Implementation of a New Predictive 0D/1D/3D Process for the Heat Release Prediction of a Gasoline Engine in the Early Development Stage.
To be published on April 2, 2019 by SAE International in United States
The automotive market need for shorter development cycles, as well as wider environmental concerns (climate change and poor air quality in cities), have promoted a revolution in digital engineering. Virtual hardware screening and engine calibration, before hardware is available, is a highly time and cost-effective way of reducing testing and shorting the time to bring product to market. Model-based development workflows, to be predictive, need to offer realistic combustion rate responses to different engine characteristics. The current approach, however, relies on empirically or experienced derived combustion responses, making the exploration of unconventional solution challenging. An alternative method that is less data and user experience dependent, is therefore needed. In this work a pragmatic engine development process based on a 0D combustion Stochastic Reactor Model (SRM) and in-cylinder cold CFD simulations is presented. Changes in Turbulent Kinetic Energy (TKE) and its dissipation (ϵ) in response to load and Start of Injection (SOI) have been investigated to develop a physical based map for turbulent mixing time (τ). The correlation reduced the number of cold CFD runs necessary making the 0D/3D approach run times acceptable for development applications. It was shown that a single baseline cold CFD run was enough to obtain a good correlation for the engine Rate of Heat Release (RoHR) and the knock tendency at the explored conditions. Further, a comparison of two injectors characterized by different sprays patterns has shown that the developed correlation correctly predicts the RoHR for two different tumbling motions in the condition explored. The presented augmented predictive capabilities, moved the engine development towards a less hardware dependent virtual approach, offering a practical solution for the exploration of new engine concepts.