Experimental Analysis for Performance Evaluation and Unsteadiness Quantification for One Turbocharger Vane-Less Radial Turbine Operating on a Gasoline Engine

Abstract

Most of the available test rigs of turbochargers use a specified device to reproduce the waveform of the engine exhaust gas which is not physically pertinent regarding that several parameters can influence the pulse form of the flow at the engine exhaust manifold. In order to overcome this drawback, a new test rig of one turbocharger vane-less radial turbine operating on a four-stroke engine to characterize this turbomachine under its real flow conditions was built. Based on test data collected from the test rig, developed at the National School of Engineers of Sfax, a characterization of the turbine performance under different operating conditions has been carried out. To validate the experimental methodology, an uncertainty analysis has been performed. The results prove that the performance and flow characteristics of the studied turbine present a high sensitivity to the gas waveform and the pulse frequency of the flow coming from the engine exhaust manifold. Besides, a Strouhal number analysis using a fast Fourier series transform has been made to characterize the unsteadiness level of the flow within the present turbine. The results show an important impact of the pulse frequency on the turbine unsteady characteristics.