Measurement of Instantaneous Fluid Dynamic Parameters in Automotive Turbocharging Circuit

In the paper the difficulties related to measurement of instantaneous fluid dynamic parameters in the turbocharging circuit of automotive engines under unsteady flow conditions are highlighted, referring to pressure, mass flow rate, temperature and turbocharger rotational speed. Frequency response of transducers, sensor position, measuring procedures and filtering techniques need to be taken into account to correctly describe the unsteady behaviour of tested component. The results of an experimental campaign developed on a small turbocharger for downsized gasoline engines are presented, focusing on the evaluation of the instantaneous parameters that allowed to estimate unsteady turbine performance. Measurements were performed by using a flexible test rig, operating at the University of Genoa, particularly suitable for investigations under unsteady flow operation.