Improvement in Transient Performance of a Turbocharged Diesel Engine by Air Injection into the Compressor

One of the methods for improving the transient response of a turbocharged diesel engine is to accelerate the turbocharger by injecting air onto the impeller of the compressor. This paper describes experiments carried out on a turbocharger test rig in which air was injected through nozzles at the rotor tip of the centrifugal compressor; performance characteristics are presented. Results from these tests were then used to modify a digital simulation model of a medium-speed turbocharged diesel engine so that air injection could be applied at the onset of a load. Calculations show the predicted improvement in response of the system to step-load changes.