Matching of Radial Inflow Turbines with Internal Combustion Engines Considering Pulsating Flows

Abstract

This paper investigates numerically the effects of pulsating exhaust gases on the operations of radial inflow turbines and their matching with internal combustion engines at full-load conditions. Both single- and twin-entry radial turbines are considered and the transient behaviors are analyzed by combining the CFD and analytical models. As results, the unsteady performances are shown to deviate noticeably from the steady state due to high levels of unsteadiness of the inlet conditions. A typical hysteresis-loop relating the effect of gas filling-emptying inside the volute is well depicted. Unsteady performance of the twin-entry radial turbine depicts that the of hysteresis-loop is wide due to large volute volume whereas the hysteresis-loop of single-entry turbine seems reducingas the amplitude of pressure pulse reduces. For the compressor side of the twin-entry radial turbine, and depending on the engine speed, the average values of unsteady performances exhibit deviations up to 9% in pressure ratio and 7.8% in airflow swallowing capacity, in contrast to the single-entry radial turbine these deviations are lesser about 4 and 4.9%, respectively. These differences could be related to the two sides of volute which are source of hysteresis and flow interaction.