Assessment of a 1-D diesel engine model for accurate response in transient simulations

The complexity of modern powertrains with their embedded control systems has increased in the last years, due to the tightening of emission regulations. Therefore, virtual calibration and Model-in-the-Loop testing can provide a great support for their preliminary assessment, in order to reduce the experimental effort. To this purpose, highly accurate engine models are required, not only at steady-state conditions, but also in transient operation. The present paper addresses the assessment and validation of a fast-running 1-D model of a diesel engine for heavy-duty applications, focussing on the transient response. In particular, a baseline model with satisfactory accuracy at steady-state operation, but not in transient conditions, is analysed and assessed with the aim of reproducing the true dynamic response of the real engine installed at the test bench, as well as the behaviour of the embedded air-path controllers. The entire methodology for the model assessment is presented step by step, and common challenges and potential pitfalls that researchers may encounter when calibrating simulation models are discussed. Finally, the impact of the test bench layout on the engine dynamic response is also evaluated and discussed.