Title: Effects of vehicle HVAC cowl box geometry on rainwater ingress

Authors: S.A.A. Abdul Ghani, A. Aroussi, E. Rice

Addresses: Flow Diagnostics Laboratory, University of Nottingham, University Park, Nottingham NG7 2RD, UK. ' Flow Diagnostics Laboratory, University of Nottingham, University Park, Nottingham NG7 2RD, UK. ' Visteon Corporation, Binley, Coventry, CV3 2UB, UK

Abstract: The penetration of rainwater through the heating ventilation and air conditioning system (HVAC) of a vehicle directly affects the provision of thermal comfort within the vehicle passenger compartment. Present vehicle designs restrict considerably the air-management processes due to reduced space and tighter packaging. In this study, a cowl box, the first element of the vehicle HVAC system, is examined through the scrutiny of the flow field prevailing within it. Particular attention is paid to the effects of reducing the cowl cross-sectional area on water ingress. The work described is both experimental and computational. An optical anemometer is used to acquire the experimental data within a transparent model of a cowl box. The results are then used to validate and tune the Computational Fluid Dynamics (CFD) calculations performed on the same cowl geometry as well as perform parametric studies of the features that affect the rainwater penetration. The phenomenon of rainwater ingress has integrated factors with the overall vehicle geometry and body seals at the cowl space, wipers set-up, HVAC blower setup, rain intensity and road conditions. Therefore, in addition to the model scale experiments, a full-scale vehicle is examined in the Flow Diagnostics Laboratory (FDL) Climatic Wind Tunnel. The results obtained, using nonintrusive instrumentation, are also used to verify the computational model.

Keywords: computational fluid dynamics; CFD; calculations; heating ventilation and air conditioning system; vehicle HVAC; rainwater penetration; thermal comfort; passenger comfort; vehicle design; air management; cowl box.

DOI: 10.1504/IJVD.2001.005223

International Journal of Vehicle Design, 2001 Vol.26 No.5, pp.541 - 561

Published online: 12 Sep 2004 *

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