Turbocharger turbines in internal combustion engines operate under highly pulsating flow conditions. The pulsating inflow has a complicated interaction with the turbine flow field and generates strong unsteadiness across the turbine stage, which produces oscillatory behavior and renders turbine performance distinct from that under steady conditions. However, the unsteady effect of the pulse flow is not considered when matching turbocharger turbines to engines due to the lack of effective simulation tools and unsteadiness criterion.
In this paper, a one-dimensional (1D) unsteady turbine model is proposed which could consider the volute curvature and preserve circumferential non-uniformity at rotor inlet. A parametric investigation of the response of a turbocharger turbine to inlet pulses is conducted based on the 1D model. The effects of various pulse parameters such as the amplitude, load, and frequency on the unsteady performance loops are studied. The influence of turbine operating conditions as the average inlet temperature and rotating speed on turbine unsteady performance is assessed. A dimensionless unsteadiness criterion Λ is used to correlate the relative importance of turbine unsteadiness. Results show that Λ is an effective criterion to judge the relative importance of unsteadiness. The investigation demonstrates turbine behaviors under different pulsating flow conditions, and strengthens the understanding of pulsating flow effect on turbine unsteady performance.