Analysis and characterization of a marine turbocharger’s unstable performance

Abstract

In this article, the results of an extended set of experiments on a turbocharged four-stroke marine diesel engine are presented. By modifying the engine’s intake manifold and injecting compressed air into it, it was possible to raise the pressure downstream of the turbocharger’s compressor and force it into unstable operation. Tests were performed through the entire operating envelope of the engine. Depending on the operating mode of the engine (steady state, transient) and the operating load, it was possible to identify different forms of compressor instability. The equipment used enabled the creation of detailed profiles of engine and turbocharger performance. By applying time- and frequency-domain analysis tools, the measurements were utilized to characterize the extent and form of instability taking place at each operating point of the engine. The results and correlations made along with remarks on the instrumentation used during the experiments can be used to provide quantitative input for surge control–oriented models and the development of control systems for surge avoidance and mitigation. Moreover, they will be used as experimental reference for the validation of a surge model-engine simulation code combination.