Investigation of the control system for air supply during transient operation of a turbocharged diesel engine

Abstract

In the context of increasingly stringent emission standards and higher fuel efficiency requirements for turbocharged diesel engines, optimizing air-path control, particularly during transient operating conditions, has become essential. This study focuses on the design and evaluation of a dedicated air supply controller for transient operation to enhance the response and stability of a turbocharged diesel engine. The controller was developed to regulate the intake airflow dynamically through an auxiliary bypass line, compensating for turbocharger lag and maintaining stable boost pressure during rapid load or speed changes. Experimental results demonstrate that the proposed air supply controller significantly improves transient performance. Specifically, the transition time was reduced from 3 seconds to 1.5¸2 seconds, corresponding to an improvement of 16.6¸40%, while speed fluctuation Δn decreased by 8.5¸24%, depending on the load level. The best improvement was achieved at medium to high loads (50¸65%), indicating rapid and stable turbocharger response with the assistance of the supplemental air supply system. At low loads, the controller’s impact was less pronounced due to lower boost pressure and airflow rates. The results confirm that the proposed air-path controller for transient operation is a feasible and effective solution to shorten transient response time, reduce speed fluctuation, improve engine stability, and potentially reduce emissions in turbocharged diesel engines operating under rapidly varying conditions.