Steady state experimental characterization of a twin entry turbine under different admission conditions

The increasingly restrictive limits on exhaust emissions of automotive internal combustion en-gines imposed in recent years are pushing OEMs to seek new solutions to improve powertrain efficiency. Despite the increase in electric and hybrid powertrains, turbocharging technique is still one of the most adopted solution in automotive internal combustion engines to achieve good ef-ficiency with high specific power levels. Nowadays turbocharged downsized engines are the most common solution to lower CO2 emissions. Pulse turbocharging is the most common boosting layout in automotive applications as the best response in terms of time-to-boost and exhaust energy extraction. In high fractionated engine with four or more cylinders twin entry turbine can be adopted to maximize pulse turbocharging benefits and avoid interaction in the discharge phase of the cylinders. The disadvantages of the twin entry turbine are mainly due to the complexity of the exhaust piping line and the high amount of information required to build a rigorous and re-liable matching model. This paper presents a detailed experimental characterization of a twin entry turbine with particular reference to the turbine efficiency and the swallowing capacity under different admission conditions. The steady flow experimental campaign was performed at the turbocharger test bench of the University of Genoa, in order to analyse the behaviour of the twin entry turbine in full, partial and unbalanced admission. These conditions are those in which the turbine must work instantaneously during its normal operation in engine application. The results show a different swallowing capacity of each sector and the interactions between the two entries.