A fluid-structure- interaction based methodology to evaluate aero-thermal performance of deformable air guides

An air guide in a car directs fresh air onto the Heat Exchangers (HXs) to facilitate efficient thermal management. It is of paramount importance that the air guide creates a proper sealing and prevents any leakage of the incoming fresh air. It is achieved in two ways – 1) In the design condition, the air guide is manufactured in a way so that it overlaps/intersects with the surrounding components 2) the air-guide is made flexible with a highly elastic rubber seal at the edge. When the air-guide is assembled, the rubber portion of the air-guide deforms to produce a proper fit leading to a sealed air-intake pathway. At high-speed condition as well as high airflow conditions by the radiator fan during idling/stationary, like DC charging – incase of BEV, etc., the air guide encounters high pressure. Being elastic and flexible, these conditions make the air guide susceptible to deformation with potential leakage of incoming air. Digital evaluation of the air guide deformation at different high-pressure conditions early in the development phase can lead to significant cost and time saving. The present work demonstrates a Fluid-Structure Interaction based methodology that couples a Finite Volume and Finite Element based tools to estimate air guide deformation. The method starts with a digital assembly step where the assembly shape and the induced stress due to assembly is predicted. A full vehicle Aerodynamic simulation is performed to extract the surface pressure on the air guide which is then used to estimate the extent of deformation of the air guides. Based on the extent a subsequent Aerodynamic simulation may be carried out to predict thermal efficiency. Comparison against pressure data and deflection data extracted from the wind tunnel experiments of vehicles has shown reasonable match demonstrating the accuracy and usefulness of the method.