Fuel Rate Curve-Based Reverse Engineering Approach for Common Rail Diesel Injectors

When focusing on optimization of the combustion process in a direct injection engine, it is essential to understand its dynamic performance with respect to engine loading settings. One of the most important factors influencing the energy conversions efficiency is fuel delivery characteristics. The understanding of the injector performance is usually associated with availability of a high-fidelity model based on the geometric and hydraulic features of the injector. In this paper, a so-called reverse engineering method was applied to characterize the internal arrangement of a solenoid-driven common rail injector using fuel rate curves and solenoid valve excitation current profiles. Operational modes corresponding to a highly transient injector state were considered during spray momentum flux experiments to examine the injector flow characteristics. The experimental results were eventually used as a reference for the parameter search algorithm to tune a hypothetical model of the studied injector. In this work, the multi-start trust region optimization method was chosen as a relatively computationally cheap algorithm that allows realistic constrained parametrization of injector components. Based on the obtained results, it could be concluded that the reverse engineering approach is justified to heuristically model a common rail injector without the need for its dismantling. Furthermore, the developed model could be used as guidance for further improvement of injector design with respect to optimization of the combustion process inside internal combustion engines.