Potential Analysis of Exhaust Gas Turbochargers with Ejector Bypass

The article delves into the potential of exhaust gas turbochargers equipped with an ejector-based bypass, a technology that could offer a robust and cost-effective alternative to variable turbine geometry. Through a collaborative research project, the authors conducted extensive 3-D simulations and experimental investigations to analyze the internal flow processes of the ejector and determine key design parameters. The study revealed that the nozzle cross-section and bypass rate significantly influence pressure reduction downstream of the turbine, with the ejector effect enhancing momentum exchange and improving combustion engine efficiency. A predictive model was developed to facilitate geometric optimization and transferability across various vehicle applications. The findings indicate that the ejector bypass technology can reduce gas exchange work and residual gas content, particularly in passenger car gasoline engines, although implementation challenges related to thermal management and exhaust gas aftertreatment were also identified. The article concludes with a discussion on future research directions, including the development of an actuator for a variable primary nozzle and a comprehensive comparison with variable turbine geometry turbocharging systems.