Performance Improvement of a Turbocharger Twin Scroll Type Turbine Stage   

The need for internal combustion engines with high efficiency and less CO2 exhaust rises as the government regulation over the environment tightened. One traditional solution to this problem is to implement a turbocharger, which compresses the inlet flow into the internal combustion engine by means of redundant energy from the engine exhaust gas. These turbo charged engines tend to have high fuel efficiency as well as low CO2 production rate while the size of the engine remains compact. Generally, the quasi-steady state assumption has been adopted for estimating the performance of turbine of the turbocharger. While this is reasonable approximation for single scroll turbocharger as long as the volute storage effect has been accounted. However, such may not be the case for twin-scroll turbocharger where the unsteadiness effect can become more prevailing.

An objective here is on assessing the role of flow unsteadiness induced by the pulsating flow environment that the twin-scroll turbine is subjected to. This is then to be followed by determining the attributes of turbocharger twin scroll turbine stage that would substantially improve efficient extraction of flow energy by the turbine. Thus another objective is to identify the efficiency limiting flow processes when the turbine is subjected to the pulsating flow environment representative of turbocharger twin scroll turbine operation. Accomplishment of this objective would provide a physical basis to formulate means, passive as well as active, to achieve a step improvement in the operating efficiency of the turbine stage. While the focus here is on turbocharger-engine, the outcomes and ideas conceived might be of utility to assessing turbine operations in pulsating flow environment induced by pulse detonation combustors.