System influence on the surge behaviour of a centrifugal compressor

Abstract

Instabilities in turbomachinery operation may be originated by the intrinsic flow unsteadiness, sudden variations of operating conditions, and the interaction with the surrounding system. All impact both system stability and machine reliability.The current investigations focus on the system influence, experimental method, test rig layout, and instrumentation when handling with reverse and pulsating flow. The evaluation of the system influence on compressor behaviour during surge and the best testing approach to describe the unsteady area without introducing further instabilities are specifically addressed. The main investigations, through experimental analyses, include the effect of discharge volume, location of flow-meter in the test loop for a prompt detection of flow reversal, and thermal stresses leading to overheating. The results, presented in time and frequency domains, show the evolution of the most relevant parameters during the surge and reverse flow phenomena and play a key role for the simulation of more complex dynamic scenarios.