Application of a Diverging-Converging Duct to a FSAE Radiator System

Abstract

The focus of this paper is the design process for the radiator ducting on the WashU Formula Society of Automotive Engineers racing team vehicle. The side-pods for the WUFR-19 vehicle are designed as a diverging-converging duct around the radiator in order to provide a sufficient mass flow rate through the heat exchanger to cool the engine, while minimizing drag on the vehicle. Internal computational fluid dynamics simulations are run in ANSYS Fluent on an individual channel of the radiator core. A parametric setup is used to iterate through multiple inlet conditions. The goal of these simulations is to determine the relationship between the ducting inlet size, ram pressure and mass flow rate through the radiator core, while also accounting for heat transfer from the radiator in airflow conditions. The usage of internal simulations with varying inlet conditions reduces simulation time when compared to external side-pod simulations that have higher computational requirements and would require geometry modification between simulations. Results show that reducing the inlet size increases the pressure drop across and mass flow rate through the radiator for inlet sizes above 80% of the cross-sectional area of the radiator. Smaller inlet sizes begin to restrict airflow causing the mass flow rate to decrease. An inlet size of 70% of the cross-sectional area of the radiator and an outlet size of 80% of the inlet size were implemented in order to fully cool the engine and minimize drag on the vehicle.