A Numerical Investigation on a New Pulse-Optimized Flow Control Method for Turbocharger Turbine Performance Improvement Under Pulsating Conditions Available to Purchase

A turbocharger turbine in an internal combustion engine is fed with continuously pulsating flow due to nature of the exhaust flow of a reciprocating engine. It is generally acknowledged that the performance of the turbine deteriorates due to this pulsation. In order to address the problem, a novel pulse-optimized flow control method is introduced in this paper, which involves a specially-designed nozzle ring upstream of the radial or mixed flow turbine. Unlike a traditional turbocharger, in which the nozzle ring is stationary, the nozzle ring is rotating. The inception of this new flow control method is based on the fact that the variable magnitude of the unsteady exhaust flow can be converted into the variation of the flow angle by means of the rotating nozzle ring. The new method is then validated by a steady-state, single passage numerical model. Calculations with different nozzle rotating speeds under both high and low mass flow rate conditions were executed and the results demonstrated significant improvements in both stage efficiency and power output. The results predicted that the new pulse-optimized flow control method was able to enhance the turbocharger performance to a great extent by means of addressing the potential energy within the highly dynamic exhaust flows.