Utilization of a Twin Scroll Radial Centripetal Turbine Model

The article describes the utilization of the map-less approach in simulation of single and twin scroll radial turbines. The conventional steady flow maps are not used. An unsteady 1-D model of a twin scroll turbine includes scrolls, mixing of flows upstream of the impeller, turbine wheel, leakages and outlet pipe. Developed physical turbine model was calibrated with data from experiments at specific steady flow turbocharger test bed with open loop, which enables to achieve arbitrary level of an impeller admission via throttling in separate sections. A selected twin scroll turbine was tested under full, partial flow admission of an impeller and extreme partial admission with closed section. The required number of operating points is relatively low compared with conventional steady flow maps, when the maps have to be generated for each level of an impeller admission. The calibration process of the full 1-D turbine model is described. The fully calibrated 1-D twin scroll turbine model, in conjunction with an internal combustion engine model, is able to describe processes inside a turbocharger turbine under highly pulsating flow. The experiments were also performed on a turbocharged six cylinder diesel engine with twin scroll turbine. The engine was tested at steady and transient loads, and various speeds operation. The model of the internal combustion engine with the full 1-D model of the twin scroll turbine was properly calibrated by experimental data. The 3-D CFD model of the tested turbine is also introduced. The results of unsteady flow simulation, based on the in-house 3-D CFD finite volume solver, are compared with the 1-D simulation and also experiments. The results of steady and unsteady operation of the turbine and future utilization of developed simulation tools are discussed.