Atomization characteristics and prediction accuracies of hybrid break-up models for a gasoline direct injection spray

The purpose of this study is to investigate the prediction accuracy of hybrid models on the atomization processes of fuel sprays injected from a gasoline direct injection system. In order to analyze the prediction characteristics of hybrid schemes, various hybrid models for the primary and secondary break-ups of high-pressure gasoline spray are formulated by combining two different models. For the primary break-up, the LISA and WAVE break-Lip models are used, whereas the TAB, DDB, and RT models are utilized for the secondary break-up, considering the break-up mechanism of each break-up model. Therefore, six hybrid models are applied to the simulation of the atomization process and the prediction accuracies of the break-up processes are evaluated by comparing them with the experimental results. To obtain experimental results for comparison with the predicted ones, the local Sauter mean diameter and axial mean velocity are measured by using a phase Doppler particle analyzer. Also, the spray visualization system is utilized to analyze the process of spray development and spray-tip penetration. It is revealed that all hybrid models show reasonable agreement with the experimental results of spray-tip penetration. On the other hand, different accuracies are shown in the distributions of local SMD and axial mean velocity.