A Study of the Transient Analysis Technique on the Under Hood Thermal Damage

Vehicle engine cooling and under-floor heat protection is very important at the early stage of vehicle development. Nowadays, numerical analysis in this area is very common. Engineers can decide the radiator and bumper opening area, fan and radiator size by engine room airflow and temperature distribution analysis. At the same time, the results also can be used to prove effective heat protection method for the vulnerable components around the exhaust manifold and pipe. But, solving both cases at the same time is considered as very difficult because of large analysis domain, complicate model and very long solving time. The study provides an effective method for analysis the engine cooling and heat damage by two-way coupling between CFD code Star-CCM+ and a special heat transfer program RadTherm. Especially, the study attempted transient analysis at the ignition off condition just after 8%, 50kph uphill driving. At ignition off condition some components are over the limited temperature because of sudden disappearance of convection airflow. The results were compared with that of the climate wind tunnel test. It was found that the analysis technique could estimate the engine cooling performance very well and temperature distribution on the under-floor appropriately at the same time. Finally, temperature change over time of the under-floor components was estimated successfully.