Transient Simulation of the Six-Inlet, Two-Stage Radial Turbine under Pulse-Flow Conditions

Dariusz Kozak,Paweł Mazuro

doi:10.3390/en14082043

Abstract

In recent years, the automotive sector has been focused on emission reductions using hybrid and electric vehicles. This was mainly caused by political trends promoting “green energy”. However, that does not mean that internal combustion engines (ICEs) should be forgotten. The ICE has still the potential of recovering energy from exhaust gases. One of the promising ways to recover energy is turbocharging. Over the years engine manufacturers have designed very efficient turbocharger systems which have greatly increased the overall engine efficiency. This led to pollutant emission reductions. This paper presents the results of the three-dimensional (3-D) numerical simulations of the two-stage, six-inlet turbocharging system under the influence of unsteady, pulsed-flow conditions. The calculations were carried out for three turbine speeds. The most interesting results of this study were the separation of exhaust gases coming from the six-exhaust pipes and the performance of both stages under pulse-flow conditions. The two-stage turbocharging system was compared against the single-stage turbocharging system and the results showed that the newly designed two-stage turbine system properly separated the exhaust gases of the adjacent exhaust pipes.

Highlights

The increasing trend of pollutant emissions reduction has forced engine manufacturers to focus their interest on hybrid and electric vehicles
That does not mean that internal combustion engines (ICEs) should be eliminated from commercial use
There are a lot of places in the ICE that can be improved to recover more energy from the exhaust gases

Summary

Introduction

The increasing trend of pollutant emissions reduction has forced engine manufacturers to focus their interest on hybrid and electric vehicles. The 1-D simulation of the engine performance, with the two-stage turbocharging system at different altitudes, showed a greater increase in the brake power and torque when compared to the singlestage turbocharger [10,11] Such simulations neglect the pressure losses inside ducts caused by the vortices, the 1-D calculations are in good agreement with the experimental data and require less computational time. The turbocompounding system is a type of multi-stage turbine system and one of the approaches to recover energy from exhaust gases In such a system, an auxiliary turbine is installed behind the turbocharger. A two-stage turbocharging system further increases the energy recovery of the exhaust gases Such systems are complex and require precise control over the position of the variable nozzle vanes.

Number of Elements

Outlet Boundary Conditions

Number of cores

Conditions at the outlet