Search Results

Upper frame deflection of automobile doors is a key design attribute that influences structural integrity and door seal performance as related to NVH. This is a critical customer quality perception attribute and is a key enabler to ensure wind noise performance is acceptable. This paper provides an overview of two simulation methodologies to predict door upper frame deflection. A simplified simulation approach using point loads is presented along with its limitations and is compared to a new method that uses CFD tools to estimate aerodynamic loads on body panels at various vehicle speeds and wind directions. The approach consisted of performing external aerodynamic CFD simulation and using the aerodynamic loads as inputs to a CAE simulation. The details of the methodology are presented along with results and correlation to experimental data from the wind tunnel.

A detailed Design of Experiments (DOE) study is presented to understand the aerodynamic effects of exterior design features and shape parameters of a pick-up truck using Computational Fluid Dynamics (CFD). The goal of the study is to characterize several key design parameters and the interactions between them as related to overall drag of the vehicle. Using this data, the exterior shape is optimized to minimize drag within specified design constraints. An adaptive sampling methodology is also presented that progressively reduces errors in the design response surfaces generated. This combined with a Latin Hypercube based initial design space characterization yields computational efficiency. A trend-predictive meta-model is presented that can be used for early design development. Results from the meta-model are also correlated with experimental data from the wind tunnel.

Active grille shutter (AGS) in a vehicle provides aerodynamic benefit at high vehicle speed by closing the front-end grille opening. At the same time this causes lesser air flow through the cooling module which includes the condenser. This results in higher refrigerant pressure at the compressor outlet. Higher head pressure causes the compressor to work more, thereby possibly negating the aerodynamic benefits towards vehicle power consumption. This paper uses a numerical method to quantify the compressor power consumed in different scenarios and assesses the impact of AGS closure on total vehicle energy consumption. The goal is to analyze the trade-off between the aerodynamic performance and the compressor power consumption at high vehicle speeds and mid-ambient conditions. These so called real world conditions represent highway driving at mid-ambient temperatures where the air-conditioning (AC) load is not heavy.