Deployment of CFD for Optimization of the Air Flow Distribution Over the Windscreen and Prediction of Defrost Performance

In recent times, CFD (Computational Fluid Dynamics) simulation tools have been deployed by automotive OEMs for investigating Climate Control applications. In automotive vehicles, one such critical application is designing defroster nozzles with least flow resistance to carry hot air from HVAC (Heating Ventilation and Air Conditioning) unit and dispersing it onto the windscreen and side glasses to clear mist and ice. Clearance of windscreen and side window glass has a high importance for safe driving as mist and ice formation affects driver's visibility and comfort while driving in humid and snowy conditions respectively. In the present study, a half cabin model of the vehicle is prepared using commercial software package ICEM CFD as grid generation tool and CFD analysis is carried out using commercial software package FLUENT 6.3 to optimize the air flow distribution over the windscreen and then to predict defrost performance prior to full scale climatic wind tunnel tests. Reasonable correlation is observed between CFD predictions and the available test data. Using CFD as a means to evaluate performance in early development stage helps in reduction of vehicle development time, saves associated cost of prototype parts and physical testing efforts. CFD provides a better visualization of air flows in and around the vehicle and enhances understanding of the physical tests.