A direct comparison of unsteady influence of turbine with twin-entry and single-entry scroll on performance of internal combustion engine

Radial turbine with twin-entry scroll becomes prevailing recently due to its potential for energy recovery of internal combustion engine, especially at low speed condition. However, few quantitative comparisons of the impacts between this configuration and the conventional single-entry turbine have been performed on engine performance. This paper investigates unsteady influence of twin-entry and single-entry scroll on turbocharged engine performance via an in-house developed code ‘SPEED-Engine’ coupled with the geometry-based model of twin-entry turbine. Firstly, one-dimensional performance model of turbocharged diesel engine is established. Next, engine performance with two kinds of turbines is compared via the turbo-engine coupled model and confirms the 2.3% improvement of output power for the case with twin-entry. Further discussions manifest that swallowing capacity of twin-entry turbine varies with engine operational conditions, which has a similar function as a variable geometry turbine. The location of hysteresis loop is confirmed to be the reason for this phenomenon. Furthermore, a nominated throat area of twin-entry scroll is developed to compare the influence of twin-entry scroll on engine performance. Specifically, the nominated throat area is decreased by 28% at low engine speed. This investigation develops a convenient method to directly compare the effect of scroll configuration on engine performance. •1-D turbine model with twin-entry scroll coupled with engine model is established.•Engine power is improved at low speed due to pulse enhancement by twin-entry turbine.•Engine power is improved at high speed due to pulse separation by twin-entry turbine.•Twin-entry turbine works in similar behavior as variable geometry turbine does.•A nominated A/R is proposed to measure averaged twin-entry turbine performance.