids Engineering
, Vol.
, pp.
K. E.
, and
P. S.
, “
Experimental and Theoretical Study of Surge in a Small Centrifugal Compressor
ASME Journal of Fluids Engineering
, Vol.
, pp.
Hunziker, R., and Gyarmathy, G., 1993, “The Operational Stability of a Centrifugal Compressor and its Dependence on the Characteristics of the Subcomponents,” ASME Paper No. 93-GT-284.
Hunziker, R., 1993, “Einfluss der Diffusorgeometrie auf die Instabilitia¨tsgrenze des Radialverdichters,” Thesis, ETH Nr. 10252, ETH Zurich.
Japikse, D., 1987, “The Technology of Centrifugal Compressors: A Design Approach and New Goals for Research,” lecture notes on the flow in centrifugal compressors, Von Karman Institute, Brussels.
Kenny, D. P., 1972, “Lectures on the radial compressor,” Von Karman Institute, Brussels.
Lo¨hle, M., 1986, “Experimentelle und theoretische Untersuchung des dynamischen Betriebsverhaltens eines dreistufigen Radialverdichters,” Thesis, Universita¨t Stuttgart, Germany.
Ribi, B., and Gyarmathy, G., 1993, “Impeller Rotating Stall as a Trigger for the Transition from Mild to Deep Surge in a Subsonic Centrifugal Compressor,” ASME Paper No. 93-GT-234.
Ribi, B., and Gyarmathy, G., 1995, “The Behavior of a Centrifugal Compressor Stage during Mild Surge,” paper presented at the 1rst European Conf. Turbomachinery—Fluid Dynamic and Thermodynamic Aspects, VDI Berichte Nr. 1186.
Simon, J. S., Valavani, L., Epstein, A. H., and Greitzer, E. M., 1992, “Evaluation of Approaches to Active Compressor Surge Stabilization,” ASME Paper No. 92-GT-182.
Stein, W., 1986, “Beitrag zur Analyze der gegenseitigen Beeinflussung von Laufrad und Diffusorbeschaufelung in Radialverdichtern,” Thesis, Hannover.
Verdonk, G., 1978, “Theoretical and Experimental Investigation of the Flow at the Inlet of the Vaned Diffuser for a High Pressure Ratio Centrifugal Compressor,” Technical Note 125, Von Karman Institute, Brussels.
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