Set-up and Validation of an Integrated Engine Thermal Model in GT-SUITE for Heat Rejection Prediction
To be published on September 9, 2019 by SAE International in United States
Current approaches for heat rejection prediction during the development stage of a new engine are mostly based on maps built upon experimental data. However, these maps can be obtained fairly late in the development process, when at least a prototype of the engine can be run on the test bench. Furthermore, such experimental maps are limited to a discrete number of measured points, and they are not sensitive to variations in the engine calibration, vehicle installation and actual operating conditions. An innovative approach based on 1D simulation was tested in GT-SUITE, in order to shift in advance in the development cycle the moment at which reliable heat rejection calculations can be effectively used to support the engine and cooling system design. A fully physical Diesel engine performance model – featuring a predictive combustion model – was integrated with a detailed thermal model based on the 3D meshing feature available in GT-SUITE. Coolant and oil hydraulic circuits were implemented in the model and used to predict flow rate through the water jacket and oil gallery, respectively. In addition, a predictive detailed friction model of the cranktrain was built to better capture the interactions between metal and oil from the thermal standpoint. The integrated model was eventually validated against experimental measures and it proved to be an effective means to predict heat rejection when test data are not available yet. The predictive capabilities characterizing this model would also allow to test with a high level of reliability the impact on heat rejection and engine heat distribution given by a different engine calibration, components and operating conditions, with a noticeable saving of time and money compared to a traditional, fully-experimental-based engine development process.