Experimental testing of an active control turbocharger turbine inlet equipped with a sliding sleeve nozzle

Abstract

The current paper presents the performance results of a variable-flow turbocharger turbine, called the active control turbocharger. Driven by the need to comply with increasingly strict emissions regulations as well as to strive continually for a better overall performance, the active control turbocharger is intended to provide an improvement over the current state-of-the-art turbochargers, namely the variable-geometry turbocharger. In this system, the nozzle is able to alter the throat inlet area of the turbine according to the variation in the energy (the pressure, temperature and mass flow) of each engine exhaust gas pulse with the intention of capitalising upon the untapped high-energy content of these pulses. The paper concentrates on the potential gain in the turbine expansion ratio and the eventual power output, as well as the corresponding effects on the efficiency as a result of operating the turbocharger in its active control mode compared with its operation as a standard variable-geometry turbocharger. This has meant actuation of the nozzle according to the pulse frequency, for different amplitudes and phase settings. The pulsating flow turbine power recovered increased by more than 15% compared with that from an equivalent variable-geometry turbocharger turbine, with the best phase offset between the minimum nozzle position and the start of the pulse (among the four tested) being 60°.