Virtual Comprehensive Thermal Modeling to Improve Vehicle Component Durability and Environmental Sustainability

Purpose and goal

The goal is to significantly reduce time and cost for the development of new cars. To achieve this physical testing must be replaced with virtual analyses. The project´s goal was to develop a method with sufficient accuracy to predicting temperatures of the air and components in the engine compartment and along the exhaust system. The project has led to valuable knowledge and insight into transient thermal calculations. The methods maturity does not allow for replacement, but is currently used as a complement to testing, mainly in early stages, as supply of physical test data is poor.

Results and expected effects

The study covers calculated transient temperatures of 50 components and 200 measuring points. Acceptable deviation compared to physical tests is set to ± 10 C. Good conformity in level and trend (dT / dt) was achieved for about 50% of the analysed components. Approximately 30% exhibit either good maximum temperature OR trend, and 20% erroneous maximum temperature AND trend. Further development of the method is a necessity to achieve the long term goals. Efforts to eliminate the shortcomings and refine the method will continue in the context of ´Operational Development´ at Volvo Cars.

Approach and implementation

To manage the different time scales that physics require a pseudo-transient method is developed. Flow field is calculated stationary at selected occasions while thermal solution is calculated transient. A script developed in the project controls the coupling between the two. Improvements focused on modelling, i.e. the difference between an exact solution of the model equations and an analytical solution, and on systematic errors such as accuracy in the NGD and approximations of geometry, of boundary conditions and of transient physical processes in the calculation of flow field.