ABSTRACT
The sequentially connected configuration of two stage turbine in a regulated two-stage turbocharger introduces a coupling effect of flow field between the high-pressure turbine (HPT) and low-pressure turbine (LPT), thus the performance of these two turbines will inevitably be affected by each other. However, most of current design methods of turbines assume they as isolated devices. In this study, a new method which is based on the control of flow-interaction between two stages is developed via experimentally validated three-dimensional numerical method. The influence of different positions of the bypass branch on the inter-stage coupling effects is investigated. Results manifest that different positions of the bypass branch significantly change the performance of low-pressure turbine and the flow interactions within the inter-stage. The detailed flow field analysis of the inter-stage pipe, volute and rotor is conducted to reveal the flow mechanism behind the inter-stage interactions.
